Chapter 7: The OVERLORD Logistical Plan
The Artificial Port
The magnitude of the cross-Channel operation is most fully revealed in its logistic aspects. Because it was to be an amphibious operation OVERLORD’s supply problems were many times magnified. Moving an attacking force and its equipment across the Channel in assault formation required, first of all, a highly coordinated staging procedure in the United Kingdom, large numbers of special craft, and meticulously detailed loading plans. Following the capture of a lodgment it involved the rapid organization of the beaches as a temporary supply base, the quick reinforcement of the forces ashore and the build-up of supplies, and the subsequent rebuilding of ports and development of lines of communications so that sustained operations of the combat forces could be properly maintained.
The detailed planning for the various tasks involved did not begin until after the establishment of SHAEF and the designation of the Supreme Commander in January 1944. In the following month the plans of the various headquarters began to appear. The basic operational plan, known as the NEPTUNE Initial Joint Plan, was issued by the joint commanders—that is, the commanders of the 21 Army Group, the Allied Naval Expeditionary Force, and the Allied Expeditionary Air Force on 1 February. First Army’s plan, which constituted something of a master plan for U.S. forces in view of that organization’s responsibility for all aspects of the operation, both tactical and logistical, in its early stages, appeared on 25 February. Those of its subordinate commands, V and VII Corps, were issued on 26 and 27 March respectively. On the logistical side the joint commanders’ Initial Joint Plan was supplemented on 23 March by instructions known as the Joint Outline Maintenance Project. The outline of the American logistic plan was issued as the Joint Administrative Plan by the U.S. administrative staff at 21 Army Group on 19 April. This was followed on 30 April by the Advance Section plan, covering the period from D plus 15 to 41, and on 14 May by the over-all Communications Zone plan issued by the Forward Echelon. The SOS mounting plan had appeared on 20 March.
The extent to which logistic considerations had entered into the deliberations of the COSSAC and SHAEF planners has already been pointed out. In the eyes of the planners the successful invasion of France was dependent first on breaking through the coastal defenses and establishing a beachhead, and second, on the subsequent battle with enemy mobile reserves. The enemy’s main line of resistance was the coast line itself, and it was known that the first objective of the enemy’s defense strategy was to defeat the
invaders on the beaches by the rapid deployment of his mobile reserves. The outcome of this critical battle with enemy reserves was seen as depending primarily on whether the Allied rate of build-up could match the enemy’s rate of reinforcement, and the degree to which this reinforcement could be delayed or broken up by air action or other means. The enemy’s second defense objective would be to prevent the Allies from securing ports, for the capture of an intermediate port, such as Cherbourg, and of other ports, was a prime necessity for the sustained build-up of men and supplies.1
In the original July 1943 outline plan of OVERLORD, which served as a basis for the later planning, it was estimated that the provision of adequate maintenance for the Allied forces in the initial stages, including the building of minimum reserves, would require a flow of supplies rising from 10,000 tons per day on D plus 3 to 15,000 tons on D plus 12, and 18,000 on D plus 18. These figures were based on an assault by three divisions, a build-up to a strength of ten divisions by D plus 5, and the landing of approximately one division per day thereafter.2 The capture of the Normandy and Brittany groups of ports was expected to insure discharge capacity sufficient to support a minimum of at least thirty divisions, and it was believed that if all the minor ports were developed this force could be considerably augmented. But frontal assaults on the ports themselves had been ruled out, and Mediterranean experience had shown that ports, even if captured shortly after the landings, would be found demolished and would be unusable for some time. The total capacity of the minor ports (Grandcamp-les-Bains, Isigny, St. Vaast-la-Hougue, Barfleur) on the front of the assault was not expected to reach 1,300 tons per day in the first two weeks. According to a later estimate, the capture of Cherbourg was not expected before D plus 14. Its capacity on opening was estimated at 1,900 tons, rising to only 3,750 tons after 30 days. In any event it was not sufficient for the maintenance of the lodgment forces. The Brittany ports would not offer a solution before D plus 60. It was clear, therefore, that the initial build-up would have to be over the beaches, and it was estimated that eighteen divisions would have to be supported over the beaches during the first month, twelve in the second, with the number gradually diminishing to none at the end of the third month as the ports developed greater and greater capacity.
The COSSAC planners considered the capacities of the beaches (which at that time did not include the east Cotentin) more than sufficient to maintain these forces, and believed that tactical developments should make possible the opening of additional beaches after D plus 12.3 Unfortunately these capacities were largely theoretical, and in this fact lay the very crux of the initial build-up problem. The Allies had two enemies to reckon with in their invasion of the Continent—the
Germans and the weather. By far the more unpredictable of these—”more capricious than a woman,” as one observer put it—was the weather.4 Meteorological studies covering a ten-year period indicated that the month of June was likely to have about twenty-five days of weather suitable for the beaching of landing craft. The record also revealed an average of about two “quiet spells” of four days or longer per month between May and September. Forecasting more than four days of fair weather was difficult, however, and it therefore followed that from D plus 4 onward maintenance plans would have to allow for the fact that on some days beach operations would be impracticable. To compensate for these interruptions it would be necessary to increase daily discharge by some 30 percent. Furthermore, even though it might be physically possible to land the necessary tonnages, a great problem of movement and distribution forward to the depots and the troops was inherent in maintenance on such a large scale in so restricted a beachhead. It was therefore necessary to develop discharge facilities for bad weather in order to reduce the peak loads over the beaches on operable days and to even out the flow of traffic through the maintenance areas. In addition, naval authorities warned that unless steps were taken to provide facilities for the landing of vehicles, the cumulative damage to craft continuously grounding on beaches might well reduce the available lift and jeopardize the success of the whole operation. The provision of special berthing facilities was considered a matter of such paramount importance, in fact, that the naval commander in chief stated he could not undertake such an operation with confidence without them.5
The planners made it clear at an early date, therefore, that unless adequate measures were taken to provide sheltered waters by artificial means the operation would be at the mercy of the weather, and that a secondary requirement existed for special berthing facilities within the sheltered area, particularly for the discharge of vehicles. They estimated that the minimum facilities required for discharge uninterrupted by weather were for a capacity of 6,000 tons per day by D plus 4–5, 9,000 tons by D plus 10–12, and 12,000 tons when fully developed on D plus 16–18.
The Allied planners proposed to meet this problem by building their own harbors in the United Kingdom, towing them across the Channel, and beginning to set them up at the open beaches on the very day of the assault. While their solution was in a sense an obvious one, it was at the same time as unconventional and daring in its conception as any in the annals of military operations.
The concept of a “synthetic” harbor was not entirely a new one, although a detailed blueprint for a prefabricated port was not immediately forthcoming. There was at least one precedent for the concept of “sheltered water” created for the express purpose of aiding military operations. Mr. Churchill had proposed a breakwater made up of concrete caissons in 1917 in connection with proposed landings in Flanders.6 In World War II Commodore John Hughes-Hallett, senior naval representative of the C-in-C Portsmouth, was the real progenitor of the artificial
harbor, although the Prime Minister again provided much of the inspiration and the drive in working out the solution of this basic invasion problem. In May 1942 Mr. Churchill sent his oft-quoted note to the Chief of Combined Operations directing that a solution be found for the problem of special berthing facilities on the far shore. Suggesting piers which “must float up and down with the tide,” he ordered: “Don’t argue the matter. The difficulties will argue for themselves.”7
Under the direction of COSSAC British engineers carried out experiments in the spring of 1943 to determine the practicability of constructing a prefabricated port, and they succeeded in building a floating pier that survived the test of a Scottish gale. But the exact form which such a port should take was not immediately determined, and the digest of OVERLORD presented by General Morgan to the Combined Chiefs of Staff at Quebec in August 1943 consequently included only the most tentative outline plan for such a harbor. The sheltered anchorage, this plan “suggested,” would be formed simply by sinking nineteen blockships to form a breakwater. Berthing facilities would be provided by four pierheads, consisting of four sunken vessels, which were to be connected to the shore by “some form of pontoon equipment.” The daily discharge capacity of such an installation was expected to be approximately 6,000 tons.8 The relatively simple form of the harbor thus outlined hardly suggested the myriad engineering problems that still had to be overcome, and resembled only in its barest essentials the harbors which eventually took form.
The difficulties did indeed argue for themselves as Mr. Churchill predicted, for the magnitude and complexity of the task became more and more apparent. Many of the world’s ports were “artificial” in that their sheltered harbors had been created by the construction of breakwaters. Cherbourg and Dover were both “made” ports in this sense. But whereas it had taken seven years to build the port of Dover in peacetime, the Allies were now faced with the problem of building a port of at least equal capacity in a matter of a few months, towing it across the Channel, and erecting it on the far shore amidst the vicissitudes of weather and battle. The plans as they were eventually worked out in fact called for the erection of two ports within fourteen days of the landings.
Two major requirements had to be met: a breakwater had to be provided to form sheltered anchorage and thus permit discharge operations in bad weather; piers were needed onto which craft could unload and thus supplement discharge from beached craft. Several solutions were considered in connection with the problem of providing sheltered water. In 1942 Commodore Hughes-Hallett proposed the use of sunken ships to form a breakwater. To the Admiralty this suggestion at first represented nothing but the sheerest extravagance in view of the impossible task it already faced in replacing the shipping lost to enemy submarines. The use of floating ships had the same drawback, of course, and in addition presented a difficult mooring problem.9 One of the more novel solutions suggested was the creation of an “air breakwater.” By the use of pipes on the
ocean floor this scheme proposed to maintain a curtain of air bubbles which theoretically would interrupt the wave action and thus provide smooth waters inshore of the pipe.10 This idea was actually not new either. Studies along this line had been carried out in the United States forty years before, and both Russian and U.S. engineers had conducted model experiments since 1933, although without conclusive results. The bubble breakwater would have required such large power and compressor installations that it was impractical for breakwaters on the scale envisaged, and the idea was discarded as infeasible early in September 1943.11
Meanwhile experimentation was carried on with several other schemes. One of the earliest to receive attention was a device called the “lilo,” or “bombardon.” Li-lo was the trade name for an inflated rubber mattress used on the bathing beaches in England. A British Navy lieutenant had casually observed at a swimming pool one day that the Li-lo had the effect of breaking up wavelets formed on its windward side, creating calm water in its lee, and conceived the idea of constructing mammoth lilos for use as a floating breakwater. The idea was believed to have possibilities, and experimentation began in the summer of 1943. As first conceived the lilo—or BOMBARDON, the code name by which it was better known—had two basic components: a keel consisting of a hollow concrete tube 11 feet in diameter; and a canvas air bag above, about 12 feet in diameter and extending the entire length of the unit. The keel could be flooded and submerged while the air bag extended above water. The BOMBARDONS were 200 feet long and had a 12-foot beam and a 13-foot draft, the concrete keel alone weighing about 750 tons. The first designs called for a rubberized canvas air bag, and a few units of this type were constructed. Since they were vulnerable to puncture by small arms fire, however, later designs provided for a steel cruciform superstructure, about 25 feet in width.12
In essence the BOMBARDON breakwater would consist of a string of huge, air-filled, cylindrical floats, moored at each end, but laced together to form a thin screen of air which was intended to break up wave action and thus provide sheltered water. The BOMBARDONS were believed to have an advantage over sunken blockships since they could be moored in comparatively deep water and thus provide sheltered water for the deeper-draft Liberties.13 Nevertheless, from the very beginning there were doubts about their effectiveness and feasibility, and they were never expected to do more than dampen wave action and provide anchorage supplementary to the main harbor for deep-draft ships.
Meanwhile experimentation had gone forward on another solution to the problem—the caisson, or PHOENIX, which eventually was to constitute the main element in the breakwater forming the harbor. The PHOENIXES were huge, rectangular, concrete, cellular barges designed to perform much the same function as sunken blockships. Their main specification was that they have sufficient weight and strength to withstand summer Channel weather; at the same time they had to be towable, easily sinkable, and of simple enough design to be constructed with a
CAISSONS, used for MULBERRY breakwater, sunken in position off the beaches
CAISSON afloat
minimum expenditure of labor and materials. Five types were eventually built, varying between 175 and 200 feet in length and between 25 and 60 feet in height, the largest of them weighing 6,000 tons and drawing 20 feet of water. The PHOENIX consisted fundamentally of a reinforced base with side walls tied together by reinforced concrete bulkheads. Each was to be given a 10-foot sand filling to achieve the proper draft, then towed across the Channel, flooded, and sunk at the 5-fathom (30-foot) line. The great height of the PHOENIXES was dictated by the desire to provide a breakwater at sufficient depth to accommodate Liberty ships, which drew as much as 28 feet when loaded. The beaches selected for the assault had a very shallow gradient and tide ranges of more than 20 feet. The harbor therefore had to extend a full 4,000 feet from the shore in order to provide sheltered water for Liberty ships at low tide, and the largest caissons had to be 60 feet high in order to rest on the ocean floor and still provide a sufficient breakwater for deep-draft vessels at high tide.14
Experimentation on the second vital portion of the harbor—the berthing and unloading facilities within the breakwater—had begun somewhat earlier in response to the Prime Minister’s directive in 1942. This was fortunate, for the engineer problems involved proved far more complex than those met in the construction of the PHOENIXES. Once again the gradient of the beaches and tidal conditions largely determined the requirement. Low tide along the Normandy coast uncovered as much as a quarter of a mile of beach, and it was necessary to go out another half mile to reach water of sufficient depth—12 to 18 feet—for the discharge of coasters.
The equipment developed to bridge this gap consisted of two basic components: pierheads, at which vessels were to berth and unload; and piers or roadways which connected the pierheads with the shore. Both were designed mainly by the British and involved an ingenious piece of engineering. The Lobnitz pierhead, as it was called, was an awesome-looking steel structure 200 feet long, 60 feet wide, and 10 feet high, weighing upwards of 1,500 tons. At each corner of the structure was a 4 x 4-foot spud leg 90 feet high, the height of which could be adjusted independently by means of winches located between the decks. These spud legs could be retracted during the towing of the structure. Once the pierhead was placed in position the legs were lowered, their splay feet digging into the sea floor to steady the structure, and their height was then adjusted to keep the pierhead at uniform height above water at all stages of the tide. The Lobnitz pierheads were intended to provide the principal unloading facilities for LCTs and LSTs that were not beached and for coasters. They were so designed that any number could be linked together to form an extended berth. To connect pierheads with the shore a flexible steel roadway, known as the WHALE, was developed. The WHALE pier consisted essentially of 80-foot sections of steel bridging, linked together by telescopic spans which gave it the needed flexibility to accommodate itself to wave action, the entire WHALE structure resting on concrete and steel pontons known as “beetles.” At low tide the sections near the shore would come to rest on the sand.
In the summer of 1943 the design of the artificial harbor had hardly reached the finality suggested by the above descriptions
LOBNITZ Pierhead
of its various components. Because experimentation had not yet produced conclusive solutions to many problems, the plan which COSSAC submitted at Quebec in August was necessarily sketchy and vague. Nevertheless the Combined Administrative Committee of the Combined Chiefs of Staff concluded at that time that the construction of artificial harbors was definitely feasible, and approved the project in its general outline. Early in September it rejected the bubble breakwater idea, but recommended continued experimentation with all the other proposed solutions—BOMBARDONS, PHOENIXES, and sunken and floating ships—and urged the immediate construction of PHOENIXES and BOMBARDONS without awaiting the completion of trials and prototypes of the latter. These projects were given the highest priority for labor, equipment, shipping space, and supplies, and construction of the first units now began in earnest.
The respective spheres of responsibility of the United States and Britain with regard to experimentation and construction were also defined in September. By far the largest portion of the work had to be carried out in the United Kingdom, and the British consequently assumed major responsibility for the design, testing, and construction of the PHOENIXES, BOMBARDONS, pierheads, and WHALE bridging.
Trials with floating-ship breakwaters were to be carried out in the United States, and the United States was also called on to provide some of the tugs that would be required for towing purposes beginning just before D Day. The construction of BOMBARDONS and the provision of ships for the breakwater were Admiralty responsibilities; all other components were to be designed and built by the War Office.15
The principal units under construction or trial by late November were the BOMBARDONS, PHOENIXES, sunken- and floating-ship breakwaters, pierheads, and piers.16 There still was no definite blueprint of the harbors at that time, for there was continuing indecision as to the form the harbor should take. The use of sunken ships was still being considered, although it was realized that they were adaptable as a breakwater only in shallow water. The use of floating ships as a deep-water breakwater received less and less favorable consideration because of the mooring problem involved.17 The relative merits of BOMBARDONS and PHOENIXES were still being discussed, but there was continuing doubt as to the practicability of the former. Despite the indecision on these matters the final COSSAC draft of OVERLORD, published late in November 1943, specifically provided for two major artificial ports, one to be located at Arromanches-les-Bains in the British sector, with a capacity of 7,000 tons per day by D plus 16 or 18, and one at St. Laurent-sur-Mer in the American sector, with a capacity of 5,000 tons. For reasons of security the two projects had by this time ceased to be referred to as artificial ports. Late in October they had been christened with the code name by which they were henceforth known, the American port being designated MULBERRY A, and the British port as MULBERRY B.18
The design of the ports was more clearly established early in 1944. By January the concrete caisson or PHOENIX was definitely adopted as the principal unit of the breakwater. It was to be supplemented by sunken ships, the main reason being that sheltered waters were needed for a large number of craft in the earliest stages of the operation. Staff requirements had been amended in January to provide facilities for the discharge of 2,500 vehicles per day (1,250 at each port) by D plus 8 in addition to the tonnage already mentioned, and for shelter for small craft. The MULBERRIES were still big question marks at this time, as indeed they continued to be until the very time they began operating. In any case, naval authorities were very doubtful as to whether the harbors could be effective by D plus 4, when a break in the weather could be expected. They had therefore proposed the construction of five partial breakwaters, known as GOOSEBERRIES, each about 1,500 yards long, formed of blockships (referred to as CORNCOBS) sunk on the 2-fathom (12-foot) line at low water. There was to be one GOOSEBERRY at UTAH Beach, one at OMAHA, and one at each of the three British beaches. Seventy ships were to be used for this purpose, steaming across the Channel and going into position on D plus 1. Ballasted to draw 19 feet of water, they were to be prepared with explosive charges which would be fired after the
ships were properly planted, blowing holes below the water line so that they would sink rapidly.19 These shallow-water GOOSEBERRIES would provide early protection for the large number of tugs, ferries, DUKWs, and landing craft plying between the ships and beaches and for the craft which had been beached. At OMAHA and Arromanches they would tie in with the PHOENIXES to form a longer breakwater enclosing the entire harbor.20 The sheltered area formed by the breakwater at MULBERRY A was to provide a harbor of about two square miles, with moorings for 7 Liberty ships, 5 large coasters, and 7 medium coasters.
The plans for berthing and discharge facilities at the American installation finally called for three WHALE piers or roadways, one of 40 tons capacity (which could carry tanks) and two of 25 tons capacity. All three were to extend more than 3,000 feet out from the shore to about the two-fathom line. There they were to converge on six Lobnitz pierheads, grouped to accommodate both LSTs and coasters. These installations were to give the port a capacity of 5,000 tons of cargo and 1,400 vehicles per day. This was regarded as a conservative estimate, and the capacity of the harbor was actually believed to be well in excess of this minimum.21 In addition to these facilities, two ponton causeways were to be constructed at both OMAHA and UTAH Beaches to boost the unloading facilities for small craft such as LCTs and barges. These causeways were to be built of 5 x 7 x 5-foot ponton cells, bolted together into sections two cells wide and thirty long, and linked to form a roadway 14 feet wide and 2,450 feet long.22 (Map 7)
Both the British and American MULBERRIES eventually also included a row of BOMBARDONS, despite continued misgivings as to their probable effectiveness.23 These ungainly looking floats were to be placed about 5,000 feet seaward of the high-water mark to break the swell and form an additional deep-water anchorage for the discharge of Liberty ships. The UTAH Beach installation was to be much less elaborate. It was to have only a GOOSEBERRY breakwater, formed by sinking ten blockships beginning on D plus 1, and the two ponton causeways.
Over-all command of both MULBERRIES was given to Rear Adm. William Tennant (British). On the U.S. side Capt. A. Dayton Clark was placed in command of MULBERRY A, organized as Naval Task Force 127.1, but usually referred to as Force MULBERRY. Brigadier Sir Harold Wernher was designated to coordinate the work of the War Office and the civilian Ministries of Labour and Supply in the construction of the many components of the ports.
The construction and assembly of all the special port equipment proved a formidable task, and, along with the many other preinvasion preparations, taxed the resources of the United Kingdom to the
Map 7: Plan of MULBERRY A at OMAHA Beach
very limit in the last months before D Day. Many a sacrifice had to be made to permit the huge project to go forward, the Ministry of Labour giving up expert tradesmen and power equipment, the Army temporarily releasing men from the colors, the Navy foregoing frigate and aircraft carrier production. As General Morgan later observed, “Half of England seemed to be working on it and a lot of Ireland as well.”24 Despite the high priorities covering all phases of the project, planners and commanders responsible for the MULBERRIES were haunted by a thousand and one problems and fears until the ports were finally established, and they had to make many compromises with the goals originally set. Early in 1944, plans called for the construction of 113 BOMBARDONS, 149 PHOENIXES, 23 pierheads, and 6 roadways, and for the acquisition of 74 vessels for the sunken-ship breakwaters. The towing problem involved in the assembly and movement of the 600-odd major units involved was unprecedented. It was estimated at first that 200 tugs
would be needed for the task and that they would be occupied a full three months.
These requirements soon proved beyond the capabilities of U.K. resources. The construction of PHOENIXES had begun at the end of October 1943. Within two months the work had already fallen three or four weeks behind schedule, partly because the design of the caissons was altered, partly because the proper types of freight wagons to deliver steel were in short supply, and partly because contractors were unable to obtain the allocation of enough laborers, particularly in certain skilled categories. By 1 December 15,000 workers were supposed to have been assigned to the PHOENIXES, but less than half this number were on the job at that date.25 To meet the labor requirements it was eventually necessary to hire large numbers of Irish workers—a measure that involved additional security risks. Finding construction sites alone was a tremendous problem, for each caisson was equivalent in size to a five-story building. Some of the caissons were built at the East India docks in London, but dry docks were not available for the entire project, and special basins had to be dug behind river banks along the tidal stretches of the Thames, where the work was partially completed. The banks were then dredged away and the units floated to wet docks for completion. Construction of the PHOENIXES was farmed out to some twenty-five contractors and eventually required about 30,000 tons of steel and 340,000 cubic yards of concrete in addition to other materials.26
In the construction of the Lobnitz pierheads, which got under way somewhat earlier, bottlenecks developed also. In December 1943 it was announced that only 15 pierheads could be delivered by D Day instead of the desired 23. Plans for the U.S. MULBERRY, which had called for 8 of these units, were therefore altered to provide for only 6. Because of prior commitments for the manufacture of landing craft and heavy engineering equipment it was necessary, as with other components, to split up the contracts among a large number of structural steel works in all parts of the country and to prepare entirely new shipbuilding sites for the launching of the pierheads. The same was true in the construction of the WHALE bridging for the roadways, and because of the wide distribution of the contracts it was almost impossible to obtain details of the manufacturing progress. About 240 firms were eventually involved in fabricating the materials for these units, using 50,000 tons of steel.27 When construction fell behind schedule in March and April, a U.S. Naval Combat Battalion (the 108th) was assigned to assist in the manufacture of this equipment.28
Shortages of one type or another also forced a reduction in the number of BOMBARDONS and in the number of ships for the GOOSEBERRIES. The number of BOMBARDONS was eventually cut from 113 to 93. In the case of the blockships the original
request for about 80 had brought loud protests from the Admiralty. When the admirals began to ponder the probable alternative, however, and visualized their landing craft smashing against the beach for lack of sheltered waters, they reconsidered, and more than 70 vessels—”mostly old crocks”—were eventually provided, about 25 of them by the U.S. War Shipping Administration and the remainder by the Ministry of War Transport.29
The towing problem finally proved as onerous as any of the other procurement difficulties, and in the final months before the invasion it was touch and go as to whether the lag in construction or the shortage of tugs would be the greater limiting factor. Until the end of April construction was the main worry, and in that month the Ministry of Production even provided a labor reserve to meet any emergency demands.30 But anxiety over the construction schedule was eased somewhat in May, and all the essential units were in fact ready by the time of the invasion, although it was after the middle of May before the first operational Lobnitz pierhead was turned over to its U.S. Navy crew at Southampton. Fortunately the commander of the American Force MULBERRY ordered a thorough test of the pierhead that included discharging a fully loaded LST. The trial run disclosed numerous defects, and men struggled night and day under the relentless driving of the indefatigable Captain Clark to make the necessary modifications.31
No amount of last-minute effort could surmount the towing problem, and in the end it proved to be the most critical bottleneck. As each piece of equipment was completed it had to be towed, in some cases hundreds of miles, to the place of assembly on the south coast of England, and the movement of 600-odd units to the far shore within a two-week period posed the biggest tow job of all. The construction delays that developed in the spring only aggravated the problem, for the failure to complete units on schedule had the effect of compressing all towing commitments into a shorter period. There was little point in meeting construction schedules, in other words, if tugs were unavailable to tow units across the Channel. Here was another example of a single shortage or shortcoming creating a bottleneck which threatened to frustrate the successful execution of an entire plan. It was estimated in February that 200 tugs would be needed for all invasion commitments, of which 164 were required for the MULBERRY units. An allocation of 158 tugs was made for the artificial ports sometime during the spring; but despite the rounding up of every suitable vessel that could be spared in both the United Kingdom and the United States, only 125 were made available by the time of the invasion. Of these, 24 were taken for temporary service with various types of barges, leaving a bare hundred to meet the MULBERRY requirements. In light of this shortage it was necessary on the very eve of the invasion to set back the target date for the completion of the MULBERRY installations on the far shore from D plus 14 to D plus 21.32
In the months just before the invasion the question of how long the artificial ports were to be kept in operation received increasing attention. This matter was closely related to the estimates as to when the deep-water ports could be captured and brought into operation. The original plans for the artificial ports provided that they were to remain effective for ninety days, by which time deep-water ports were expected to be restored and able to handle the required tonnages. As early as March, however, after the tactical plan was revised, further logistical studies of the maintenance problem after D plus 90 revealed that the capacity of the ports would almost certainly have to be supplemented by that of the MULBERRIES for an additional thirty days (to D plus 120) and, unless operations went extraordinarily well after D plus 120, even through the winter months. Even if the Loire and Brittany ports were captured by D plus 45, it was concluded, the difficulties likely to be met in restoring and operating the lines of communications made it doubtful that U.S. forces could be supported entirely through those ports by D plus 90, and the British would not be able to have the sole use of Cherbourg after that date, as planned. In any case, Cherbourg and the smaller Cotentin ports did not have sufficient capacity in themselves to maintain the British forces after D plus 90. Thus, if the Seine ports were not captured and put into operation by D plus 120 it would be essential to keep the MULBERRIES operating to maintain British forces. The chief administrative officer at SHAEF, Lt. Gen. Sir Humfrey M. Gale, therefore urged that measures be taken to extend the usefulness of these ports. This entailed the construction of additional PHOENIXES as reserves and also the strengthening of the ports during the summer so that they might withstand the winter gales. General Gale also requested that spare blockships be provided to replace any that might break up. The necessity for prolonging the life of the MULBERRIES was immediately accepted, and in March construction of an additional 20 PHOENIXES was therefore approved.33
Beach Organization
While the artificial ports represented one of the most ingenious engineering accomplishments and one of the invasion’s most expensive investments of resources, they were to remain largely untried expedients and therefore unknown quantities until they were subjected to the twin tests of battle and weather off the Normandy coast. Of equal importance to the logistic preparations for the operation was the organization of the beachs, across which all equipment and supplies would have to pass in the initial stages regardless of whether they were discharged at the pierheads and brought ashore via the roadways or were discharged from landing craft at the water’s edge.
Beach organization was to have special importance in OVERLORD because of the magnitude of the forces to be built up over the Normandy beaches and because of the extended time during which the beaches were to serve as major points of entry for both troops and supplies. The OMAHA and UTAH Beach areas were to be the bases for
the first continental lines of communications. The initial organization of these areas was therefore a vital preliminary step in the transition to the normal administrative organization provided by the Communications Zone.
Responsibility for developing and operating the first supply installations on the far shore was assigned to the engineer special brigades: the 1st Engineer Special Brigade at UTAH, and the Provisional Engineer Special Brigade Group, consisting principally of the 5th and 6th Brigades and the 11th Port,34 at Omaha where the MULBERRY was to be located. As attachments to the First Army in the first stages of the operation these units were required to prepare plans based on the engineer special brigade annex to the First Army plan, and the brigades accordingly carried out detailed planning for the early organization of the beach areas.
In the next chapter more will be said about the origins and development of the engineer special brigades. These organizations, mothered by the necessities of the frequently recurring amphibious operations of World War II, were specially trained and equipped to handle the technical organization of the beaches. As outlined by a First Army operations memorandum, their general mission was “to regulate and facilitate the landing and movement of personnel and equipment on and over the beach to assembly areas and vehicle parks, to unload cargo ships, to move and receive supplies into beach dumps, to select, organize, and operate beach dumps, to establish and maintain communications, and to evacuate casualties and prisoners of war over the beach to ships and craft.”35 In short, it was their duty to insure the continuous movement of personnel, vehicles, and supplies across the beaches in support of a landing operation. By “the beaches” was normally meant an area known as the “beach maintenance area,” which included the beach, the first segregated supply dumps inland, and the connecting road net, an area which usually did not extend more than three miles inland. At OMAHA the beach maintenance area included MULBERRY A and the minor ports in the vicinity.
The mission defined above involved a formidable list of tasks. Among them were the following: marking hazards in the vicinity of the beaches and determining the most suitable landing points; making emergency boat repairs; establishing medical facilities to collect, clear, and evacuate casualties to ships; controlling boat traffic; directing the landing, retraction, and salvage of boats; maintaining communications with naval vessels; marking landing beach limits; constructing and maintaining beach roadways and exit routes; establishing and marking debarkation points and landing beaches; unloading supplies from ships and craft; assisting in the removal of underwater obstructions; clearing beaches of mines and obstacles; erecting enclosures for guarding prisoners of war, and later evacuating them to ships; establishing army communications within the brigade and with other brigades and units ashore; constructing landing aids; maintaining liaison with senior commanders ashore and afloat; maintaining order and directing traffic in the beach maintenance area; providing bivouac, troop assembly, vehicle parking, and storage areas in the beach maintenance
area for units crossing the beach; regulating and facilitating the movement of unit personnel and equipment across the beach and insuring the rapid movement of supplies into dumps; selecting, Organizing, and operating beach dumps for initial reception and issue of supplies; selecting, organizing, and operating beach maintenance area dumps until relieved by the army; maintaining records showing organizations, materials, and supplies which had been landed; providing for decontamination of gassed areas in the beach maintenance area; maintaining an information center for units landing; operating emergency motor maintenance service to assist vehicles and equipment damaged or stranded in landing and requiring de-waterproofing assistance; providing local security for the beach maintenance area; and coordinating offshore unloading activities.
Many of these tasks obviously called for troops other than engineers. In this respect the name “engineer special brigade” is misleading, for while the core of the brigade consisted of engineer combat battalions, each brigade normally contained a body of Transportation Corps troops, such as amphibian truck companies and port companies, exceeding the size of the engineer component, plus quartermaster service and railhead companies, and ordnance, medical, military police, chemical, and signal troops. In addition, depending on its mission, each brigade was augmented by the attachment of a host of other units and special detachments such as bomb disposal squads, naval beach units, maintenance and repair companies, fire-fighting platoons, and surgical teams, which might raise its total strength to 15,000 or 20,000 men. The engineer special brigade was a hybrid organization, therefore, without standard composition. But it was exactly this feature which gave it the desired flexibility and permitted it to be tailored to any task in an amphibious operation.
Portions of the brigades were scheduled to follow closely on the heels of the initial assault waves. Within the first two hours of the landings they were expected to complete the initial reconnaissance and beach marking preliminary to the development of the beaches. In that period advance parties of engineer shore companies, signal teams, and naval units were to come ashore, survey beach and offshore approaches, plan the layout of beaches for landing points, roadways, and exits, install ship-to-shore signal stations, and erect beach markers. Within the next two hours additional elements of the brigade would arrive, remove mines and beach obstacles, decontaminate beach areas, lay beach roadways, complete exits, establish collecting and clearing stations, start controlling traffic, build stockades for the control of prisoners of war, assist stranded craft, control boat traffic, reconnoiter initial dump areas, and establish motor parks for first aid to water-stalled vehicles. By the end of the first day the brigade was to have established the brigade command post, a signal system, and assembly areas for troops, sign-posted all routes to the dumps, repaired roadways to the dumps, opened beach exits, organized antiaircraft defense, organized initial dumps for the receipt, sorting, stacking, inventory, and issue of supplies, and to have started unloading supplies. Initial beach dumps were to be in full operation by the end of the first day. Within the next few days supplies were to be routed to new dumps established farther inland in the beach maintenance area.
Brigade units were so grouped for the assault that they could operate independently in support of specific landing forces. Each brigade was broken down into battalion beach groups, each consisting of an engineer combat battalion reinforced with the service elements necessary to support the assault landing of a regimental combat team. The battalion beach groups were further subdivided into companies, each of which was to support the landing of a battalion landing team and operate a beach of about 1,000 yards frontage. Once a beachhead had been won and the buildup began, service troops of the battalion beach groups were to revert to their parent units and operate under brigade control. At this stage the brigades would move out of the narrow confines of the beach itself and begin to develop the beach maintenance area.36
The beach maintenance areas in effect would be microcosms of the future Communications Zone, for the brigades performed there most of the functions which the expanded Communications Zone later carried out in its base and advance sections. Each brigade was organized to move 3,300 tons of supplies per day from ships and craft into segregated dumps, and to provide the technicians and labor necessary to operate those dumps. As tonnage requirements increased, the capacity of the brigades was to be increased by the attachment of additional service troops, the improvement of beach facilities, and the development of local ports. As the MULBERRY was completed and the minor ports were rehabilitated, other service troops were to be utilized under brigade attachment to operate them. This initial development of the continental supply structure was to be carried out directly under the control of the First Army, which planned to relieve the engineer special brigades of responsibility for operating the dumps in the beach maintenance area as early as possible, using its own service units for this purpose. Eventually, of course, an army rear boundary would be drawn, and the rear areas and the brigades themselves would be turned over to the Advance Section, which would assume full responsibility for operating the embryo Communications Zone until the arrival of the Forward Echelon of that organization itself.37
The brigades were thus destined to play an essential role in initiating the development of the far-shore logistic structure. Since they were to land in the first hours of the invasion, while the beaches were still under fire, they were expected to perform both combat and service missions. That they were aware of their dual role is indicated by their reference to themselves as “the troops which SOS considers combat, and the combat troops consider SOS.”
Port Reconstruction
While the organization of the beaches and the MULBERRIES was important for the initial supply and build-up of forces on the Continent, the major burden of logistical support was expected to be progressively assumed by the larger deep-water ports as they were captured and restored to operation. The Normandy area had been chosen as the site of the landings not only because it possessed the
best combination of features required for an assaulting force, including proximity to the port of Cherbourg, but also because it lay between two other groups of ports—the Seine and Brittany groups—permitting operations to develop toward one or the other. The OVERLORD planners actually expected to rely completely on the Normandy and Brittany groups to develop the required discharge capacity for the Allied forces to D plus 90, and their plans for the rehabilitation of the ports in the lodgment area were made accordingly.
Operating the continental ports was to be a Transportation Corps function, restoring them was the responsibility of the Corps of Engineers. In the final Communications Zone plan this reconstruction work was given a priority second only to the development of beach installations.38 Planning for this task fell mainly to the Construction Division of the Office of the Chief Engineer, ETOUSA. U.S. participation with the British in this planning for port salvage and repair began in July 1942, immediately after the activation of the European theater, when American representatives attended meetings of the ROUNDUP Administrative Planning Staff. General Davison, chief engineer of the theater, suggested the magnitude of the task of rehabilitating the European ports when he said that it could “best be visualized by imagining what would have to be done to place back in operation the ports of Baltimore, Md., Portland, Me., Portland, Oreg., Mobile, Ala., and Savannah, Ga., plus ten smaller shallow-draft U.S. ports, assuming that these ports had been bombed effectively for two years by the R. A. F., then demolished and blocked to the best of the ability of German Engineer troops.”39 He recommended at that time the creation of specially organized and equipped engineer port construction companies reinforced by engineer general service regiments, and suggested that they be organized with personnel from large U.S. construction firms in the same way that American railways sponsored railway operating battalions. These proposals were forwarded to the War Department, and the theater’s needs in this respect were later met by the formation of units substantially along these lines.
Shortly thereafter preliminary studies were undertaken of the problems involved in reconstructing particular continental ports. No operational plan was available at this early date, and the North African invasion intervened to detract somewhat from planning for continental operations. But the ROUNDUP planning staff continued its work throughout the winter of 1942, and early in 1943 a subcommittee on port capacities in northwest Europe was organized under the chairmanship of a British officer, Brigadier Bruce G. White. This committee eventually extended its investigations to the ports along the entire coast of northwest Europe from the Netherlands to the Spanish border.
With the establishment of COSSAC in 1943 the port committee was renamed, but its membership remained virtually unchanged. U.S. engineers still did not know definitely which ports they would be responsible for, but a great amount of preliminary planning was accomplished, and a mass of pertinent data was collected on the various ports. Procedure for the initial occupation of ports was worked out,
and spheres of authority were defined, fixing responsibility for the Engineers, the Navy, and the Transportation Corps. In October 1943 a Joint U.S.-British Assessment Committee drew up an analysis of capacity for each port in western Europe. This included draft, tonnage, operating plant, and weather data. For example, a port reconstruction estimate for Brest, which was expected to be one of the major American points of entry as it had been in World War I, contained a full description of the port, statistics on its prewar operations, estimates of probable demolitions and obstructions and of the port’s capacity, plans for reconstruction, including a timetable for such work, a schedule for the intake of cargo, and a mass of technical data, including graphs, charts, maps, and photos. The Office of the Chief Engineer eventually prepared detailed plans before D Day for eighteen ports in the Normandy and Brittany areas.40
The actual work of rehabilitating the captured ports was to be assigned to organizations specifically designed for this purpose—port construction and repair groups, or PC&R groups. The headquarters and headquarters companies of these groups comprised a nucleus of specialists trained in marine construction, and included a pool of heavy construction equipment together with operators. This nucleus was to be supplemented by engineer service troops and civilians to provide the necessary labor and, according to need, by dump truck companies, port repair ships, and dredges. The port construction and repair group with its attachments thus constituted a task group, tailored for the specialized mission of restoring ports, much as the engineer special brigades were organized for the task of developing the beaches.
The equipment requirements for port reconstruction were difficult to estimate in advance, and little attempt was made to analyze and determine the requirements for individual ports. Instead a stockpile of materials was created, and estimates were made of the necessary repair and construction materials for a fixed length of quay, assuming a certain degree of destruction. These estimates were used to develop standard methods of repair that would be generally applicable to all types of repair work in French ports. Apart from an initial representative list of basic materials and equipment accompanying the repair groups, reconstruction materials were to be ordered to the Continent after the capture and reconnaissance of each port.
The reconnaissance was to be an important preliminary to the rehabilitation of a port, and the composition of the reconnaissance party and its specific mission were planned long in advance. Normally the reconnaissance team was to consist of representatives of the COMZ G-4, the Advance Section, the chiefs of engineers and transportation, and occasionally SHAEF. Upon capture of a port this team had the mission of surveying it for damage to facilities, locating sunken ships and other obstructions, preparing bills of material, deciding the extent and methods of repair, determining the availability of local or salvageable materials, and arranging for the phasing in of the required PC&R units for the actual reconstruction work. The reconnaissance team would therefore determine the degree of
rehabilitation to be undertaken and the initial course of the reconstruction program.41
Several factors had to be taken into consideration in planning the reconstruction of a port and arriving at its estimated capacity. Among them were its prewar capacity and use, the known and assumed damage to the port when captured, and the ability and availability of Army and Navy Engineer units. The damage factor was by far the most variable and unpredictable. For planning purposes, however, certain assumptions had to be made. It was figured, for example, that up to 90 percent of the existing suitable quayage would be initially unusable. Of this, half was expected to be in such condition that it could be repaired fairly quickly or in a matter of days, and the remainder was expected to require varying amounts of work or be beyond repair in any reasonable time. It was also assumed that all craft in the harbors would be sunk, cargo-handling equipment destroyed and tipped into the water, most of the buildings in the port area demolished, road and railway access blocked with debris, entrances to ports and lock chambers blocked and all locks demolished, and water and electric services broken. In addition, it was anticipated that extensive dredging would be necessary in some cases to allow the entrance of anything but the shallowest-draft vessels into waters that had undergone four years of silting.42
By D Day detailed plans were complete for the rehabilitation of Cherbourg, Grandcamp, Isigny, St. Vaast, Barfleur, and Granville in the Normandy area, and of St. Malo in Brittany. (See Map 4.) Cherbourg was the only large port in this group and was the first major objective of the American forces. Except for Granville, all the others were very small and possessed discharge capacities of only a few hundred tons per day. Another Normandy port—Carentan—had been rejected as having a potential too meager to warrant the effort required for its rehabilitation. All were scheduled to be opened by D plus 30, and their restoration was therefore the responsibility of the Advance Section. The schedule for the opening of these ports and their estimated initial discharge capacities were as follows:43
| Port | Opening Date | Tonnage at Opening |
| Isigny | D plus 11 | 100 |
| Cherbourg | 11 | 1,620 |
| Grandcamp | 15 | 100 |
| St. Vaast | 16 | 600 |
| Barfleur | 20 | 500 |
| Granville | 26 | 700 |
| St. Malo | 27 | 900 |
Headquarters, Communications Zone, meanwhile made plans for the later reconstruction of the Brittany ports, the schedule for which was as follows:
| Port | Opening Date | Tonnage at Opening |
| Brest | D plus 53 | 3,240 |
| Quiberon Bay | 54 | 4,000 |
| Lorient | 57 | 800 |
Although plans were made for phasing equipment and the required Engineer and TC units into the Brittany ports and a schedule was written for their opening, the ports of Normandy naturally enjoyed
the first priority in development, and the plans for its six ports plus St. Malo were worked out in much greater detail before D Day.
Of these seven ports all except Cherbourg were tidal, drying out completely at low water. Most of them had a mud- or sand-bottomed basin and two or three quays which were entirely tidal, and at high water they could accommodate only vessels drawing a maximum of thirteen or fourteen feet.44 In this respect they were typical of the French ports along the English Channel and the Bay of Biscay, where tide and weather conditions had required the construction of massive breakwaters, locked basins, and channels, in contrast with ports in the United States where such elaborate paraphernalia were unnecessary.
St. Malo was known to have a large amount of locked quayage, but it could be blocked easily and had poor rail clearance facilities. Consequently it was considered suitable only for operations employing amphibian trucks (DUKWs) for at least the first ninety days. Granville, on the west coast of Normandy, had somewhat better facilities than the other ports. In addition to quayage in its Avant Port, where vessels could “dry out” (that is, beach at ebb tide, unload, and then float out on the next tide), Granville had a locked or “wet” basin with berthing facilities that could accommodate seven 4,000-ton ships of 14-foot draft simultaneously. The Allies did not count on immediate use of the wet basin, for the enemy was expected to destroy the lock gates and sink blockships in the chamber. But with the removal of obstacles they planned to dry out coasters at the inner quays and to utilize Granville for the reception of coal and ammunition.45
Although the movement of craft into and out of these “minor” ports would be restricted by the tide, they at least offered some protection from stormy weather, and the desperate need for discharge capacity in the early phases appeared to warrant bringing them into use. The total discharge capacity of these six minor ports was not great. At D plus 30 it was scheduled to be 4,500 tons per day. At D plus 60, with the small Brittany port of Lorient added, they were to develop a capacity of 7,700 tons, and at D plus 90, 10,650 tons.46 As for clearance facilities, all the ports had good road connections, but only Granville had first-class rail clearance. All the other minor ports would have to be cleared by motor transport.
The division of responsibilities and the procedure for restoring and operating the ports were defined in minute detail. Work of a more strictly marine nature was assigned to the British and U.S. Navies, the former assuming responsibility for minesweeping the harbors, and the latter for removing obstacles such as sunken blockships in the channels and along quays and for making hydrographic surveys. Reconstruction or enlargement of discharge facilities was an Army Engineer responsibility, and the plans for the first six weeks were written in full detail by the Advance Section. The ADSEC plan provided that a reconnaissance party should debark on D plus 3 and successively examine the condition of port facilities at all the minor ports, beginning at Isigny. As these preliminary surveys were completed, the commanding officer of the port construction and repair group was to draw up a definite
reconstruction job schedule to meet the planned port capacity. The first repair work was to get under way on D plus 6 at Isigny and Grandcamp with the arrival of the headquarters of the 1055th PC&R Group and work parties consisting of advance elements of the 342nd Engineer General Service Regiment. Upon completion of its task the entire group was to proceed in turn to St. Vaast, Barfleur, Granville, and St. Malo for similar projects.47
While repair and construction might continue for several months, as at Cherbourg, the Transportation Corps was to start operating the ports as soon as the unloading of cargo could begin. For this purpose the 11th Major Port was attached to the Provisional Engineer Special Brigade Group at OMAHA to handle pierhead operations at the MULBERRY and to operate the small ports of Isigny and Grandcamp.48 It was also to furnish a detachment to the 1st Engineer Special Brigade to operate the small port of St. Vaast (and eventually Carentan, as it turned out) in the UTAH area. The operation of Barfleur, Granville, and St. Malo was to be supervised by the 4th Major Port at Cherbourg. Another major port, the 12th, was to take over the operation of Granville and the ports in the vicinity of St. Malo. The Allies hoped that St. Malo itself could be developed to a capacity of 3,000 tons per day, and the St. Malo area, including Cancale and St. Brieuc, to 6,000 tons, and thus relieve beach operations at OMAHA and UTAH. They counted on the St. Malo development to provide all the tonnage capacity necessary to sustain the Third Army, and possibly even to debark some of its personnel.49
Since the minor ports possessed only limited capacities and were rather uneconomical to operate, their development was never intended to be more than a stop-gap measure designed to meet a portion of the discharge requirements in the period before the full potential of the larger ports was realized. Plans for their restoration were completely overshadowed by those made for Cherbourg. This port was expected to handle 6,000 tons at D plus 30, 7,000 at D plus 60, and 8,000 at D plus 90, and was to exceed in capacity the combined tonnage of the six minor ports throughout the first 60 days. Even Cherbourg was to have but a temporary importance for U.S. forces, for plans were tentatively made to turn the port over to the British after a short time, and to route the major portion of American cargo through the Brittany ports and later through others farther up the Channel. Cherbourg, however, played a wholly unexpected role in the support of U.S. forces and eventually ranked as one of the big three of the continental ports.
The relatively high tonnage targets for Cherbourg appear optimistic in view of the port’s peacetime performance. Cherbourg, home of the French luxury liner Normandie, had been primarily a passenger port and a naval base. It had handled an average of less than 900 tons per day, ranking twenty-second among all the
Aerial View of Cherbourg. Digue de Querqueville, 1; Naval Arsenal, 2; Nouvelle Plage, 3.
French ports in cargo tonnage. Warehouse and storage facilities were correspondingly small, and cargo-handling equipment was in keeping with a port that specialized in passenger trade rather than freight.50
Built up over a period of two hundred years, Cherbourg’s port facilities were essentially completed in the early 1920’s, but at the outbreak of World War II they were still undergoing improvements designed to facilitate the berthing of the largest ocean liners. Cherbourg’s harbor is artificial, consisting of a double set of breakwaters which form both an inner and outer roadstead, one known as the Petite Rade and the other as the Grande Rade. The only facilities in the outer harbor consisted of tanker berths along the Digue de Querqueville, the western arm of the outer breakwater, which the Allies intended to restore for the bulk reception of POL. Otherwise the outer harbor was chiefly an anchorage, affording some protection to shipping, but too rough in stormy weather to permit lighterage operations. The inner roadstead was workable in all weathers. Both had sufficient depth at all variations of the tide to receive the largest ocean liners. The Petite Rade, or inner harbor, contained almost all of the port’s berthing
facilities, most of which were concentrated along the western and southern sides. The entire western side of the port was occupied by the great Naval Arsenal, consisting of repair shops, drydocks, and maintenance facilities grouped around its three basins—the Avant Port, Bassin Charles X, and Bassin Napoléon III—and including additional berthing facilities at the Quai Homet and along the Digue du Homet, the western jetty enclosing the inner harbor. This area alone was expected to provide discharge facilities for 5 Liberty ships, 2 train ferries, 24 coasters, and 2 colliers.
Just south of the main arsenal installation lay the seaplane base and its three small basins—the Bassin des Subsistences, Avant Port, and Port de l’Onglet—which were expected to provide berths for 13 coasters. Adjoining this area to the southeast was a broad bathing beach known as the Nouvelle Plage, believed to be ideal for unloading vehicles from LSTs. Immediately to the east of this beach and directly in the center of the harbor lay the entrance channel to the Port de Commerce, consisting of two basins (the Avant Port de Commerce and the Bassin à Flot) which jutted deeply into the heart of the city. These two basins were planned to accommodate 17 coasters and 2 LSTs with tracks for the discharge of railway rolling stock.
Dominating the entrance to these basins was the large Darse Transatlantique, the deepest portion of the harbor, where the Quai de France and the Quai de Normandie provided berthing for large passenger liners, and where discharge facilities were now to be provided for 7 Liberty ships, 2 LSTs carrying rolling stock, and a train ferry. A large tidal basin in the southeast corner of the port was believed to be suitable for the reception of additional vehicle-carrying LSTs.
In all, the port was expected to provide berths for 12 Liberty ships, 18 LSTs (6 of which would deliver rolling stock), 56 coasters, 2 tankers, 3 colliers, and 1 train ferry. In addition, the harbor of course offered alternative anchorage for other shipping which could be worked by lighters—either DUKWs or barges. When these facilities were fully developed the port was expected to attain a daily discharge capacity of 8,000 tons.51
Despite the assumption that the enemy would carry out a systematic destruction of Cherbourg before surrendering it, Allied planners hopefully scheduled the opening of the port and the start of limited discharge operations three days after its capture. The procedure for restoring Cherbourg and bringing it into operation was similar to that described for the minor ports. In the three days following its capture the Royal Navy was to sweep mines from the harbor, and U.S. naval salvage units were to begin removing blockships. Rehabilitation of the port’s inshore facilities meanwhile was to be undertaken by the 1056th Port Construction and Repair Group, with attached elements of an engineer general service regiment, an engineer special service regiment, and an engineer dump truck company. A reconnaissance party of this organization was scheduled to debark at UTAH Beach on D plus 5, proceed to the port on D plus 8, and immediately establish priority of debris clearance in the port area. In conjunction with the Navy salvage party, it was to establish priority for ship salvage and removal operations for approval of the port commander. It would also decide on the
schedule for initial quay repair jobs and examine locations where initial cargo discharge from DUKWs, barges, and LSTs could begin.
The actual rehabilitation work was to begin the second day after capture (D plus 10), early priority being assigned to such projects as debris clearance from the Quai Homet area, preparation of LST landing sites on the Nouvelle Plage, and construction of a tanker berth at the Digue de Querqueville on the west side of the outer harbor. By D plus 11 progress on these first projects was expected to be sufficient to permit the unloading of about 1,600 tons of cargo by a combination of DUKWs and barges unloading from Liberties and coasters, the unloading of at least one docked coaster direct to a usable quay, and the discharge of 840 vehicles per day from LSTs at the Nouvelle Plage. By the fourth day the Allies planned to boost unloading to about 3,800 tons, and by the tenth to about 5,000 tons. The great bulk of this discharge was to be carried on by DUKWs and barges working Liberty ships and coasters at anchor. In fact, only one coaster berth and four Liberty berths were expected to be in use at the end of the first month of operations, and direct ship-to-shore discharge consequently was expected to account for only a fraction of total discharge in these early weeks.
Some conception of the minute detail and scope of preparations for the rehabilitation of the ports can be gained from a glance at the engineer reconstruction plans. In sheer bulk the ADSEC engineer plan outweighed that of all other services combined, comprising two thick volumes of data on the Normandy ports. These included an analysis of their facilities, a schedule of reconstruction, and a detailed catalogue of equipment and material needs. The length and width of every quay, the depth of water alongside, the nature of the harbor bottom, the number and types of cranes, the capacities of berths, road and rail clearance facilities, all were set down in enclosures to the plan. Next, every reconstruction project was defined and given a priority, and units were phased in to undertake these jobs in prescribed order on specific days. On the basis of the above data, the ADSEC planners estimated the type and number of craft that could be accommodated and the tonnage discharge targets that should be met on each day by the beaching of vessels, by DUKW, coaster, and barge discharge, and by direct unloading from either coasters or deep-draft ships. In meticulous detail they drew up lists of materials needed in the reconstruction, specifying the exact quantities of hundreds of items from bolts and nails, ax handles, valves, washers, and turnbuckles in quantities weighing only a few pounds, to heavy hoists, tractors, sandbags, and cement, weighing many tons. The ADSEC plan scheduled twenty-one projects to be started by D plus 31, establishing the days and priority in which they were to be undertaken, specifying the crews available for each job, and the time in which they were to be completed. While it was unlikely that this clocklike schedule would be followed to the minute in view of the many unforeseeable circumstances, plans nevertheless had to be made on the basis of the most optimistic forecast of tactical progress in order that logistical support should not fall short of requirements.
A picture of the personnel and equipment required to operate the ports is afforded by the Transportation Corps plan. For the beach areas alone, including the minor ports in the vicinity, the basic units
allotted included 1 major port headquarters (the 11th), 10 port battalion headquarters, 48 port companies, 1 harbor craft service company, 7 quartermaster truck companies, and 19 amphibian truck companies. Cherbourg was assigned 1 port headquarters (the 4th), 6 port battalion headquarters, 20 port companies, 2 harbor craft service companies, 1 port marine maintenance company, and 4 amphibian truck companies. Floating and nonfloating equipment needs at the beaches included 950 DUKWs, 16 tugs, 7 sea mules, 66 barges, and varying numbers of cranes, tractors, trailers, and various types of boats. Cherbourg was to be furnished 200 DUKWs, 176 barges, 38 tugs, 11 sea mules, a floating drydock, and various crane barges, landing stages, and boats. These items were solely for harbor use. On shore there were additional requirements for 69 cranes of various sizes and types, 30 derricks, plus conveyors, trailers, and tractors.52 In addition to these elaborate plans for the development of the port’s discharge capacity the Communications Zone plan scheduled the introduction of railway equipment to meet the corollary requirement of developing Cherbourg’s clearance facilities.
Plans for the rehabilitation of the Brittany ports were written in far less detail, since the final decision regarding the development of that entire area was to depend on circumstances following the battle of Normandy. No specific units were named to handle reconstruction and operation of the Brittany ports, although estimates were made as to types of units and quantities of equipment needed to bring Brest, Quiberon Bay, and Lorient into operation. Plans for the Brittany ports had undergone several alterations. Before April 1944 they contemplated the development of St. Nazaire, Morlaix–Roscoff, St. Brieuc, Concarneau, and Le Pouliguen in addition to St. Malo, Lorient, and Brest. With the acceptance of the Quiberon Bay (CHASTITY) project early in April the final COMZ plans provided for the restoration of only Lorient, Brest, and St. Malo with its adjacent beaches at Cancale, and the development of Quiberon Bay. These four ports were planned to develop a daily capacity of about 17,500 tons.53
The plan that finally evolved for the development of Quiberon Bay differed substantially from the original concept. A study of the area revealed that while the bay itself provided ample anchorage of required depth, and while the inland transportation net could be developed to needed capacity, bad weather conditions barred the use of lighters to unload ships in the winter. The development of deep-water berths was likewise found to be impracticable since the wide tidal range and the gentle slope of the sea bottom near the shore would have required the construction of extremely long piers. The answer to the problem lay rather in the Auray River, which flows into Morbihan Gulf and Quiberon Bay from the north. This estuary had scoured a narrow channel almost eighty feet deep near the small fishing village of Locmariaquer, providing deep and sheltered water where large ships could lie alongside piers or landing stages and discharge their cargo, and anchorage from which lighterage operations could be safely conducted. (Map 8)
As finally evolved the plan called for moorings for thirty deep-draft vessels in the deep-water “pool,” and a landing stage designed to float up and down with the
Map 8: The CHASTITY Plan
tide providing berths for five Liberty ships at the edge of the deep-water anchorage. Two fixed-construction causeways were to extend across the tidal flat from the shore to the landing stage. In addition a floating pier, constructed of naval lighterage pontons, was planned south of the landing stage, and an existing mole with rail connections farther north was to be extended into deep water to make possible the handling of heavy lifts. These facilities were expected to give the port a capacity of 10,000 tons per day.
The CHASTITY project had much to commend it. Among its attractive features was the fact that it made the most of an existing natural advantage—that is, sheltered water—and that it required only a fraction of the labor and materials that were to go into the artificial ports or MULBERRIES. Furthermore, no special design or manufacturing problems were involved, for all the components of the piers and landing stage consisted of standard materials and equipment already available.54
The port capacities given above were those embodied in the final OVERLORD plan, and represented substantial revisions made in March and April 1944, when it was realized that additional discharge capacity would be needed. As plans stood at that time the port situation remained very tight for both the OVERLORD and post-OVERLORD periods and imposed a considerable rigidity in logistical plans, for every port and beach would be forced to work to capacity. In fact, it was estimated in March that port capacities would actually fall short of U.S. tonnage needs at D plus 41. By that date the daily requirements would total approximately 26,500 tons, while discharge capacities were estimated to reach only 20,800.55
In March and April the entire problem had been restudied with a view toward making up the recognized deficiencies. The substitution of the CHASTITY project for St. Nazaire and the other minor Brittany ports was a partial solution. But the Brittany ports were not scheduled to come into use until after D plus 50. Measures were also taken in March to prolong the life of the MULBERRIES. In addition, estimates were revised, first, of the time required to capture the ports, and second, of the time required to open the ports. At the same time the estimates of their tonnage capacities were increased. Cherbourg’s maximum capacity, for example, was boosted from 5,000 to 8,000 tons. Its capture was more optimistically scheduled for D plus 8 instead of D plus 10, and the time required for its opening changed from ten to three days. Cherbourg was thus scheduled to receive cargo on D plus 11 instead of D plus 20, and in greater volume. As a result of similar alterations in the schedule for the other ports the planned tonnages of the Normandy ports were increased by over 4,000 tons per day.
Two encouraging developments made these revisions possible. Experience in the Mediterranean, particularly at Philippeville and Anzio, indicated that ports could be brought into operation and capacities developed much faster than had been originally believed possible. In addition, both the British and Americans had greatly improved their equipment and engineering techniques for the reconstruction of destroyed ports. All these developments were reflected in the final plans. The Normandy and Brittany port plans as they
Beach and Port Plans for Operation OVERLORD
| Port or Beach | Opening Date | At Opening | Discharge Capacity (in Long Tons): | |||
| D plus 10 | D plus 30 | D plus 60 | D plus 90 | |||
| Total | 14,700 | 27,200 | 36,940 | 45,950 | ||
| OMAHA Beach | D Day | 3,400 | 9,000 | 6,000 | 5,000 | 5,000 |
| UTAH Beach | D Day | 1,800 | 4,500 | 4,500 | 4,000 | 4,000 |
| Quinéville Beach | D + 3 | 1,100 | 1,200 | 1,200 | 1,000 | 1,000 |
| Isigny | D + 11 | 100 | 0 | 500 | 500 | 500 |
| Cherbourg | D + 11 | 1,620 | 0 | 6,000 | 7,000 | 8,000 |
| MULBERRY A | D + 12 | 4,000 | 0 | 5,000 | 5,000 | 5,000 |
| Grandcamp | D + 15 | 100 | 0 | 300 | 300 | 300 |
| St. Vaast | D + 16 | 600 | 0 | 1,100 | 1,100 | 1,100 |
| Barfleur | D + 20 | 500 | 0 | 1,000 | 1,000 | 1,000 |
| Granville | D + 26 | 700 | 0 | 700 | 1,500 | 2,500 |
| St. Malo | D + 27 | 900 | 0 | 900 | 2,500 | 3,000 |
| Brest & Rade de Brest | D + 53 | 3,240 | 0 | 0 | 3,240 | 5,300 |
| Quiberon Bay | D + 54 | 4,000 | 0 | 0 | 4,000 | 7,000 |
| Lorient | D + 57 | 800 | 0 | 0 | 800 | 2,250 |
were written into the final COMZ and ADSEC plans in May are summarized above.56
These final estimates were regarded as adequate to meet the needs of U.S. forces in the first three months. But even these schedules were subject to last-minute revision. With the discovery in May of an additional German division in the Cotentin peninsula the tactical plans of the VII Corps had to be amended only a few days before D Day. The estimated capture date of Cherbourg was changed from D plus 8 to D plus 15, with a resultant loss of tonnage, estimated to total 34,820 tons for the period D plus 11 to D plus 25.57
Unfortunately the anxieties and uncertainties attending port planning were not to end with the establishment of a lodgment on the Continent. Port discharge was to become one of the most frustrating limiting factors of the continental operation and was to persist as a major logistic problem for fully six months after the landings.
Troop Build-up and Replacements
Closely related to the problem of port and beach capacities was the matter of the continental troop build-up. The OVERLORD operational plan prescribed that in the American zone the assault and immediate follow-up would consist of three infantry and two airborne divisions, together with the necessary supporting troops, and that additional preloaded forces were to land on D plus 1 and 2.
| Date | Force | Personnel | Vehicles |
| Total | 1,338,900 | 250,000 | |
| D Day | “O” (OMAHA) | 29,714 | 3,241 |
| D Day | “U” (UTAH) | 30,452 | 3,569 |
| D to D + 1 | “B” (Follow-up) | 26,492 | 4,431 |
| D + 1 to D + 2 | Preloaded Build-Up | 43,472 | 6,063 |
| D + 2 to D + 14 | Build-Up | 369,061 | 53,352 |
| D + 15 to D + 90 | Build-Up | 839.709 | 179,344 |
Thereafter the transfer of forces to France was to be accomplished by the shuttling of ships and craft between the United Kingdom and the Continent and would be dependent on the repeated use of the same lift and on the speed with which this shipping could make the round trips between the two shores. In the first three months an American force of nearly 1,340,000 men and 250,000 vehicles was scheduled to be moved across the Channel, the build-up target calling for 12 U.S. divisions on the Continent by D plus 30, 16 by D plus 60, and 21 (14 infantry and 7 armored) by D plus 90, together with supporting combat troops, elements of two tactical air commands, and service troops.58
The preloaded forces were organized as follows: Forces O (for OMAHA) and U (for UTAH), approximately equal in size, constituted the initial assault forces, and together totaled about 60,000 men and 6,800 vehicles.59 They were to be loaded in ships and craft along the coast of southern England and were to land on the French beaches on the first tide. Force B, with a strength of about 26,500 men and 4,400 vehicles, formed a follow-up force with various reinforcement units for the V Corps in the OMAHA Beach area. This force was to be assault-loaded in ships and craft in the southwestern English ports and was to land on the second tide of D Day and on D plus 1. In addition, a preloaded build-up force of 43,500 men and 6,000 vehicles, containing units for both beaches, was to embark in the Bristol Channel ports and cross the Channel on D plus 1 and 2. A total of more than 130,000 men and 17,300 vehicles was thus loaded in all the available ships and craft before D Day.
The remaining OVERLORD forces, scheduled to enter the Continent by D plus 90, constituted the build-up proper. This movement depended on the availability of shipping. A statistical summary of the plan is given in the table at top of page.60 After D plus 90, divisions were to arrive in France at the rate of from three to five per
| Date | Divisions | Field Forces | Air Forces | COMZ | Total | Replacements |
| D + 5 | 9 | 172,900 | 8,500 | 41,200 | 222,600 | 6,700 |
| 15 | 11 | 297,200 | 21,900 | 83,500 | 402,600 | 43,600 |
| 25 | 11* | 353,100 | 42,600 | 142,300 | 538,000 | 60,200 |
| 40 | 15 | 453,800 | 79,900 | 235,100 | 768,800 | 95,100 |
| 60 | 16 | 532,400 | 104,500 | 289,600 | 926,500 | 138,800 |
| 90 | 21 | 666,400 | 123,900 | 343,600 | 1,133,900 | 204,800 |
* Two Airborne Divisions withdrawn
month, the majority of them directly from the United States.
Determining the make-up of the force and the order in which the various units should be phased into the Normandy bridgehead posed another problem. The composition of the build-up as between field, air, and service forces is shown in the schedule tabulated at the top of this page.61 It can be seen that the most rapid buildup of divisions was to occur in the first two weeks of the operation, and that the field forces as a whole made up 75 to 80 percent of the assault and initial build-up forces through D plus 15.62 It was natural that the assault and initial build-up forces should be composed primarily of combat units, for the first mission was to secure a beachhead. The field forces, consequently, were allotted the preponderant share of the available lift in the early stages, and whatever service forces other than those organic to the divisions crossed the Channel in these first days, such as the units with the engineer special brigades, were attached to the assaulting corps.
While the prior claims of the field forces in the early stages were fully recognized, it was obviously desirable that service forces should be introduced as early as possible. The need for them would mount rapidly as ports were captured and as tactical progress required the development of the lines of communications. In allocating the available lift there arose the ever-recurring argument as to the proper ratios of combat and service troops. One facet of this eternal conflict has already been seen in the competition between ground and service forces for larger shares of the theater troop basis. In view of shipping limitations, the competition was bound to continue in the allotment of lift and in the preparation of the build-up priority lists.
Desirous of having their forces made up of as many “fighting” elements as possible, field commanders naturally resisted the demand that a larger and larger portion of the troop basis consist of service troops. But modern warfare had brought about a relentless encroachment on the long-favored position of the combat forces in the troop basis, assigning an ever-expanding role to service troops and consequently demanding for them a larger and larger share of the “division slice.”63 Not only did growing mechanization require larger numbers of technicians and multiply the
tonnages and the number of supply items; the growing destructiveness of modern warfare, toward which the heavy bomber had made a large contribution, made it necessary to rebuild a country’s lines of communications as armies moved along.
The competition between combat and service troops for the available lift was pointedly illustrated in January 1944 when the Supreme Command was considering a major alteration in the OVERLORD plan that provided for an enlargement of both the assault area and the size of the attacking forces. One of the officers at a Supreme Commander’s conference at that time expressed apprehension lest, with the changes, the service forces would also request an increase in strength in the early stages. He believed such demands should be resisted. A representative of the service forces thought it necessary to re-emphasize that the requirements for service elements in the early stages must not be underestimated nor neglected. General Eisenhower recognized immediately that with a wider bridgehead the Allies would also have a wider road for the supply of the operation, and he thought it was logical that the strengthening of the assault forces should be accompanied by a corresponding strengthening of the administrative components.64 Whatever force was placed on the Continent had to be a balanced one, and any attempt to introduce excessive combat forces without an adequate build-up of service forces and an increase in supply build-up capacity would reduce the division slice and lessen the support capabilities of the Communications Zone.
In the final plans a force of 340,000 COMZ troops as compared with about 665,000 field force troops was scheduled to be built up in the first three months. The proportion of service troop strength was actually higher, since the field forces themselves contained substantial numbers of organic service units. In the first days COMZ troops were to comprise only 16 to 18 percent of the total force landed. The build-up of service troops was to be stepped up in the second week and would comprise 21 percent of the total on D plus 15, rising to 26 percent on D plus 25 and 30 percent on D plus 40. On the eve of the invasion the troop basis provided for a division slice of 40,000 men, of which 10,000 or 25 percent comprised the COMZ portion.
Logistic planners regarded neither the current division slice nor the rate of service troop build-up as satisfactory. Acutely aware of the logistic demands of the operation, they observed that between D plus 50 and 90 U.S. service forces would be called on not only to support operations then in progress, but to establish bases and lines of communications to support future operations and increasing numbers of troops. Their tasks would include the development of port capacities, the creation of a large depot system, the improvement of roads, and the reconstruction of railways. These jobs were considered abnormally difficult in OVERLORD because of the physical shape of the area, the anticipated change in the direction of advance (south, and then both west and east), and the approach of winter weather. Because the demands on the Communications Zone would be particularly heavy, the planners recommended that in the period D plus 50 to 80 the build-up of COMZ troops should take priority over the buildup of field forces.65
Whether such priority would actually be given depended largely on the course of operations. Meanwhile, the rate at which both combat and service units were to be shipped to the far shore was at least tentatively prescribed in what were known as Buildup Priority Lists. The U.S. forces in the OVERLORD operation consisted of several thousand units and detachments of varying size, many units being broken into two or more echelons for the movement across the Channel. Scheduling their shipment in the order best designed to meet both tactical and logistical needs was itself a vital element of the operational plan.
To prepare these lists, essentially a responsibility of the tactical commands, was a laborious task involving many considerations. The basic limiting factor governing the speed at which U.S. forces could be built up on the Continent was the available lift. Estimates on the course of operations, particularly the rate of advance, further determined the types and proportions of combat and supporting troops required on the far shore. Similarly, a forecast of areas progressively to be occupied by U.S. forces in France was a factor in determining the number of advance airfields to be established by the air forces. These estimates, by indicating the number of troops requiring logistical support, provided a basis for calculating the buildup of service units. A number of other considerations bore heavily: the initial lack of port and rail facilities called for heavy reinforcement in Engineer and Transportation Corps units; the initially independent operations of the V and VII Corps in the assault necessitated that sizable service elements be assigned to the corps in the early stages; and the threat of enemy air attack against large forces concentrated in a small area required a large number of antiaircraft units and the early establishment of advance airfields.
Many compromises eventually had to be made. In practice the field force, air force, and COMZ planners were allotted a proportion of the expected daily lift and were directed to name specifically the troop units which they desired included in each day’s build-up. Finally, these requirements were arranged in a single list for priority of embarkation and movement.
Partial lists were prepared initially by the two assault corps, the V and VII. Since the assaults were to be carried out several miles apart, a more than normal responsibility for the conduct of the operation in its early stages devolved upon the corps commanders. The two corps accordingly were given considerable independence in their planning, and troops following the assault waves were to be phased so far as practicable according to priorities desired by the corps commanders, The task of integrating the two corps lists and extending them for the later build-up was performed by the planning staffs of First Army and 1st Army Group. First Army’s list, called List A, established the sequence of movement only through D plus 14 and, since First Army was in complete control of the entire beachhead in this phase, included only the units assigned or initially attached to that headquarters. The list for the subsequent build-up of U.S. forces assigned to First Army, Third Army, the Ninth Air Force, and the Communications Zone, which were expected to move to the Continent between D plus 15 and 90, was prepared by 1st Army Group and was known as List B. The completed lists showed in their anticipated order of movement priority
all units or portions of units which were to move separately, their personnel and vehicle strength, and their assignment. The preparation of the lists involved some of the most agonizingly detailed coordination of the OVERLORD planning, for there were endless changes in the designation, type, number, and composition of units. While the First Army list was firm early in April, it was not until much later that agreement with the various headquarters involved was reached on the 1st Army Group list.
Late in May the receipt of information concerning added enemy strength in the Cotentin set off a chain reaction that illustrated how last-minute changes in tactical plans could affect all aspects of logistic arrangements. Anticipating increased resistance in the VII Corps sector, the planners concluded that progress would probably be slower, that Cherbourg would be captured later than originally estimated, and that there would be a delay in developing the discharge capacity of UTAH Beach to the maximum. It was all the more imperative that communications between the two corps be established at an early date. The expected delay in the capture of Cherbourg made it possible to phase back by five to seven days the units scheduled to open that port. This in turn freed sufficient lift to permit the earlier transfer of an additional infantry division. To meet the expected need for additional combat strength, therefore, the First Army commander directed that the service troops in question be phased back and that another division (the 79th) be brought in over UTAH Beach at about D plus 8. The Advance Section opposed the change, and warned that the resultant delays in the reconstruction of Cherbourg and of the railways might seriously affect its ability to support the operation.66 The change was made, nevertheless, and proved to be but the first of many alterations in the build-up schedule.
It was realized from the beginning that such alterations would have to be made, particularly after the operation got under way. The projected build-up was based on certain assumptions as to the course of the operation. However carefully these estimates might be made, the actual flow of troops to the Continent would have to meet the changing requirements dictated by the course of the battle, and in all probability would differ from the planned phasing. Provision for such departures from the planned build-up was made in the creation of separate control machinery known as the Buildup Control Organization, or BUCO, the planned operation of which is outlined in the next chapter. Meanwhile the staff of 1st Army Group also prepared an alternative build-up list to be used in the event that the progress of U.S. forces in Normandy was considerably slower than promised in the operational plan. This alternative list provided for the assignment of an appreciably higher proportion of the available lift to combat units and consequently a more rapid build-up of combat forces at the expense of supporting and service troops. It provided for the movement of twenty-one divisions to the far shore by D plus 65 instead of D plus 88 as scheduled in the accepted list, on the assumption that if
progress was slower the lines of communications would be shorter and fewer service troops would be required.67
The movement of replacements and the establishment of a replacement system on the Continent constituted an essential part of the OVERLORD build-up plan. The responsibility for drafting such a plan rested with the Replacement System, a separate theater command headed by Col. Walter G. Layman. The lack of a plan as late as the end of April caused some apprehension in higher headquarters.68 But a plan to guide the movement of replacements and replacement installations to the Continent was published in mid-May as an annex to the Communications Zone plan. It provided for the transfer of more than 200,000 replacements to the Continent in the first ninety days.
The replacement plan followed the three-phase scheme which was common to all OVERLORD planning. During Phase I (D to D plus 14) the replacement system on the Continent was to be operated by First Army. Three separate replacement battalions were to be attached to First Army initially, one in support of each corps (V, VII, and XIX), to handle the processing of replacements requisitioned in advance. On about D plus 10 a replacement depot with two additional battalions was to cross to the Continent and assume control of all five battalions operating with the First Army. An operational reserve of 5,000 replacements was to be shipped to the depot immediately from the replacement pool in the United Kingdom.69 In Phase II (D plus 15 to 41) the over-all control of the replacement system was to be exercised by the Advance Section. In this period an additional depot with four battalions was to be established on the Continent; two battalions were to be brought in for the support of the Third Army; and an armored force replacement battalion was to be established to form the nucleus of an armored force depot. The phasing in of the remaining replacement installations, including three more depots with eleven battalions, was to be completed in Phase III (D plus 42 to 90). All depots were not of the same type, nor in direct support of the armies. Some served as replacement stockage depots, some as reception depots, and others were for casuals or for training.70 All were to move to the Continent according to a prearranged schedule, although this was subject to change as were all build-up plans.
Long before D Day the theater worked out a requisitioning procedure for the normal operation of the replacement system. But this procedure was not counted on to fulfill the needs of the initial stages of the invasion, for it was believed to be incapable of responding quickly enough to the demands which heavy initial casualties were expected to cause. Large numbers of replacements would be needed quickly, and the existence of a water barrier between the stockage pools and requesting units, causing both transportation and communications difficulties, was expected to create a great handicap to the expeditious filling of requisitions. Even the establishment of three replacement battalions within the first week was not expected to meet the earliest demands.
Two methods were devised to meet the problem in the first fifteen days. To provide for replacement needs in the first five days of the operation an initial over-strength of 2,500 men was authorized each assault division, and proportional over-strengths were also authorized the engineer special brigades. These over-strength increments were attached to the units in the United Kingdom and underwent training with them. At invasion time they were held in readiness on the near shore to be sent forward on a prearranged schedule.
Beginning on D plus 5, when the over-strengths were expected to be exhausted, and continuing through D plus 14, replacements were to be provided in “packages” made up in advance. Each package was to contain 250 men organized into platoons and squads and commanded by officers and noncommissioned officers who were also replacements. Members of the ETOUSA adjutant general’s staff had conceived the idea, proposing that the packages be formed by arm or service, and that their make-up be based on casualty experience in North Africa. An infantry package, for example, would consist entirely of infantrymen of varying specialties, such as riflemen, cannon crewmen, mechanics, antitank gunners, heavy weapons crewmen, and so on.
The basic idea of the package system was eventually adopted, although in modified form. First Army substituted its own estimates on casualties, and rejected the idea of standardized packages. Instead, advance requisitions were submitted, based on estimated losses by unit, and replacements were then grouped into increments of 250 men for processing and shipment. The packages varied therefore, depending on the type of unit for which they were intended, some being made up entirely of infantry, others of mixed branches, and each package was earmarked for specific division or corps units. After D plus 14, replacements were to be obtained by the normal requisitioning procedure, by which they would be processed by the various replacement battalions then operating on the far shore.71
To stock even approximately correct numbers of each type of replacement before D Day was a difficult task, for it depended entirely on the accuracy of loss estimates. Estimates had to be made several months ahead of actual need so that the War Department could plan its training program sufficiently in advance and establish the necessary shipping priorities. Initially the War Department authorized a specific allowance in the theater troop basis in order that an adequate stockage of replacements might be on hand for the invasion. On the basis of estimated losses from all causes in the first sixty days the theater was permitted to build up its pool of replacements to 84,110 men by 1 June 1944. On that date the Replacement System actually had a total of 76,026 men plus the 5,300 allocated to over-strength increments for assault units, making a total of 81,326.
The army group commander had been called on to submit replacement requirements
for OVERLORD in January 1944. Before submitting his figures he first had to estimate casualties—a process that involved some complex calculations. The average losses of any one campaign could not be used, for example, since casualty rates fluctuated in the course of operations, with the heaviest losses occurring in the assault period. For purposes of calculation the first 150 days of the operation were therefore divided into five thirty-day periods. Among the factors involved in estimating casualty rates in these phases were the strength of the enemy and estimates of his capabilities, the type of action expected, the terrain and weather, the probable number of drownings in the first days, and the expected nonbattle casualties. Additional estimates had to be made of the percentage of men that would be killed, wounded, and missing, and of the percentage of wounded that could be expected to return to duty in 30, 60, 90, or 120 days. Finally, it was necessary to estimate the need for replacements in each branch and in each occupational specialty. Studies made in October 1943 concluded that 62 percent of all replacements would have to be infantrymen. In February 1944 this figure was raised to 64.3 percent, and shortly before D Day it was again raised.72 Obviously the problem of determining personnel requirements was full of unpredictables, and only the experience of actual combat would test the validity of these calculations.
The replacement problem did not end with the acceptance of working estimates of casualty rates and ratios for the various branches. Obtaining the needed number of replacements was not a simple matter of requisitioning, for the supply of manpower on which the theater could draw was by no means unlimited. The War Department warned the theater in January 1944 that the manpower situation was already critical and that conservation would have to be practiced. There was a shortage of several hundred thousand men in the planned strength of the army, a shortage that had been aggravated by the tendency to discharge men who were still capable of rendering useful service. General Marshall urged at that time that men who were not physically perfect be retained in limited-assignment positions where possible and that able-bodied men be released for combat duty.73 The kind of deficiency that had developed is illustrated by the paratroop replacement shortage. Because of the lack of qualified volunteers, two parachute infantry regiments and two glider regiments had to be deactivated in the United States in order to meet the theater’s requirements in these categories.74
The manpower situation saw no improvement as D Day approached. In March the War Department considered phasing back by one month the flow of replacements to the United Kingdom. But after a restudy of manpower needs the theater concluded that all personnel requisitioned would be needed if OVERLORD was to be launched as planned. In fact, the theater estimated that even with the current flow of replacements a pool adequate for only 60 days could be built up, and that the reserve would be completely exhausted in 120 days. First Army thought the flow of men should be increased rather than curtailed. Meanwhile the theater complied with War Department
directives and initiated a conservation program that stressed the economical use of manpower and extensive utilization of limited-assignment personnel.
The War Department again applied the spurs to this program in April, and in the following month both the theater and the zone of interior took further economy measures. In May all SOS replacements were frozen in the 10th Replacement Depot in the United Kingdom in order to screen out men suitable for duty with the field forces. In addition the theater commander ordered that all physically qualified infantry officers and enlisted men in noninfantry units not required for staff positions be made available as infantry replacements. At the same time the War Department cut in half the allotment of basic privates in T/O organizations to release qualified men to the replacement system. Physical qualifications were also relaxed to make more men eligible for combat duty. Replacement depots appointed boards to review the classification of all men previously listed as limited-assignment and recommended the type of assignment for which the men were qualified.75 The first weeks of combat on the Continent were soon to reveal the inadequacy of these measures.
The Supply Plan
The build-up of U.S. forces was planned with the idea that there should be put onto the Continent the maximum force that could be administratively supported under full operational efficiency. Consequently the planned build-up of troops was inseparably related to planned flow of supplies to the far shore. The size of the force that could be built up on the Continent was limited from the beginning by the scale of logistic support which could be provided. The Allies knew that for several months after D Day more divisions would be available than could be maintained on the Continent, and one student of the problem estimated that administrative considerations would govern the rate of the build-up as late as D plus 270.76
Essentially, the problem was to gear the build-up of troops with the flow of supplies in order to insure that both daily maintenance needs and adequate reserves were provided. Maintenance requirements alone for a division slice were estimated to total approximately 900 tons per day in the early stages. Estimates of what constituted adequate reserves were altered as the invasion day approached. The Joint Administrative Plan of 19 April 1944 prescribed that an over-all reserve of 14 days of all classes of supply except ammunition and 5 units of fire of the latter be laid down in the Communications Zone for all troops by D plus 41.77 This objective was found to be unattainable, and subsequent modifications provided for a buildup of 7 days of supply of rations, 3 days of all other classes except ammunition, and
2 units of fire.78 The priorities for the build-up of these levels were in the following order: antiaircraft ammunition, Class I (rations), Class V (ammunition), and then Classes III (POL), II, and IV. An additional 7 days of supply of rations and 5 units of fire were to be built up after the foregoing priorities had been met. Supply levels in the army zones at D plus 41 were to total 7 days of all classes other than ammunition, and 7 units of fire.79
To achieve these reserve levels and at the same time meet daily maintenance requirements plus air force supply needs and various other tonnages not included in the foregoing, such as coal and civil affairs supplies, planners estimated that receipts would have to total approximately 26,500 tons per day by D plus 41, assuming a build-up of fifteen divisions and a total troop strength of about 770,000 at that date.80 At D plus 90, when there were to be twenty-one divisions on the Continent and a total troop strength of 1,334,000, they planned that theater reserves in the Communications Zone should be built up to a level of 21 days for most classes and 5 units of fire. Army levels were to be maintained throughout at 7 days of supply and 7 units of fire.81
Logistic planners at Supreme Headquarters estimated that these levels could be attained only if supplies were landed at a rate 50 percent in excess of current maintenance requirements. In other words, the build-up of the desired reserves required holding the troop build-up to a force which could currently be maintained by two thirds of the supplies landed, the balance being added to the reserve.82 Since daily maintenance requirements were expected to average about 800 tons per division slice in the D plus 41–90 period, approximately 1,200 tons of supplies per slice would have to be landed every day for maintenance and normal reserves alone. Adding various other tonnages such as coal, civil affairs supplies, boxed vehicles, pre-shipped equipment, and air force needs brought the total discharge requirement to about 45,000 tons per day at D plus 90.83
In the detailed arrangements made to meet the above requirements, particularly in the early stages of the operation, little was left to chance. Supply shipments were prescheduled for the entire first three months in order to guarantee the delivery of the minimum requirements of supplies and equipment. Daily requisitions for these predetermined needs were made for the entire ninety-day period on the basis of tonnage allocations made to the various requisitioning headquarters. Following the
OVERLORD three-phase scheme, First Army assembled all data on its requirements through D plus 14, the Advance Section (under the supervision of 1st Army Group) assembled data on the period D plus 15–41, and the Forward Echelon of Communications Zone compiled the requirements for the remainder of the ninety-day period. The assembled requisitions were sent to Headquarters, Communications Zone, the agency responsible for preparing and shipping supplies in accordance with established schedules.
One of the major problems in this planning was the allocation of shipping. It was necessary, first of all, to coordinate the available tonnage lift with the estimated day-to-day receiving capacities of the beaches and ports. The capacities of the beaches were limited, and the Navy imposed certain restrictions on the manner in which shipping was used. Further, it was necessary to allocate the lift to the major commands by supply services and classes of supply. The lift originally allocated for carrying supplies was insufficient to meet the minimum requirements of the forces at the rate of the build-up allowed by the allotted troop and vehicle-carrying craft. Shipping limitations consequently forced a reconciliation of the size of the force and rate of build-up with the maintenance capacity of the supply-carrying craft. Eventually these difficulties were overcome and a balance was arrived at between the tonnage requirements of the force, the capacities of the beaches, and the shipping allocations. Requisitions for supplies, phased by days, were then prepared on this basis and submitted to the SOS late in April and early in May.84
Most of the conditions that dictated special arrangements for the troop buildup also determined the special measures taken to insure an adequate flow of supplies to the far shore. All supply shipments in the first two weeks were to be prestowed and tactically loaded as specified by First Army. The result was a tremendous strain on depot, transportation, and port facilities, particularly the last, for cargo did not always arrive at the port in the order in which it was to be stowed, and in order to comply with stowage plans it often was necessary to hold cargo on cars in the port so that it could be loaded in accordance with discharge plans. The entire process was complicated by the necessity to assemble partial shipments from two or more depots intended for loading on one vessel. Since the holding capacity of the ports was very limited, port officials were frequently forced to depart from stowage plans.85
Headquarters, SOS, issued detailed instructions on supply movements early in May to insure that loading could be carried out in accordance with prepared stowage plans and that supplies would be moved to the ports with the shortest possible rail haul and the fewest bottlenecks. From D Day to D plus 8 (designated as the prestowed period) supplies were to be shipped in MT ships (Liberties adapted for motor transport hauling), coasters, LCTs, LCV’s,86 and barges. Coasters varying in capacity from 200 to 2,000 tons were to begin arriving on the second tide on D Day, and were to constitute the backbone of the lift in this period. One hundred and twenty-six of these vessels, carrying about 90,000 tons, were preloaded as directed by First Army, some of
them solidly with ammunition, some with engineer supplies, others with ammunition and rations. In all cases composition of the cargo was kept as simplified as possible to insure immediate access to needed items and to permit rapid sorting and distribution by the shore brigades.87 Once the supplies were unloaded the coaster fleet was estimated to have a theoretical capacity of 17,000 tons per day, but this was expected to suffer attrition from enemy action and normal marine hazards.
From D plus 9 to 21 (called the buildup phase) supply movements were to continue via MT ships and coasters, and a limited number of commodity-loaded Liberty ships were to be dispatched to the far shore. But coasters were to continue as the major carriers in this period. Complete prestowage was expected to end during this phase because of the varying capacity of ships returning from the far shore and because of the impossibility of predicting what ships would be available once the shuttle service began. Instead, tonnages would be consigned to the loading port and the stowage plan determined there by the port commander.
As handling facilities on the Continent became capable of unloading the larger ships there was to be a progressive transfer to the use of deeper-draft vessels. From D plus 22 to 41 (which the SOS referred to as the maintenance movement period) coasters were to continue to move supplies from the United Kingdom, but there would also be an increasing use of oceangoing ships, with more and more prestowed and commodity-loaded Liberties coming directly from the United States. It was also planned to commodity-load all craft leaving the United Kingdom. Finally, beginning on D plus 42 (the change-over period) ocean-going ships, largely from the United States, were to bear the main burden of the build-up, supplemented by a reduced coaster fleet from the United Kingdom.88
Scheduling supply requirements as much as three months in advance, and preloading the first two weeks’ shipments, necessarily imposed a considerable rigidity in the entire supply movement program, just as the Buildup Priority Lists did in the movement of personnel. No one could predict with complete accuracy the precise needs of the forces ashore for even a short period. Fully aware of this weakness in the supply plan, logistic planners devised several expedients to achieve a degree of flexibility in the phasing of supplies in the early stages of the operation. They also took special measures to set up emergency reserves as an insurance against interruptions in the flow of supply.
One of the expedients devised to promote flexibility was the Red Ball Express,89 a kind of “special delivery” service under which 100 tons of shipping space was set aside each day beginning on D plus 3 to meet emergency requests from the far shore. All supplies requisitioned under the Red Ball procedure were to be given top priority in packing, marking, and documentation, in movement to the port, and in handling and loading. Under another procedure, known as GREENLIGHT, 600 tons of ammunition and engineer fortification materials could be substituted on demand, depending on tactical needs, for scheduled shipments of engineer Class IV
supplies on any day. Requests for such substitutions were to allow six days for delivery. The GREENLIGHT procedure was not to become effective until D plus 14. As in the case of Red Ball, priority was to be given in the handling of all such shipments at the depot, in movement to the port, and in dispatch to the Continent.
Both Red Ball and GREENLIGHT provided a measure of flexibility in the type and quantity of supplies to be shipped to the far shore, although their purposes differed. Red Ball was established to provide for purely emergency shipments of items the need for which could not be foreseen in setting up scheduled movements. It was also a means of speedily replacing highly critical items lost in operations, items that the normal supply build-up could not deliver in time. GREENLIGHT, on the other hand, was based on the recognition that the prescheduled shipments of a very limited tonnage and type of supply might not meet tactical requirements.90
An additional degree of flexibility was provided through supply by air. Certain supplies were set up in advance for delivery on semiautomatic basis to the two airborne divisions, and parachute-packed supplies were also prestocked for emergency delivery to isolated units. In addition, as soon as continental landing fields were available, delivery of 6,000 pounds per day within forty-eight hours of request was provided for.91
Certain emergency reserves were also set up. Initially eighteen preloaded LCTs (of 140 tons capacity each) were to be beached at the tail end of the first tide on D Day. They were loaded primarily with ammunition and engineer bridging materials for which there was expected to be a demand early on D Day. Each LCT carried a truck and sufficient personnel to unload its supplies above the high-water mark. In addition, eighty-seven LBV’s92 (each with a capacity of 50 tons) were to begin arriving on D plus 1 for use in ferrying supplies from the coasters to the beach. They were preloaded with ammunition, POL, and engineer construction materials so that upon arrival they would be ready for immediate discharge without waiting for coasters to arrive. Since they were self-propelled they could be phased in as desired. Lastly, twenty 500-ton barges loaded with ammunition, POL, rations, and engineer construction materials were to be towed across the Channel within the first four days to serve as an additional bad-weather reserve. These provided a controlled floating reserve over and above planned maintenance and were to be beached and unloaded only in the event that scheduled shipments broke down.93
The above measures did not dispel all worries about the adequacy of the supply arrangements. General Moses, the G-4, was not satisfied that they would give the needed flexibility in supply movements, and he was even more concerned over the matter of building up adequate reserves on the Continent. Only a few weeks before D Day he recommended that the theater G-4 consider the establishment of machinery
paralleling the organization which was intended to control the troop buildup. However, the COMZ staff believed that an additional monitoring agency was neither desirable nor necessary. While admitting that prescheduled shipments inevitably entailed a certain degree of rigidity, it nevertheless believed that the various means of making emergency shipments and displacing scheduled shipments outlined in theater SOP’s provided the needed flexibility, and that it would be possible to cope with any special demands made by commanders on the far shore. Moreover, these procedures did not exhaust the means that could be utilized to meet serious emergencies. Virtually the entire daily supply lift, the COMZ staff argued, was available at all times for emergency loading, the only limit being the capacity of rail and truck facilities in the United Kingdom to move supplies to the ports.94
General Moses had even graver misgivings on the subject of the reserve build-up. There appeared to be no question that maintenance requirements could be met satisfactorily, at least in the first six weeks. The difficulty was that tonnage discharge was to be limited in the early phases, principally because port facilities for the reception of large ships would be lacking, and it was therefore impossible to plan for the build-up of large reserves. There was little prospect that the situation would improve after D plus 41. SHAEF planners had estimated that port capacity would reach 45,000 tons by D plus 90, but there was no assurance from the Communications Zone that it would be able to utilize it. The supply build-up, according to General Moses, was expected to be limited to 30,000 tons per day, the tonnage which the Transportation Corps estimated it would be capable of receiving and clearing from the ports and beaches. Receipts at this scale would permit no improvement in the small reserve position in the Communications Zone, and would provide no operational reserves at all for the field forces.95 In the view of the army group G-4 this limitation would create an impossible situation for the Communications Zone. While the prospect was admittedly unfavorable, the logistical planners nevertheless proceeded on the assumption that the administrative situation would be assessed in the early stages of the operation and that changes would be made in the troop build-up lists and planned cargo tonnages if necessary.
Assuming that the higher tonnage capacities could be utilized, the planners estimated that reserves would gradually start to build up so that by D plus 90 all the required reserves for the air forces would be established, and 5 units of fire and tonnages equal to about 10 days of supply in the Communications Zone would be available for all troops ashore. But even this build-up would not meet the planned levels, which called for 21 days of supply for all forces in the Communications Zone by D plus 90.
These unencouraging prospects led General Moses to state that from the G-4 point of view the logistical support of the operation after D plus 41 was precarious,
if not impossible. There were many indeterminate factors involved, of course, and, in spite of the gloomy paper prospects at the moment, no immediate changes in plan were contemplated. Hopefully, the G-4 surmised that maintenance requirement estimates might prove excessive, and reserves might be built up from the surplus maintenance brought to the Continent. Progress might also be slower than anticipated, with resulting cuts in supporting and service troops and the creation thereby of greater reserves for the troops ashore.
On the other hand, there was the possibility that conditions might be even less favorable than expected. If supplies were lost, for example, the build-up of troops might be retarded for lack of maintenance. In any event, he concluded, it was imperative that administrative developments be watched closely from the start and that the logistic potential be frequently reappraised.96
The Depot Structure
Still another aspect of the OVERLORD logistic plan which had to be given careful consideration was the Continental depot structure. Like other portions of the supply system, the network of base, intermediate, and advance depots, base maintenance shops, vehicle parks, assembly plants, and bulk POL storage facilities, was to have its rudimentary beginnings on the beaches at OMAHA and UTAH. After the landings of the assault forces the first supplies were simply to be dumped into fields immediately behind the beaches, with only a rough attempt at segregation by classes. As soon as the combat forces had expanded the beachhead sufficiently, the engineer special brigades were to bring a higher degree of order into the handling of supplies by organizing the beach maintenance areas. Service troops from each of the technical services in the First Army attached to the brigades were to supervise the establishment and operation of segregated dumps. As enough of these men became available, the installations were to be taken over and operated by army service units, the engineer brigades remaining responsible for the movement of supplies from the beaches to the army dumps. Then, as beach and port operations were developed and First Army moved forward and organized its own maintenance area, more and more installations in the base area were to be turned over to the Advance Section, which was responsible for the initial organization of the communications zone on the Continent. Eventually the Advance Section in turn would relinquish control of the coastal area as other COMZ sections arrived to take over the administration of the base area. For the first six weeks, however, the Advance Section, as the first echelon of the Communications Zone, made detailed plans for the entire administrative structure.97
Theater headquarters issued instructions in February 1944 for the establishment of depots on the Continent, and the Advance Section and Forward Echelon, Communications Zone, followed later with detailed plans specifying the exact locations of all types of installations, the amount of covered and open storage required, and the tonnage capacities of all storage facilities. Storage was planned in all the towns in the vicinity of the landing
beaches, those figuring most conspicuously being Cherbourg, Ste. Mère-Eglise, Carentan, Valognes, Trévières, La Haye-du-Puits, and St. Lô. Some of these locations were to serve as depots for two or more of the technical services, but most sites were selected for a single specific use, such as third, fourth, and fifth echelon maintenance shops, vehicle assembly plants, Class I storage, or vehicle parks. Since all sites had to be selected on the basis of map reconnaissance it was to be expected that there would be many changes once they were examined.
Planning the depot structure involved estimating the amount of space required as well as selecting the most suitable sites. Each service had to calculate its needs for covered and open storage, and, depending on its mission, for covered and open hardstandings, vehicle parks, ammunition storage along roads, and bulk POL tankage. In many cases it was important that storage be located near railway spurs and sidings.
Space requirements ran into astronomical figures. In the first six weeks alone the technical services of the Advance Section estimated they would need approximately 2,200,000 square feet of covered storage, 15,000,000 square feet of open storage, 420,000 square feet of covered hardstandings, and 2,000,000 square feet of open hardstandings. Because Ordnance listed what were probably the most varied of all the technical service requirements, its calculations serve well to illustrate the types of administrative facilities for which plans had to be made. In the first six weeks the ADSEC Ordnance Section planned to provide third, fourth, and fifth echelon maintenance for 52,500 vehicles, 2,400 weapons, and 5 antiaircraft battalions, for which it estimated space requirements at 410,000 square feet of covered and 440,000 square feet of open hardstandings. It calculated that storage of 35,000 tons of ordnance Class II supplies, plus a park for 2,000 vehicles would require 560,000 square feet of covered facilities, 360,000 square feet of open storage, and 125,000 square feet of open hardstandings. Storage space for 130,000 tons of ammunition was sited along 260 miles of road. Vehicle assembly at the rate of 100 vehicles per day was to be initiated in this period and would require 15,000 square feet of covered and a like amount of open hardstandings.98
The above figures represent the requirements only for the first six weeks, the period during which all supply installations were the responsibility of the Advance Section and all administrative installations of necessity had to be in the Normandy area. After D plus 41 there was to be a noticeable shift, with the main storage and maintenance facilities thereafter concentrated in the Rennes–Laval–Châteaubriant triangle. This shift was to coincide with the change in direction of operations from north-south to east-west as U.S. forces drove into the Brittany peninsula and at the same time east toward the Seine. Important installations were to remain in operation in the base areas, particularly at Cherbourg and St. Lô, but by D plus 90 about two thirds of all storage was to be located in Brittany and farther east.99 Plans for the depot structure, like others, however, were subject to alterations dictated by tactical needs. As events turned out they proved the least stable of all plans and were completely upset by the course of battle.
Transportation
Movements enter into virtually every aspect of supply. No other function does more to make a living organism of the logistic structure. The OVERLORD planners spent long hours on the problem of rail and motor transport on the Continent and suffered strong misgivings in the preinvasion months over the adequacy of their preparations. That the lack of transport could become a limiting factor of critical dimensions was amply demonstrated during the pursuit across northern France in the summer of 1944.
Railroads and motor transport, the latter bearing a much greater share of the burden than ever before, were to be the chief carriers on the Continent, as they had been in World War I. In the earliest stages of the operation all movements were to be carried out by truck, and very little rail mileage was expected to be placed in operation before D plus 41. As in the case of the ports, restoring transportation facilities, particularly the railways, was primarily the responsibility of one service—the Corps of Engineers—and operating them was the responsibility of another—the Transportation Corps. The latter had been created as recently as 1942, taking over the operation of motor transport from the Quartermaster Corps and of railways from the Corps of Engineers.
The Corps of Engineers began planning the road repair and highway bridging requirements for OVERLORD almost two years before the invasion. For this purpose it established working figures on the capacities of roads of particular widths, made assumptions on the degree of destruction that could be expected, and estimated the amount of construction materials and number of repair units required. Some of these figures were obtainable from experience in the Mediterranean theater, some were secured from tests in the United Kingdom. The Allies did not have full information on the condition of roads in the lodgment area. France had a traditionally fine road network, however, and main roads were hard surfaced and suitable for year-round traffic. The principal restriction to the easy flow of traffic was expected to come in the bottlenecks created by the narrow streets of the older towns. In the early stages of the operation the limited size of the lodgment would undoubtedly present difficulties, particularly at the base of the Cotentin, where egress from the peninsula was limited to a few causeway-type highways across the low, swampy Douve valley.100
Enemy-inflicted damage to highways was not expected to be great. Most of the early repair and reconstruction would undoubtedly be required on bridges, and First Army engineers would have to do these initial jobs. As areas were released by the army, the Advance Section would assume responsibility for the continued repair and maintenance of roads. One engineer general service regiment was believed capable of reconstructing 10 to 12 miles of road per day and properly maintaining about 170 miles. To meet estimated needs in the first six weeks, five general service regiments and two dump truck companies were to be assigned to road maintenance and repair for that period. Additional plans were drawn by another COMZ section for the repair and maintenance of the Brittany roads.101
The mission of the Transportation
Corps with respect to the operation of motor transport was to carry out all motor transportation connected with port clearance, static inter-depot operations, and line-of-communications hauling. This entailed traffic regulation, both at the ports and along the lines of communications, and the establishment of regulating stations to control movement into the army areas. For several months after the invasion the Transportation Corps was handicapped by the lack of a centrally controlled motor transport service, although the Advance Section organized a provisional motor transport brigade to provide centralized field control over its own transportation shortly before D Day. Most of the theater’s truck companies had actually been activated as Quartermaster units, and many continued to carry the designation “QM Truck Company (TC)” for some months.
To accomplish its motor transport mission the Transportation Corps estimated that, in addition to the vehicles furnished the field forces, 240 truck companies would be needed in the Communications Zone, and that two drivers should be provided each vehicle to permit round-the-clock operation. It also requested that a large percentage of the truck units be equipped with the large 10-ton flat-bed semitrailers and truck-tractors. Just before D Day theater headquarters granted the additional drivers, but it had authorized only 160 truck companies for the operation, and only a small percentage of the larger capacity truck-tractor-semitrailer units could be furnished. The smaller 2½-ton 6 x 6 truck had to be substituted. Plans called for moving 130 companies to the Continent by D plus 41. This number of units was expected to meet the daily forward movement requirement of 23,700 tons at that date.102 But there was serious apprehension in several quarters over the adequacy of motor transportation after the first six weeks. Logistical planners at SHAEF noted that the shortage of truck companies was one of the chief factors likely to limit the development of the lines of communications even if operations proceeded as planned,103 and it was this shortage which led General Moses to express misgivings over the prospects of adequately supporting operations after D plus 41.
Important as motor transportation was to be in operation OVERLORD, it was not expected to sustain the mounting volume of supply movements after the first few weeks. From the beginning the Allies counted on the railways—a far more economical carrier over long distances—eventually to bear the larger portion of the transportation burden. Restoration of the French rail lines took on added importance in view of the anticipated shortage of truck transport.
Lack of a final operational plan made it impossible for a long time to prepare accurate estimates of matériel requirements. Nevertheless, requisitions for special Class IV equipment had to be placed far enough in advance to insure procurement and delivery in time for the operation. Supply planners found it necessary therefore to estimate needs on the basis of hypothetical operational plans, assuming a rail line of communications of a certain length and assuming certain scales of destruction.
In the meantime studies were made to
Map 9: OVERLORD Rail and Pipeline Plans
determine the exact condition of the French railway net. The lack of intelligence on European rail lines handicapped planning at first. This was remedied when the British turned over to ETOUSA engineers considerable information on the French railways.104 Engineer studies covered such matters as the state of track maintenance, grades, carrying capacity, number, type, and size of bridges, the kind of water and coal facilities, and the size of yards. Estimates of damage to the rail system were considerably higher than for highways. For planning purposes it was assumed that 75 percent of the track and all bridges would be destroyed. A portion of this trackage and bridging was expected to be salvageable, but reconstruction of the lines was estimated to require 55 percent new ties and rail and 90 percent new bridging. These estimates were based on the enemy’s performance in the Mediterranean theater, where demolitions had been extensive. In Italy the Germans had employed a tie-breaking machine which systematically tore ties from the roadbed and automatically dropped a charge which broke the rails at regular intervals.105
ADSEC engineers made all the detailed plans for railway reconstruction as far south as Rennes, although this involved projects which were expected to require almost three months to complete. (Map 9) First priority was given to the reconstruction of the yards at Cherbourg. Port clearance facilities were of first importance, and rail operations were logically based on Cherbourg as a starting point, for that port was the only suitable point of entry for locomotives and rolling
stock, and the only port capable of handling awkward equipment. Rail line restoration was to be completed only as far as Lison Junction, a few miles southeast of Isigny, by D plus 41. By D plus 90 a total of only 245 miles was scheduled to be in operation, consisting mainly of a trunk line along the route Cherbourg–Lison Junction–Folligny–Dol–Rennes.106
The rail plan thus fitted into the general logistic scheme to develop the lines of communications southward to the Rennes depot area, but it was a modest one considering the size of the OVERLORD lodgment area and the eventual course of operations. ADSEC engineers developed plans to reconstruct roadbeds, culverts, and bridges, reclaim salvageable track materials, relay tracks, install yards and sidings, and rehabilitate or construct water and coal supply facilities. With characteristic thoroughness the Corps of Engineers made detailed studies of the work involved in the repair of each bridge, culvert, arid spur, and prepared bills of materials listing every need from rock crushers and concrete mixers to ties and spikes. In the 47-mile stretch from Cherbourg to Lison Junction alone the plan listed eighty bridges which might require rebuilding. It was estimated that 47,500 tons of construction material would be needed for the reconstruction of the mileage outlined above. This included steel bridging and culverts, track materials, and miscellaneous items such as cement, lumber, and piling, all phased to arrive at certain ports or beaches in specific amounts, within daily tonnage allocations.107
The troop units provided for this mission totaled five engineer general service regiments, three engineer dump truck companies, and one engineer heavy ponton battalion. Although a training program was worked out for the engineer general service regiments assigned to this work, they had very little experience in railway reconstruction before the invasion. Two of the regiments—the 332nd and 347th—had attended the joint U.S.-British railroad bridging school in the United Kingdom. They were the only units that received any measure of specialized training for their continental mission.108
In all the planning for reconstruction of the continental railways, the engineers maintained close liaison with the Transportation Corps, which organized the 2nd Military Railway Service to operate the lines. The 2nd MRS was commanded by Brig. Gen. Clarence L. Burpee, who had come into the service from the Atlantic Coast Line. In the early stages of the operation the Railway Service was to be limited primarily to reconnaissance of captured rail lines, and the Corps of Engineers was to determine what alterations in plans, if any, should be made in restoration of lines. To operate the lines the 2nd Military Railway Service organized railway grand divisions, intended to handle roughly the area of a base section. A grand division was normally capable of operating from 250 to 450 miles of railway, depending on the number of units assigned to it. For early operations, to D plus 41, the Transportation Corps provided one railway grand division, with two railway shop battalions and two railway operating battalions.109 Not until after this period, however, would operation of the lines become extensive.
The Supply of POL
The magnitude and importance of the movement problem are nowhere better illustrated than in the separate plans which were made for the transportation of petroleum products. Arrangements for POL supply enjoyed a preeminence in the planning and preparation for OVERLORD matched only by the plans for port reconstruction. POL alone accounted for one quarter of all the tonnage transported to the European Theater of Operations—a convincing statistical token that gasoline had become the lifeblood of modern armies.
The extraordinary demands for POL which the cross-Channel operation was expected to make called for extraordinary preparations. From the very start of invasion planning provision for adequate POL supply focused on the use of some kind of a light pipeline which could be laid down quickly so that gasoline could be transported economically over long distances. British experimentation with this idea began shortly after Dunkerque, and the production of such a pipeline figured in the early ROUNDUP planning. American interest was quickened by the appointment of a special Petroleum Committee in the United Kingdom to study the problem in July 1942, shortly after the European theater was activated. At about the same time the Chief of Engineers in Washington outlined a POL distribution plan which provided for lightweight pipelines which could be laid at the rate of twenty or more miles per day.110
Planning for continental POL supply thus got under way at an early date, although definitive plans were long in taking shape. Attempts to requisition materials for a POL distribution system were initially frustrated by the TORCH operation. Experimentation continued, however, not only with an overland pipeline, but with submarine pipelines and ship-to-shore lines. POL planners had much to learn about the handling of equipment and the training and organization of personnel. They attempted to establish sound bases for estimating the POL needs for a continental operation, and found it necessary to requisition enormous amounts of special equipment. Their efforts were partially negated by the lack of a firm troop basis and by the lack of figures on the ratios of vehicles to troops. Nevertheless the later OVERLORD planners profited by the plans and experimentation of the ROUNDUP period. For want of adequate experiential data, the POL planners initially placed considerable reliance on British estimates, particularly for requirements. Estimates as to the earliest date on which POL could be supplied in bulk to the Continent were pessimistic at first. Because all shipping was preoccupied with the movement of supplies and equipment essential to combat operations in the early stages, there was little hope that bulk supply could be initiated before D plus 30.
Planning a POL distribution system also posed an administrative problem since there were several interested parties or services. POL was a quartermaster item of supply. But any system entailing construction of bulk facilities and pipelines involved the engineers. Transportation of POL products, whether by tanker, railway tank cars, or tank trucks, was the job of the Transportation Corps. Ordnance was involved as the designer and supplier of much of the equipment such as
vehicle-loading pumps and hose. The air forces were interested as the consumer of aviation gasoline, for which special provision had to be made. Coordinating the interests and responsibilities of these various parties was a difficult task in view of the initial lack of a single agency for that purpose.
POL plans began to assume a clearer outline late in 1943. COSSAC plans at that time called for an intake installation at Port-en-Bessin to receive POL in bulk from tankers in the harbor and via ship-to-shore lines, for storage facilities farther inland, and for a single 4-inch pipeline to St. Lô and Coutances. Contrary to earlier conclusions concerning the availability of tanker shipping for the transport of bulk POL, the COSSAC plans now called for work to begin on bulk installations as early as D plus 5. The initial receiving and storage installations were scheduled to be completed by D plus 10, and the entire line was to be completed by D plus 20. The possibilities of meeting such a schedule were viewed with considerable pessimism until the achievements in the Sicilian operation became known.
The Port-en-Bessin installations and inland pipeline were only part of the POL plan developed by the COSSAC planners in 1943. A similar bulk receiving system was contemplated at Cherbourg, and two pipelines were to reach south from Cherbourg along the axis La Haye-du-Puits–Avranches–Laval. They were to be supplemented by additional lines from the Brittany ports inland to Laval. Construction of this system was scheduled to begin immediately after the capture of Cherbourg and was to be completed by D plus 90.
Preparing to implement these plans was another matter. Until the end of the year there was no definite basis for figuring the requirements of motor or aviation fuel, which was a prerequisite for sound planning by the Quartermaster Corps and the Corps of Engineers. There was continued lack of coordination between the services, and there were not enough men trained for this type of operation. Before adequate planning data were agreed on, confusion, disagreement, overlap of authority, and loss of time attended plans for the establishment of POL sections in the various services and echelons of command.
The lack of an agency at the general staff level which could settle jurisdictional differences and coordinate the responsibilities and interests of the several services involved in POL supply was finally remedied in February 1944, when a POL Branch was established within the G-4 Section, ETOUSA, under Col. Freeman W. Burford. In the next two months a concerted effort was made to arrive at definitive data on requirements so that lower echelons could write detailed plans. In this planning technical advice was furnished mainly by officers who had served with the big oil companies such as Standard, Shell, and Humble.111 By the end of March the estimated pipeline and storage tank requirements were established for OVERLORD. They provided for a considerably higher estimate of POL consumption rate, a larger proportion of reserves to be held in bulk storage, and a more extensive coverage of the operational area with bulk distribution lines than originally anticipated. The revised estimates were immediately reflected in higher matériel requirements and made the whole problem of supply of construction equipment
a critical one. Much additional equipment, particularly 6-inch pipe, had to be requisitioned. The fact that much of it had to be obtained from British sources meant some sacrifice of standardization.
In the meantime the delivery of construction materials already on order through PROCO requisition was disappointingly slow, and alarming shortages developed as D Day drew nearer. One of the missions of General Moore, chief engineer of the theater, on his trip to the United States in March 1944 was to impress upon the Procurement Section of the Office of the Chief of Engineers the urgency of filling requisitions promptly. In the last months before the invasion there were times when it was very questionable whether enough materials would be available by D Day to carry on the contemplated construction in the first weeks on the Continent. Even the training program for engineer petroleum distribution units suffered from such deficiencies. Shortly before D Day high priorities were given to the shipment of the most urgently needed materials. A survey of the stock status of POL equipment in May revealed that with certain exceptions all items listed as critical by the Advance Section could be supplied for the period up to D plus 14, and it was believed that new stocks arriving in depots would be sufficient to meet requirements from D plus 15 to D plus 41. By 1 June preparations for the POL plan were adequate to meet all the needs of the operation.
Problems had also arisen in connection with the proper handling of the materials on hand. Removal of packing lists from boxes often made it difficult to determine the contents of individual crates. POL equipment was scattered over a large area rather than concentrated in one depot; and troops were placed in the depots who were unfamiliar with the nomenclature of items and could not identify articles of equipment. Worse still was the poor care given some of the equipment. Items such as elbows, tees, and valves often lay in the open or were stored in uncovered barrels which collected rain water. Some of these abuses and deficiencies had been noted on inspections in 1943, and corrective measures were taken.
The final U.S. plans for a POL distribution system on the Continent were based on a plan issued by the POL Branch, G-4, ETOUSA, on 14 April 1944. Participating in this planning were representatives from the Quartermaster Corps, the Transportation Corps, the Air Forces, and the Corps of Engineers. The Advance Section, in turn, used this outline as the basis of its more detailed plan, which set forth the organization and operation of the major portion of the pipeline system in the first six weeks of the operation. Of the various ADSEC technical service annexes, by far the most detailed plan was written by the Corps of Engineers, even though POL was a quartermaster supply item and the Quartermaster Corps had the responsibility of receiving, storing, and issuing all packaged POL products at Class III supply points and performing all decanting of POL from bulk to packages. The Transportation Corps had a large measure of responsibility in transporting POL, first in tankers and finally at the opposite end of the supply line in cans and in tank trucks. But it was the Corps of Engineers which had the most extensive mission. The engineers not only had to construct all bulk POL facilities, but they had to operate them—a task that entailed the reception, transportation, and storage of the great bulk of
all POL products needed by U.S. forces.112 The final POL distribution plans were based on estimated maintenance needs plus certain reserves. Maintenance requirements were based on an assumed rate of consumption for various vehicles per operational day. First Army assumed a 25-mile operational day for the first two weeks and a 50-mile operational day thereafter. Consumption per 50-mile day was taken as 8 gallons per wheeled vehicle, 24 gallons per half-track, and 52 per full track. Beyond this certain allowances were made to provide for powered equipment. Using these basic working figures, and the number of vehicles scheduled to be phased into the Continent, planners estimated that the following daily tonnages of POL products would be required at D plus 14, D plus 41, and D plus 90:113
| Date | Total | MT 80 | Avgas | Diesel | Kerosene | Lubricants |
| D + 14 | 5,084 | 4,470 | 398 | 873 | 11 | 250 |
| D + 41 | 7,350 | 4,663 | 1,076 | 1,226 | 64 | 321 |
| D + 90 | 7,145 | 4,477 | 1,059 | 1,182 | 67 | 360 |
These requirements assumed a strength of approximately 67,000 vehicles on the Continent on D plus 14, 183,000 on D plus 41, and 263,590 on D plus 90. To meet their goal, the Allies had to introduce a total of 271,158 tons of POL products in the first 42 days. This included the aviation gasoline (Avgas) requirement, but the bulk of the tonnage (183,233 tons) was allocated to motor vehicle (MT80) gasoline. These amounts would provide a required reserve level of 7 days on D plus 14, 14 days on D plus 41, and 21 days on D plus 90.
For the first twenty-one days of the OVERLORD operation all POL needs were to be shipped packaged—that is, in cans. Bulk deliveries were scheduled to begin on D plus 15, although a small percentage of MT80 shipments was to continue in packages in order to build up and maintain the can population on the Continent.
The entire POL plan for Operation OVERLORD centered on the two big pipeline systems, designated as the Major and Minor Systems. (See Map 9.) The Minor System, scheduled to be constructed first, included facilities for receiving, storing, and dispensing bulk POL products in the Port-en-Bessin–Ste. Honorine-des-Pertes–Balleroy area. It was to consist of tanker berthing facilities and unloading lines, onshore booster stations, inland tank farms (for storage), pipelines, pumping stations, and dispensing facilities. Tanker deliveries were to be discharged through two receiving points. British and American forces jointly were to use Port-en-Bessin, a British-controlled port with berthing facilities, as a discharge point for tankers carrying both motor vehicle and aviation gasoline. Discharge was to be through two 6-inch lines, delivering both to the British and, through booster pumps, to the U.S. tank farm at Mt. Cauvin (near Etreham), about two miles distant from the port. Ste. Honorine-des-Pertes, two miles to the west and convenient to suitable offshore anchorage, was to be the other receiving point, used for the receipt
of motor vehicle and diesel fuel for U.S. Army and Navy use. Discharge at that point was to be effected via two 6-inch ship-to-shore submarine lines (called TOMBOLAS), and delivery was to be made to the Ste. Honorine storage system, and by pipeline to the Navy fueling station at the site of the MULBERRY. The Ste. Honorine storage capacity was to total 20,000 barrels, the Mt. Cauvin tank farm 24,000 barrels. This much of the Minor System was to be completed and in operation by D plus 10. Within the next six days pipelines were to tie in the Ste. Honorine storage system with the lines at Mt. Cauvin, and from this point a 4-inch line was to be constructed to Balleroy, about thirteen miles to the south. Terminal storage tanks with a capacity of 6,000 barrels were to be erected at Balleroy, which, like Mt. Cauvin and Ste. Honorine, was to have dispensing facilities both for canning and for loading tank trucks. The entire project involved the construction of twenty-seven miles of pipeline with the necessary booster stations and fittings, and tank storage, for 54,000 barrels. Since there were no known commercial facilities in the area the entire system was to be newly constructed.114
While the Minor System was designed to meet the Allies’ needs for bulk POL in the initial stages of operation OVERLORD, the biggest share of bulk POL deliveries was eventually expected to be made through the larger and more permanent system based on Cherbourg, known as the Major System. This, like the Minor, was to consist of discharge points, storage facilities, and pipelines, but it was conceived and planned on a much larger scale and, when completed, was to have many times the capacity of the earlier development east of OMAHA Beach. The outstanding features of the Major System were the large discharge capacities at Cherbourg, the long pipelines, and the enormous storage capacities to be developed along the pipeline route.
Deliveries at Cherbourg were to be made principally via tanker discharge alongside the Digue de Querqueville. Five 6-inch lines were planned to handle these deliveries. In addition, one 6-inch line was to receive fuel directly from cross-Channel submarine lines. The latter project was an even more novel feature of the invasion operation than the MULBERRIES. The Allies had seriously considered the idea of submarine pipelines throughout the planning period, and after extensive experimentation the British developed cables that could be laid underwater and would carry POL under high pressures. The Corps of Engineers also conducted experiments in the United States, but this project was abandoned in December 1943 because it could not be completed in time to justify the enormous expenditure of effort that was required.115 The cross-Channel underwater pipeline plan which was adopted was therefore exclusively a British project. Known as PLUTO (for pipeline under the ocean), it provided for the laying of ten 3-inch cables from the Isle of Wight to Cherbourg, the first line to arrive on D plus 12.116 At a distance of sixty miles each line had a theoretic delivery capacity of over 300 tons of gasoline per day. Because PLUTO was substantially an untried project until after it started
actual operation, all POL planners considered deliveries via the submarine supply line as a bonus, over and above the total requirements which, for planning purposes, were to be delivered by the more orthodox tanker method.117
To carry bulk fuel inland plans were made for the construction of three 6-inch pipelines from the Digue de Querqueville in Cherbourg south to Laval and then eastward to the vicinity of Etampes, south of Paris. In addition, tactical conditions permitting, it was hoped that other lines could be built from the Brittany ports, either from Vannes (in the vicinity of Quiberon Bay) to Châteaubriant, running northeastward to join the Major System at Laval, or preferably a supplementary line starting at Donges at the mouth of the Loire, and running eastward through Angers, Tours, and Orléans.118 The Advance Section, as the command responsible for detailed plans through D plus 41, made definite plans to extend the lines only to the Brittany area, where the big depots were to be established. Two of these lines were to carry motor vehicle fuel and the third was to carry aviation gasoline. The three lines were to be laid side by side as far as Fougères, a distance of 101 miles. From Fougères a 4-inch branch line (for MT80) was to be extended to Rennes (28 miles) for local distribution. From Fougères southeast two 6-inch lines were to continue to Laval (also 28 miles from Fougères). In addition, by D plus 41 a branch line was to have been started from Laval southwest to Châteaubriant, partially for the purpose of connecting with lines from the Loire River ports.
The three 6-inch lines from Cherbourg were to constitute the major pipeline system running to the south and east, and were to carry the major portion of bulk POL projects to U.S. forces. The 6-inch lines had a rated capacity of 1,825 tons per day, and the 4-inch lines a capacity of 825 tons. For planning purposes, however, factors of 1,515 and 650 tons respectively were used.
Another vital feature of the Major System was the storage plan. In writing the POL plan for operation OVERLORD the planners did not lack intelligence on the existing facilities in the Cherbourg and Brittany peninsulas. They knew, for example, that Cherbourg had extensive tankage capacity, since it had been a naval base; but, as in the case of the ports, they assumed that such facilities would be destroyed.119 They therefore planned a tremendous storage program, particularly at Cherbourg, where thirty-eight tanks were scheduled, most of them of 10,000-barrel capacity, with a total capacity of 331,000 barrels. They were to be built on the high ground southwest of Querqueville, concealed and dispersed, but so interconnected as to permit complete flexibility of operation. In order to provide the inland reserve storage, both for local dispensing when pipelines were shut down and for operational storage, tanks were to be built all along the route of the pipelines, at La Haye-du-Puits, Coutances, Avranches, Fouèkres, Rennes, and Laval, all within the first forty-two days. By D plus 46, when the Craon and Châteaubriant additions were to be completed, a total of eighty-three tanks would have been constructed, with a capacity of 536,000 barrels.120 As part of these plans, dispensing facilities were to be provided at
every storage area, consisting of both truck-filling and canning facilities.
The construction of the Major System followed a schedule, as did all construction projects in the OVERLORD operation. By D plus 21 storage and pipeline construction was to have progressed sufficiently to permit dispensing and storage to begin at La Haye-du-Puits. By D plus 26 a single pipeline was to extend as far as Coutances, and by D plus 31 to Avranches, with storage and dispensing facilities. Meanwhile, work was also to proceed on the second and third pipelines and on storage facilities, so that by D plus 41 the system was to have been completed and in operation as far as Rennes and Laval. A total of 513 miles of pipeline was to be laid in the Major System up to this point. Adding the facilities of the Minor System in the Port-en-Bessin and Balleroy area (27 miles of pipe and 50,000 barrels of storage) a total of 540 miles of pipeline and 586,000 barrels of storage capacity was to be completed and in operation by D plus 46.121
Modest as was the Minor System as compared with the one based on Cherbourg, it assumed enhanced importance as D Day drew near. Mention has been made of the change in tactical plans made only a week before D Day when assault units were already marshaling for the cross-Channel movement. This change not only affected the plans for the phasing in of combat and service units but also caused a revision in the estimated capture date of Cherbourg, setting it back one week to D plus 15. It therefore had a special significance for the supply of POL. The POL plan relied heavily on the capture of Cherbourg and the early construction of receiving and dispensing facilities there so that the scheduled transfer from packaged maintenance to bulk maintenance could be made by D plus 21. Any delay in the capture of Cherbourg set the POL plan back proportionately. A week’s delay would cause a shortage of 31,400 tons of estimated maintenance and reserve requirements.122
To make up this deficit either additional quantities of packaged POL would have to be introduced to offset the delay in bulk deliveries, or additional bulk-receiving facilities would have to be provided. After discussing several possibilities G-4 officials decided on 29 May that the best solution was to increase the bulk capacity of the Minor System. Meeting maintenance requirements with packaged POL would have required adjustments of the whole supply phasing program. They decided rather to increase both the receiving and storage capacity in the Port-en-Bessin–Ste. Honorine–Balleroy area, and made a special allocation of shipping to bring an additional 700 tons of POL construction materials over the beaches for this purpose at an early date.123
The vital importance of the OVERLORD POL plans is reflected in the meticulous detail in which they were written. They resembled the port plans in the multitude of considerations that the planners had to take into account. Certain basic assumptions had to be made, including the average mileage of an operational day, the
rate of consumption for each type of vehicle, and an estimated rate of advance. To arrive at estimates of total requirements the planners had to know both the troop and vehicle population on the Continent at different stages. Beyond this fundamental information the ability to construct an adequate POL distribution system on the Continent depended on both the supplies and equipment and the specially trained units which were to be available for such a project. A mass of technical data had to be gathered and applied. The computation of pipeline construction alone involved consideration of all the problems of surveying, clearing the right of way, stringing pipe, connecting joints, installing pump stations, testing and filling the pipeline, building a communications system, and erecting and connecting storage.
Assuming that the construction work was completed, the planners still faced a formidable array of computations and calculations. What, they had to estimate, was the capacity of QM units to decant and to distribute? What was the capacity of TC trucking companies to transport? To answer the latter question they had to determine what types of transportation and container—can, drum, tank truck, skid tanks on cargo trucks, or 2,000-gallon trailer trucks—were best suited to various areas in various stages of the operation. How much should they allow for delays from traffic blocks and breakdowns, for interruptions in loading and unloading, for difficulties in locating dumps? What should be the ratios of motor vehicle, aviation, and diesel fuel, of kerosene, and of lubricants; what percentages of reserves should be maintained in package and bulk at various times; what would the turnaround time be; what losses of containers should be expected in maintaining an adequate can population? Such matters as draft, port rehabilitation, turn-round time, and loading time entered into the planners’ consideration of what type of tankers should be used. To coordinate all the facts and the informed guesses and to synchronize the plans of the various services were tasks of almost infinite complexity. They were tasks, however, on which the success of the invasion depended.
The very bulk and detail of the OVERLORD logistic plans indicate that the planners were determined that every need should be anticipated, and that no requirement, down to the proverbial nail, should be wanting. The logistic plan was based on a deliberately optimistic forecast of tactical progress to insure a timely build-up of troops and supplies, and to insure that the combat forces should never suffer from want of adequate logistic support. On the other hand, operational plans, including the rate of the troop build-up, were so drawn as to utilize the full potential of the supply organization. The entire plan, therefore, represented an attempt to balance requirements with capabilities.
Whether the logistic structure would prove sufficiently flexible to accommodate itself to changing conditions, and whether the capacities of the various facilities along the supply pipeline could be balanced so that strictures did not develop, remained to be seen. The repercussions which late intelligence concerning enemy strength in the Cotentin could have on both tactical and logistic plans had already demonstrated the need for resilience in the supply organization. Logistic planners had long been haunted by the specter of “limiting factors” which might choke the lines of communications at one point
or another. The smooth flow of supply required that all parts of the system operate approximately according to rated capacity. The limiting factor at one time might be a shortage of shipping, at another the capacities of the French beaches and ports. In trying to anticipate the limiting factors the planners had been handicapped initially by the fact that all branches of the staffs started planning at the same time, and decisions were taken before reliable statistical data were available or the limiting factors determined. In mid-April the limiting factors which logistic planners appeared most concerned about were the transportation facilities on the Continent, in which the chief deficiencies were expected to be the shortage of truck companies, the limited capacity of the road net in the early stages, and the slow rate of rail reconstruction. These deficiencies, it was thought, might well limit the scale of operations after D plus 90.124
The SHAEF G-4 found little reason for complacency regarding the prospects for even the first three months. In an eleventh-hour assessment of the logistic preparations for OVERLORD he concluded that the operation would be logistically feasible only if certain conditions were met: the front line at D plus 90 must not be any farther advanced than the planned line of the Seine-Loire; the build-up must be limited to troops absolutely essential to the operation; the Allies must be able to maintain a considerable portion of reserves in the vicinity of the ports, and full operational reserves must not necessarily be kept in the most advanced depots; a rail net must be developed as planned with adequate rolling stock. There was a distinct possibility, the G-4 surmised, that some factors, such as port capacity or the extent of rail damage, might be less favorable than assumed. The failure of only one important function—port clearance, for example—might create a bottleneck which could alter the entire course of the operation. In essence, the G-4 study seemed to say that the operation could be supported provided everything proceeded as planned, and that there was no margin of safety in the logistical arrangements for OVERLORD.125