Chapter XV: The Final Months of the War
During the last months of the war, the Allied forces made great strides both in driving toward the Japanese home islands and in liquidating the Japanese conquests made earlier in the war. The destruction of organized resistance in the Philippines and Borneo all but severed the Japanese lines of communication to the East Indies and southeast Asia, while the capture of the islands of Iwo Jima and Okinawa, so close to Japan itself, put the Empire in gravest danger. In southern China, the Japanese forces, which had advanced threateningly in 1944, were, by the spring of 1945, in full retreat. While enemy forces were being destroyed or were in retreat on the islands of the Pacific and on the Asian mainland, the more remote bases were being dismantled and closed out, but an enormous amount of base and airfield construction was still under way, particularly in the Philippines and on Okinawa, for the purpose of supporting an invasion of Japan proper. At the same time, plans and preparations were being made for the invasion itself.
Destruction of the Japanese in the Philippines and Borneo
Overall Plans
Since the Philippines, particularly Luzon, were to constitute the most important base area to support the coming invasion of Japan, the enemy forces on those islands had to be destroyed or rendered harmless. No time was lost in getting on with the job. While Manila and Corregidor were still under attack, operations were begun against the Japanese who had withdrawn into the outlying parts of Luzon as well as against those still more or less in control of the central and southern islands of the archipelago. On 5 February 1945 MacArthur directed Sixth Army to destroy the Japanese in northern, eastern, and southern Luzon. The next day, he directed Eighth Army to seize certain islands in the central and southern Philippines.
Sixth Army’s plan of campaign on Luzon called for the destruction of the enemy by three corps. I Corps would have the mission of capturing Baguio and securing the Cagayan Valley, with the city of Aparri, on Luzon’s northern coast. XIV Corps was to begin the task of destroying the Japanese in the Sierra Madre mountains of east central Luzon. After the first few weeks, XI Corps was to take over this mission, while XIV Corps attacked the Japanese in the southern and southeastern parts of the island. Eighth Army’s operations in the central and southern Philippines, to be known as the VICTOR operations, were to be amphibious assaults. The first would
be directed against the southwestern islands—Palawan, the Zamboanga peninsula of Mindanao, and the Sulu Archipelago. Thereafter, four of the major islands in the central Philippines—Panay, Negros, Cebu, and Bohol—were to come under attack. These four were part of the Visayan group of islands, two of which—Leyte and Samar—were already under American control. Lastly, the Japanese in the main part of Mindanao would be crushed. Thereupon, the Philippines would be completely under American control.1
Engineer Planning
Sixth and Eighth Army engineers began planning after receiving MacArthur’s directives. Sturgis’ engineer section made a study of the terrain of the more remote parts of Luzon and the highways and trails leading to them. Unlike the amphibious operations along the New Guinea coast or the advance down the Central Plains, the drives into the outlying parts of the island would be, for the most part, through mountainous terrain. After making extensive reconnaissances from the air and on the ground, Sixth Army engineers were convinced that their most important task was the construction and maintenance of roads. Bridging would probably not be a major job until the onset of the rains in May. Japanese mine fields and demolitions would very likely be as crude as before, but in the mountainous parts of the island might be considerably more effective in holding up an advance. Engineer work, unlike that performed in New Guinea, would, as a rule, be done in the conventional manner. Troops under corps and army would undertake major construction in back of and not at the front lines. Since there were not enough engineer units or supplies to support three simultaneous actions in widely separated areas, General Sturgis decided to keep most of his heavy construction troops under army control in or near Manila until developments showed where they could be used to best advantage.2
Meanwhile, Eighth Army engineers under Col. David M. Dunne were deep in plans and preparations for the VICTOR operations, of which there were to be five. The various islands of the central and southern Philippines had similar terrain—a narrow coastal belt behind which rose steep and wooded mountains. There was little time for reconnaissance, and map coverage was inadequate. Since the attacks were to be amphibious, they would undoubtedly be carried on in the same manner as the earlier similar operations along the New Guinea coast. Heavy naval and air bombardments would drive the enemy away from the beaches and into the interior of the islands so that, soon after the initial landings, the engineers could begin work on bases and airfields virtually unhampered. The Eighth Army engineers, in making tentative plans for construction in each area, had to devote considerable effort to getting sufficient numbers of troops and adequate amounts of supplies. The relatively few units
available were so apportioned that each operation would have amphibian and combat units and either aviation or construction battalions.3
East Central Luzon
On Luzon the first attack began on 20 February when the st Cavalry Division and the 6th Infantry Division of XIV Corps launched an assault against the Japanese who had retreated into the Sierra Madre Mountains in the east Central part of the island. In this rugged and inhospitable region, where roads were few, the terrain greatly favored the defenders. Here the Japanese had under their control Ipo Dam, and ten miles to the southwest, Montalban Dam, two important elements of Manila’s water supply system which had to be captured intact, if possible. The engineers were in continual demand to support the infantry in the drive through the mountains. Tasks of the 8th Engineer Squadron and the 6th Combat Battalion were similar. Mines were numerous along the narrow and primitive roads. In many places, the Japanese had set up roadblocks and covered them with fire. Some were of the abatis type; others were blasted out of the steep slopes on both sides of the road or path. Engineer demolition teams helped destroy caves, bunkers, and pillboxes in which the enemy were hiding. A major task was building and maintaining roads. Often the infantry had to wait until the engineers could fashion a trail. Steep grades, large outcroppings of rock, and enemy fire all slowed down construction. Maintenance of the roads, most of them unsurfaced and rough, was complicated by the constant traffic.4
Northern Luzon
The attack against the Japanese on northern Luzon began on 21 February. By that date, I Corps held a line across the narrow waist of the island from Damortis on Lingayen Gulf in the west to Baler Bay in the east. The Cagayan Valley, a major food-producing area, stretched more than 200 miles to Aparri. Bounded on the east, west, and south by broad and rugged mountain ranges, it had two approaches from the south feasible for military operations: one from Bambang; the other from Baguio, fifty miles to the west. Bambang could be reached by two routes. One was by way of Highway 5 running from San Jose, at the edge of the Central Plains, up the Tulavera River valley to Balete Pass. The enemy positions at the pass were considered the key to the southern defenses of the Cagayan Valley. Once they were taken, the forward movement down the valley would be relatively easy. Another possible route was by way of the Villa Verde Trail, a path for foot travelers and carabao, which began to twist through the mountains 25 miles west of Highway 5 and joined it just north of Balete Pass. Baguio had four approaches. Highway 11, also known as the Kennon Road, was the most direct. From Rosario it ran northeast and then north through the Cordillera Central
Mountains. A longer route was by way of coastal Highway 3 and then inland by way of Highway 9. Two trails to Baguio cut through the rough triangle formed by the three roads. From Baguio, dirt roads and trails led eastward through the Cordilleras to the Cagayan Valley. The 25th and 32nd Infantry Divisions were to take Bambang; the 33rd Infantry Division was to capture Baguio and then assist the other two in the drive up the Cagayan Valley. Progress of the drives through the mountainous terrain of northern Luzon would depend in large measure on the success of the engineers in overcoming natural and man-made obstacles.5
The Advance to Barn bang
The 25th Division, with its 65th Combat Battalion, moving north from San Jose along Highway 5, got off to a good start. By mid-March, that is, in about three weeks, it was nearing Balete Pass. The engineers kept pace with the infantry, developing the highway, a two-lane graveled road, as the main supply route for the division. Most of the men were engaged in repairing and reinforcing bridges. They cleared three mine fields and spent much time probing for additional mines which the enemy had scattered about in haphazard fashion. Just to the south of Balete Pass, the road ran through a deep defile. The nearer the troops approached the pass, the greater became the enemy’s resistance. Since a frontal attack would be costly, the engineers had to put in numerous side roads through the rocky terrain to make possible flank attacks on enemy positions. Because the roads would be abandoned after the troops had won the area, bridges were not put in; the engineers either found fords or constructed temporary crossings of steel culverts. The men had to be continually on the alert for mines. It was standard practice for the enemy to sneak back and replant an area previously cleared.6
The Villa Verde Trail
When the 25th Division began its drive toward Bambang, the 32nd Division with its 114th Combat Battalion was at the lower end of the Villa Verde Trail at Santa Maria. The infantry was to advance along the trail; at the same time the 114th engineers were to transform the pathway into a combat road. Winding some 25 miles through mountains and over hogback ridges and reaching an elevation of 4,800 feet, the trail connected two points only 11 miles apart by air. The surface was hard-packed clay. Because fairly rapid construction was necessary, the engineers decided to dispense with some of the basic principles of road building. In widening the footpath, which in places clung to the sides of the steep hills, the men began cutting from the bottom of a hill instead of the top. The overhangs sometimes caved in, burying equipment. Dozers, slipping over the precipitous slopes, went down as much as 400 feet and could be recovered only with difficulty; in a number of instances, roads had to be built to
them to get them back on the trail. Although the infantrymen were well ahead of the engineers most of the time, the enemy infiltrated the rear areas on several occasions. At Kilometer 19, one of the dozers came under enemy fire; eighteen 47-mm. shells landed near the machine. Shell fragments tore many holes in the blade and body of the dozer, but caused no casualties.
On 5 March the infantry reached Salacsac Pass, where the Villa Verde Trail turned east toward Santa Fe and Highway 5. The Japanese, waiting there, made determined efforts to halt the advance; enemy machine gun fire was so heavy that no progress could be made for days. The Japanese had built numerous caves in the pass area. The engineers brought up armored dozers to prepare firing positions for tanks. Protected by their cabs, the men kept on working despite minor wounds received from bullets that found their way through the portholes. One armored dozer, working its way around a bend, ran into fire from a machine gun about twenty feet away. The operator, slightly wounded, charged the gun with his dozer. The bullets cut the cable and dropped the blade. The operator withdrew to make way for a tank, which proceeded to destroy the machine gun. The cable was quickly repaired and the bulldozer operator resumed work in forty-five minutes. The next day he buried three Japanese in caves. On the whole, working with armored dozers on the precipitous slopes of the Villa Verde Trail was dangerous because the visibility of the operators was so severely restricted. While the infantry vainly attempted to get control of Salacsac Pass, the 114th engineers continued to push forward slowly on the road and to improve the part to the rear. Dreary weeks passed while the enemy continued to hold at the pass.7
The Drive to Baguio
Meanwhile, during the first part of March, the 33rd Division was advancing on Baguio. Here, also, the work of the 108th Engineer Combat Battalion was largely road construction, but, as elsewhere, many other jobs had to be done. The Japanese had placed numerous mine fields, most of them poorly camouflaged and some so hastily laid that they were wholly ineffective. Still, the combat engineers could not take any chances and cleared twenty-five fields. The Japanese, in retreating, had destroyed most of the bridges. Wherever possible, the engineers located fords or repaired the ruined structures, salvaging such materials as they could. At one point on the Kennon Road, the Japanese had destroyed an 80-foot span over a gorge forty feet deep. The site was at a horseshoe bend, with sheer cliffs on one side, where only a 30-foot horizontal clearance at the abutment was left in which to maneuver. Instead of the usual two hours, the men needed sixteen to swing a Bailey into place.
One of the urgent missions of the 108th engineers was to seize intact the two concrete and steel bridges across the
Trucks negotiate the Villa Verde trail where engineer construction is in progress
Bauang River near its mouth on the west coast of Luzon. The two spans had to be taken undamaged if the troops were not to be unduly delayed. It was known that the bridges were mined and that the Japanese occupied positions north of the river commanding the structures. At night an infantry battalion, preceded by a platoon of combat engineers and a mine detection detachment, moved to the south bank. The infantry forded the river to attack enemy forces in Bauang. Meanwhile, the engineers crept up to the bridges. One detail removed about zioo pounds of explosives
from the stringers of the south span; it had just finished the job when it was attacked by the enemy. One engineer of the platoon was killed in the skirmish in which the Japanese were repulsed. The bridges were captured undamaged. Late in March the 37th Division was sent from its garrison in Manila to relieve the 33rd Division in its coastal positions. Everywhere, progress was painfully slow.8
Filipinos help construct a road across a ford in the Santa Cruz river, Luzon
Southern Luzon
On 14 March XIV Corps, transferred from the east central front to southern Luzon, began the drive against the enemy in that part of the island. In the vanguard was the itth Airborne Division, which had been engaged in combat on southern Luzon since its landing at Nasugbu. Enemy resistance south of Manila was weak. The division’s 127th airborne engineers constructed and repaired supply and combat roads in hilly terrain, built and repaired bridges, operated ferries, and leveled off rice paddies for cub strips. They also took care of mines and booby traps and removed explosives from several bridges. Mount Macalod, on the southeast shores of Lake Taal, and Mount Malepunyo, ten miles east of the lake, were heavily mined. On the latter mountain, bombs and shells, hung in low trees, were not discovered until a patrol stumbled over the wires. Hampered by a lack of equipment usually furnished a combat unit, the 127th resorted to expedients and maximum use of local materials to perform its missions. In mid-March elements of the 592nd Boat and Shore Regiment supported part of the 158th RCT in a series of shore-to-shore operations
that lasted almost a week and that cleared the enemy from Calumpan Peninsula between Balayan and Batangas Bays in southwestern Luzon.
With the transfer of the i st Cavalry Division from central Luzon to the Bicol Peninsula on 23 March, the 8th Engineer Squadron also transferred its activities to that area. The men carried on their usual tasks. While constructing two ponton bridges, they encountered an unusual problem. Lily pads came floating downstream in such tremendous numbers that they threatened to wreck the bridges. The men stretched cables from bank to bank to catch the pads before they reached the bridges. By the end of March southern Luzon, except the Bicol Peninsula, had been cleared of the enemy.9
Corps and Army Engineer Units
Behind the front lines, engineer units assigned to corps and army were at work. Road maintenance, improvement of bridges, elimination of pockets of enemy resistance, and some base construction were the major jobs. Close behind the combat forces moving towards Bambang and Baguio were units of the 1136th Construction Group, working under I Corps. The corps engineers kept supplies flowing to the two fronts near Bambang and Baguio, operated sawmills, and built camps for the troops to use in the coming rainy season. Because the fighting was expected to drag on well into the wet months, the group’s principal job was to develop main supply routes for all-weather use. Highway 5, breaking down under heavy traffic, was resurfaced and repaired. In the Baguio area, where Highways 3 and it required extensive work, the engineers raised roadbeds above the level of the surrounding countryside, widened one-lane sections, and installed drainage facilities. In east central Luzon, the 1112th Construction Group worked on supply routes and bridges. At the end of March, when most of the group was transferred to Sixth Army for construction in rear areas, responsibility for engineer work in the XI Corps area was transferred to the combat engineers of the two divisions. On southern Luzon, the 1129th Engineer Combat Group under XIV Corps direction furnished support to the combat units. Among its tasks were the repair of the pier at Batangas, rehabilitation of the airstrip at Lipa, and operation of a sawmill and an ice plant.10
The Eighth Army Campaign—Palawan
Meanwhile, Eighth Army had begun its campaign in the central and southern Philippines. Palawan was the scene of the first landing. On 28 February a task force, made up mainly of the 186th RCT of the 41st Division, disembarked on the eastern shore of the island. Engineer units included two companies of the 532nd Boat and Shore Regiment, elements of the i 16th Combat Battalion, and the 1897th Aviation Battalion. The assault waves came ashore at the three designated
beaches, amid some confusion, in the course of which a number of the engineer craft missed their proper landing points; but all of this was not serious, since enemy opposition was nonexistent. The beachhead was quickly consolidated. No real resistance ever developed, and the last Japanese elements were wiped out in about a month. Little combat engineering was required. The 1897th engineers began to rehabilitate the airstrip at Puerto Princesa, badly damaged by bombing, and in 19 days had it ready for fighters.11
The Zamboanga Peninsula and the Sulu Islands
After bringing Palawan under control, troops of Eighth Army seized the Zamboanga Peninsula and the Sulu Islands. One hundred and fifty miles long, the peninsula was connected with the major part of Mindanao by a narrow isthmus, and, together with the Sulus, formed a series of steppingstones to Borneo on the southwest. On to March a naval task force began a bombardment of the coastal areas east and west of Zamboanga City, forcing the Japanese to abandon their beach defenses. Shortly after 0900, the infantry, assisted by elements of the 543rd Boat and Shore Regiment, landed west of Zamboanga City and was ashore in half an hour, encountering only light machine gun fire. Zamboanga City fell the first day. Subsequently, enemy resistance stiffened and a number of bitterly contested battles were fought. Nevertheless, the American forces continually expanded the area they held. Combat engineer operations, the mission of elements of the 116th engineers, were considerable on the peninsula, where well-camouflaged pillboxes, mine fields, barbed wire entanglements, and fortified caves and tunnels were numerous. The combat engineers destroyed about 50 caves and pillboxes and removed nearly 2,000 mines. They built about 50 miles of roads and rehabilitated or constructed 16 bridges, each capable of taking 35 tons.
The 370-odd islands of the Sulus, the southernmost ones in the Philippines, were mostly small, uninhabited, and unimportant. Three were of strategic significance—Basilan, Jolo, and Tawitawi. The campaign began with the landing of elements of the 41st Division on Basilan on 16 March. Other islands were seized later, including the main one, Jolo, where the only enemy resistance worth mentioning was encountered. In these operations, elements of the 543rd Boat and Shore Regiment helped land the infantry, and the 116th engineers carried out combat missions. Except on Jolo, little combat support was needed. On that island the engineers destroyed some enemy fortifications, removed mines, repaired and constructed bridges, and built about twenty miles of road. Construction units did additional work in the Sulus and on Mindanao. The 873rd Aviation Battalion rehabilitated airfields on the Zamboanga Peninsula and the Sulus, and other engineer units began to rehabilitate numerous local facilities.12
The Visayan Islands
To gain control of the remaining Visayan Islands, McArthur planned two operations, one by elements of the 40th DIvision, to seize Panay and western Negros, and the other by elements of the Americal Division, to recapture Cebu, Bohol, and eastern Negros. The 2nd Special Brigade, the 52nd and 57th Combat Battalions, the 865th Aviation Battalion, and the 239th Construction Battalion were to provide major engineer support. The first assault began on 18 March with the landing of elements of the 40th Division near Iloilo, capital of Panay. Eight days later, the Americal Division launched the second assault near Cebu City. These operations were similar to those against Palawan and the Zamboanga Peninsula. The naval and aerial bombardments drove the Japanese away from the beaches and forced them to retreat into the mountainous interiors, from which they could, as a rule, be routed only after long and arduous Campaigns.
The most effective enemy defenses were found on Cebu, where the landing forces came ashore just south of Cebu City. Starting across the beach, the troops discovered that the area was heavily mined and expertly camouflaged. Within a few minutes, eight vehicles were blown up. With men continuing to come in, beaches were soon jammed. A disaster would have been inevitable had there been any Japanese opposition besides light rifle fire. The engineers worked frantically to open a path through the mines. In back of the beaches and on the road to Cebu were numerous obstacles, among them antitank ditches, log walls, steel rails, and more mines. The obstacles were not much of a problem because they were not covered by fire. Cebu City, like the other major cities of the central Philippines, was practically deserted. Again, construction of roads and bridge building were by far the most important jobs. The 865th Aviation Battalion on Cebu and the 239th Construction Battalion on Panay and Negros rehabilitated shattered airfields and other facilities.13
Mindanao
The only large island in the southern Philippines the Japanese still controlled to some extent at the end of March was Mindanao. A successful campaign by American forces there would mean the end of Japanese power in the central and southern part of the archipelago. The Japanese on Mindanao were already in a precarious position because of the loss of the Zamboanga Peninsula and the in-Creasing harassment of Filipino guerrillas, led since 1942 by Colonel Fertig. In February 1945 Fertig had under his command some 33,000 men, half of them armed. Like the Visayan Islands, Mindanao offered many good opportunities for defense. Much of the island was mountainous, jungled, and swampy. Because of the relatively large size of the island, its few good roads, and its complete lack of railroads, overland operations would be extremely difficult.14
Assault planners tried to take advantage of the few favorable terrain features. An invasion of the east coast would be
impractical because of the high surf, the rugged shore line, and the almost impassable mountains farther inland. The north coast had many good beaches, in particular at Macajalar Bay, but high ground farther inland would give the defending forces a decided advantage. A major handicap on the southern coast would be inadequate communications with the remainder of the island. On the west coast were many good beaches and anchorages, and from this part of the island the interior was most accessible. Consequently, the initial assault was planned for that coast.
On 17 April two divisions of X Corps, the 24th and the 31st, landed near Parang. The 24th Division, with the help of guerrillas, advanced eastward along the highway leading to Davao. At the same time the 533rd Boat and Shore Regiment of the 3rd Special Brigade, together with naval units, moved some of the troops up the Mindanao River to secure the Fort Pikit—Kabacan area in the central part of the island, through which ran the Sayre (North-South) Highway. On 26 April elements of the 24th Division reached Davao Gulf, not far south of Davao, turned northward, and occupied their objective on 2 May. Meanwhile, the 31st Division had started up the Sayre Highway to split the Japanese forces in the northern part of the island. On 10 May, at Macajalar Bay, at the northern terminus of the highway, a second amphibious force came ashore and headed south. Everywhere Japanese troops were forced to retreat into the almost impenetrable jungles of the interior.15
“The engineer problem on ... Mindanao began with bridges and ended with roads,” said one engineer report. The story of the 3rd engineers of the 24th Division, almost from the time they landed until they reached Davao was one of “... bypassed bridges, rebuilt bridges and newly constructed bridges, of frantic efforts to get bridge timber and Bailey up forward. ...” The 106th engineers of the 31st Division likewise were occupied mainly with roads and bridges. Their first job was to improve the road net in the vicinity of the landing area. When the 31st Division started up the Sayre Highway from the Fort Pikit—Kabacan area, the 106th engineers, transferred to the highway a company at a time, furnished increasing support.16
In worse shape than the roads were the bridges. Between Kabacan and the first gorge, twelve miles to the north, demolished structures spanning shallow streams were either bypassed or hurriedly repaired to make rapid progress possible. The first real gorge, 120 feet across and 35 feet deep, with the bridge in ruins at the bottom, was a more serious obstacle. Stringing a cableway downstream from the site of the bridge, the engineers got jeeps, ¼-ton trailers, and howitzers across. Heavy vehicles would need a bridge. Because of the depth of the gorge, construction of a timber trestle was not practicable, and erection of a Bailey would be laborious, if not impossible. The men solved the problem in an ingenious way. They blasted out the sides of the gorge at the two approaches; the debris filled the gorge and made a crossing possible. The job was finished
in two days and two nights. The combat engineers had numerous chores in support of the infantry, arising from the fact that the Japanese had fortified strategic points with systems of caves and pillboxes and that enemy camouflage was excellent. Base construction was kept to a minimum, but as elsewhere, airfields and other facilities were rehabilitated.17
Borneo
As early as October 1944 the Allies had planned to seize certain areas of Borneo to deprive the enemy of vital oil supplies and to construct bases from which to cut Japanese communications with the Netherlands Indies. Plans called for three attacks, the first against Tarakan Island on 17 May, the second against Brunei Bay on 10 June, and the third against Balikpapan on 1 July. These assaults were assigned to Australian and Dutch troops, supported by American naval forces and elements of the 3rd Special Brigade. The 26th Australian Brigade and a company of the Royal Netherlands Indies Army took part in the operations against Tarakan. The first troops were put ashore on 30 April without opposition on Sandau Island off the east coast after withering naval and air bombardment had blasted the main landing area. Engineers and naval personnel went in and breached offshore obstacles in twelve places to permit LSTs to land. The Japanese did not try to defend their beach positions, and, after attempting to make a stand about 1,500 yards inland, were driven into the interior. Royal Australian Engineers had combat and construction duties.
At the Brunei Bay landing on to June, the task force included units of the 9th Australian Division. After the naval bombardment, landings were made unopposed. In view of the fact that the Brunei Bay landing would sever north-south communications, enemy reaction in this area was remarkably weak, being limited to only a few harassing air raids. The amphibian engineers were hampered somewhat in unloading operations on Labuan Island by the narrow roads and swampy conditions near the beaches. Elsewhere at Brunei Bay, landings were easily made. It was expected that the landing at Balikapan would be equally successful.18
The End of Organized Resistance on Luzon
Meanwhile, on Luzon the Japanese were being compressed into smaller and smaller areas. In mid-April the four divisions striving to reach Baguio and Bambang were still stalemated. Those on the Bambang front were tied down at Balete and Salacsac Passes, while in the Baguio area, the 33rd’s advance had progressed only a few miles up the strongly defended Kennon Road, and the 37th Division was having just as hard a time moving in from the coast. Engineer tasks in support of the infantry were as strenuous as before. The first breakthrough in the Baguio area came on 21 April when the 37th Division cracked resistance on Highway 9 at the Irisan River
Engineers use a Japanese Truck to support a temporary bridge in the Cagayan valley
gorge, and together with the 33rd DivIsion, took Baguio five days later. On 5 May the 37th Division was transferred to the Bambang area, where the Japanese were still holding up the 25th and 32nd Divisions. The job still requiring the greatest effort was the Villa Verde Trail, where the rains which began in late April compounded the difficulties. In May, the downpours increased in intensity, and work on the trail became impossible. The engineers reported, “... dozers dug themselves in as their tracks revolved without traction. ...” On 13 May the 25th Division finally captured Balete Pass. Reaching Santa Fe twelve days later, it turned west onto the trail and headed toward Salacsac Pass. Meantime, after a 3-month struggle, the 32nd Division broke through enemy strongpoints at the pass. On 29 May the two divisions met. Further engineer work on the trail had been halted three days previously, and all effort was henceforth spent on keeping open the part that had been improved.19
The stage was now set for the final drive down the Cagayan Valley. The plan was to have the 25th and 32nd Divisions
remain at Bambang and most of the 33rd Division at Baguio to clear out pockets of resistance. The 37th Division was directed to pass through the 25th Division and spearhead the drive north on the highway. It left Santa Fe on 31 May and made good time, averaging five or six miles a day. The 117th Engineer Combat Battalion had to move forward every two or three days to keep up with the infantry. Highway 5 was in fair condition, but most of the bridges were out. The company farthest forward operated treadway ferries until permanent crossings could be built, put in bypasses and culverts, and made minor road repairs. The next one along made major repairs to bridges, put gravel on bypasses, and occasionally built new bridges. The men put a floating bridge over the Magat River at Bagabag, some twenty miles north of Bambang. The 117th engineers also built several airstrips. At Bayambang, they blocked off a portion of a graveled roadway to serve as a runway; at Bagabag one hundred natives removed grass from an existing strip and filled small shell holes. The engineers were favored by the terrain in the flat, open valley, but the heavy rains were a major hindrance.20
To keep the enemy from escaping by way of Aparri, a small group of Filipinos and Americans—called the Connolly Task Force—had been organized to go rapidly up Highway 3 along the western and northern shores to Aparri. Engineer reconnaissance parties learned that much work would have to be done on the highway to permit the convoy of 200 vehicles to reach its goal. Two platoons of the 339th Construction Battalion went ahead of the main force, by road and by LCT, to repair bridges, remove landslides, and widen the road. The engineers also erected two hospital ward tents, built an all-weather airstrip, and installed and operated ferries.21
In east central Luzon, the advance was slow. Early in March the 43rd Infantry Division replaced the 1st Cavalry Division, which had been transferred to southern Luzon. On the 14th of the month XI Corps assumed command of the operation. An engineer company of the 6th Battalion had an unusual task on Mount Pacawagan, one of the numerous peaks on which fighting took place, and where the only possible route for a trail was along a hogback ridge. The men managed to get motorized compressors up the steep sides to drill holes in rock outcroppings, and then placed explosive charges in the holes to blow up the rock and make a roadway. They used i 00 smoke pots to screen their work from the enemy close by.
Early in May the final push began. The 38th Division with the 113th Combat Battalion headed for Montalban Dam, while the 43rd was deployed from the rear to take Ipo Dam. Road improvement continued to be the major job in support of the infantry. With the seizure of Ipo Dam on 17 May and the capture of Montalban on the 28th, both of them intact, the campaign in the Sierra Madres was virtually over. The engineers, even though they had not always been able to keep the infantry on the
move, had contributed much to final victory.22
Fighting continued in southeastern Luzon. On i April units of the 2nd Special Brigade landed the 158th RCT without opposition at Legaspi, near the tip of the peninsula. Squads of the 1279th Combat Battalion cleared the beach of mines which had not been detonated by the preinvasion air assault. The infantry started inland but was soon halted by the enemy near Daraga, a few miles northwest of Legaspi. While fighting raged, the combat engineers set about reconditioning the airstrip at Legaspi for evacuation of the wounded. Under enemy fire the first two days, the men cut grass, dug drainage ditches, and filled twenty large bomb craters with wreckage from the port. The strip was ready for operations on 6 April. Two days before, the engineers had started rehabilitation of the railroad. About 600 Filipinos, using hand tools supplied by the engineers, restored the shops and replaced tracks while the troops concentrated on bridge construction. On 10 April resistance at Daraga collapsed. The advance continued northwest on the Bicol Peninsula, where there were many well situated but poorly camouflaged mine fields and numerous roadblocks. On 12 April the 158th attacked the main Japanese force in the Cituinan Hills near Camalig; the same day the 1st Cavalry Division entered the Bicol Peninsula from the northwest. On 2 May elements of the 158th RCT and the 1st Cavalry Division met at San Augustin, and on 16 June, the Bicol Peninsula was declared secure.23
Before the end of June the Japanese on Luzon were almost completely crushed. On the 8th of that month, with organized enemy resistance in the east central part of the island at an end, the 6th Division, including the 6th Combat Battalion was transferred to the Cagayan Valley. The 6th Division started up the highway behind the 37th. At Bagabag the two divisions turned northwest on Highway 4 toward Kiangan, where remnants of the enemy were gathering. Fighting was approaching an end in northern Luzon. On 21 June Connolly Task Force, which had moved up the west coast, reached Aparri. Reinforced by one battalion of the 11th Airborne Division, it started south on Highway 5 two days later, and on 26 June its patrols met advance elements of the 37th Division at Alacan, twenty-five miles south of Aparri. The two units then started east to search for the enemy in the mountains. There were still some 65,000 Japanese left in northern Luzon, but they were largely unorganized and scattered. On 1 July Eighth Army relieved Sixth Army to carry on mop-up operations. Eighth Army also continued with mop-up operations in the southern Philippines. The operation against Balikpapan was carried out as scheduled on 1 July.24
Iwo Jima
Meantime, decisive combat and amphibious operations had been under way closer to the Japanese homeland. The islands of Iwo Jima and Okinawa, the former 800 miles south of Tokyo and the latter 900 miles southwest of the Japanese capital, had come under assault. Both were in the Pacific Ocean Area.
Admiral Nimitz had decided on the capture of Iwo Jima principally for two reasons: to make it impossible for the enemy to use the island as a takeoff point from which to bomb American bases in the Marianas, and to provide B-29 fields which could stage bombers headed for Japan and at the same time enable crippled planes returning from missions to make emergency landings. The capture of the island, and most base construction as well, was assigned to the marines and the Navy. Plans called for building three airfields: a large one with two runways for B-29’s in the center of the island, and two fighter fields with 5,000-foot runways north and south of the B-29 field. Most of the work was assigned to Seabee units. One engineer construction unit—the 811th Aviation Battalion—was scheduled to be sent in.25
The assault began on 19 February. After three weeks of bitter fighting, the island was secured on 16 March. The 811th engineers, the first Army unit to arrive, landed in mid-April and on the 27th of that month took over construction on North Field from the Seabees. (Map 30) The aviation engineers found that Iwo Jima (Japanese for Sulphur Island) was unusual insofar as terrain was concerned. Five miles long and two and one-half wide, it was of volcanic origin. Mount Suribachi, an extinct volcano 550 feet high, formed the southern tip. The northern half of the island was a flattened dome about 400 feet above sea level. Coral, usually found in this latitude, was absent. The surface of Iwo Jima consisted of volcanic ash, in various stages of consolidation, with the hardest resembling soft sandstone. Steam vents were numerous, and just a few feet under the surface, the ground was quite hot. When the 81 th engineers took over construction on North Field on 27 April, the runway was operational, but they still had much work to do on the field. Principal tasks included the building of taxiways, parking areas, warehouses, and roads.26
Okinawa
Stretching for approximately 600 miles from Kyushu to Formosa was a chain of islands known as the Ryukyus. Almost in the center was Okinawa, some 60 miles long and 3 to 10 miles wide, which the Joint Chiefs had for some time been considering as a site for an amphibious assault. The capture of this island by the United States would have grave consequences for the Japanese Empire. Control of Okinawa would enable American forces to develop airfields and bases from which to deliver crushing attacks on enemy communications and industrial
Map 30: Iwo Jima
centers. If the Japanese lost the island, their lines of communications with southeast Asia and the Netherlands Indies would be cut, whereas Allied communications with China would be secured. With Okinawa gone, the Japanese would not be able to carry on the war much longer.
Terrain
Favorably located from the strategic point of view, Okinawa was not the best site for an amphibious assault. It was a rough, generally mountainous, coral island. (Map 31) The northern two-thirds consisted almost entirely of rocky terrain, which aerial photographs indicated was covered by forests and heavy undergrowth. The southern one-third, not so mountainous, consisted in part of gently rolling country broken by ravines and limestone cliffs. About 80 percent of southern Okinawa was under cultivation, mostly in sugar cane and sweet potatoes. Along the coasts were rice paddies. The island’s shoreline was precipitous; mouths of streams broke the steep slopes in only a few places. Good landing beaches were scarce, the most likely ones being on the east coast at Nakagusuku Bay and on the west coast between Hagushi and Itoman. In back of these beaches were flat areas consisting principally of rice paddies—a potential hazard to vehicles. Most of the few roads and trails ran along the coast. Because of the rocky nature of the island, stone for road surfacing would in all probability be easy to obtain. Deposits of coral and of slate, conglomerate, and other types of rock were believed to be plentiful. There were small streams but no rivers. Since most of the waterways could be waded, they would scarcely be an obstacle from a military standpoint, and bridging, consequently, would be relatively easy. Rainfall was plentiful and occurred throughout the year, with the heaviest downpours taking place between May and September. From May to November, typhoons could be expected. The only city of any size was the capital, Naha, with a population of about 65,000. The slow reduction of enemy forces barricaded behind stone walls of an extensive urban area, which had been the case in Manila, was not anticipated.
Map 31: Okinawa
However, throughout the island, each house with its outbuildings was, as a rule, surrounded by a dense row of trees and often by a stone wall, ideally suited for defensive fighting. There were numerous burial vaults which would provide advantageous positions for the enemy.27
Engineer Planning
The capture of Okinawa had been assigned to Tenth Army. (See Map 31.) Consequently, Brig. Gen. George J. Nold, formerly engineer of the Alaskan Department and since June 1944 Engineer, Tenth Army, was responsible for overall planning for combat engineering. He and his staff had begun work in mid-October 1944. Since they expected combat support to be largely routine, they did not have to engage in extensive planning. The major concern of the
planners was obtaining enough engineer troops to provide adequate support for the initial amphibious assault and subsequent overland movement. Because only about 70 percent of the units requested were available, some adjustments had to be made.28
Planning for base construction on Okinawa was a complex matter. Since both the Army and the Navy wanted numerous facilities, the engineers in Hawaii had to make detailed calculations regarding location and size. The airfield program alone was tremendous. Six B-29 runways were to be built, together with a depot field, for the long-range heavy bombers. Also planned were 6 heavy bomber, 2 medium bomber, and 2 fighter runways, all to be constructed of coral. To support such an airbase storage tanks for about 1,800,000 barrels of gasoline, 6,000,000 square feet of warehousing, 12,500 hospital beds, housing for 375,000 men, 700 miles of road, and extensive harbor facilities at Naha would be needed. Estimates were that ninety engineer units would have to be sent to Okinawa to finish this construction on time. Higher headquarters also considered it advisable to put base facilities on small nearby islands. Those on Ie Shima, about two miles off the northwestern coast of Okinawa, would be the most extensive.29
For the assault on Okinawa, two corps were assigned—the Army’s XXIV Corps, including the 7th and 96th Divisions, and the Marine Corps III Amphibious Corps, consisting of the 1st and 6th Marine Divisions. In reserve were the 2nd Marine Division, afloat, and the Army’s 27th Division at Ulithi. The plan of campaign was a model of simplicity. Prior to the attack, Tenth Army’s 77th Infantry Division was to seize a number of small islands to the west—the Kerama Islands—where naval anchorages would be provided. Landing on the west side of Okinawa near Hagushi, both corps, the III Amphibious on the left and XXIV on the right, were to drive eastward clear across the island. Then the III Amphibious Corps was to turn north and destroy Japanese forces in the northern part of Okinawa; XXIV Corps would turn south, and drive the enemy forces toward the southern tip of the island until they surrendered or were destroyed. Since the Okinawa operation was to be carried out by Pacific Ocean Area forces, the island command or garrison type of organization for base construction was set up. Engineer units assigned to the garrison force for base construction were scheduled to land early.30
Planning for Amphibious Operations
The landings in this assault would differ from those in the Central Pacific Area in that an engineer special brigade organization was to be used. This was the Headquarters and Headquarters Company of the 1st Brigade, redeployed in late 1944 from France, and now under the command of Colonel Talley, formerly
in charge of construction in Alaska. The 1st Brigade differed considerably from the special brigades of the South-west Pacific. It was a shore organization only and had been converted from an amphibious-type unit while it was still in England preparing to engage in the 1942 North African campaign. Later, the only part of the brigade to be retained permanently was the Headquarters and Headquarters Company. For each operation, engineer combat battalions, and quartermaster, signal, ordnance, and medical units were attached. The organization of the 1st Brigade thus fitted in well with the Central Pacific’s shore party type of organization. The plan was to place the shore parties of XXIV Corps and III Amphibious Corps under the headquarters of the 1st Engineer Special Brigade.31
Operations to Mid-April
The Okinawa campaign began on 26 March. On that day, elements of the 77th Division landed on five of the islands of the Kerama group. The 302nd Combat Battalion supported the division; a company or a platoon was attached to each of the battalion landing teams. Missions were easily accomplished, including the provision of the usual support for the infantry and the destruction of enemy installations, equipment, and supplies.32
On the morning of April at 0830, XXIV Corps and III Amphibious Corps landed on the west coast of Okinawa near Hagushi. Weather and sea conditions were almost perfect. The only obstacle was a coral reef extending along the entire length of the 6-mile-long assault beach. Since the heavier landing craft could not cross over, men and cargo were transferred to LVTs and Dukws, but in some places even Dukws had difficulty crossing the barrier until the engineers prepared passageways with explosives and bulldozers. Japanese resistance was surprisingly light, the enemy laying down only occasional artillery and mortar fire, which caused few casualties and did little damage. As was so often the case elsewhere, infantry intrenchments, pill-boxes, and other defensive positions near the beaches were not occupied. About 2,000 posts had been placed along the southern part of the reef; apparently they were to have been strung with barbed wire, but no wire was found and the posts were easily removed. Once more, natural obstacles were more formidable than the enemy. Reefs, bluffs, and seawalls caused the troops to be jammed along the shore. Colonel Talley and his staff, initially using the shore party units of XXIV Corps and others assigned to the Island Command, were soon busily engaged in directing the unloading of supplies and moving them to dumps. Because the organization had too little time to work together as a team, there were some difficulties. Confusion in unloading was the result, in part, of the limited time available for planning and for integrating the organization. There was a noticeable shortage of Dukws and LVTs to haul supplies over the reef.33
Engineer Combat and Amphibian Support
As the troops moved inland, Japanese resistance continued to be light, and by noon of the first day, the troops had captured Yontan and Kadena airfields. By evening, some 50,000 men were ashore. The next day, again in the face of light resistance, the 7th Division reached the east coast. III Amphibious Corps now veered north, and XXIV Corps, south, and began their drives to the tips of the island.
During the next few days, the troops generally made rapid progress. On northern Okinawa, largely because the infantry advanced so swiftly, the major task of the Marine engineers was road repair. Before long, division and corps units were charged with the maintenance and repair of more than I oo miles of concrete highway. More bridging was required than the nature of the terrain had led the planners to expect. The engineers repaired damaged structures, mainly by putting in cribbing and timber supports, and replaced completely destroyed bridges with Baileys. Fords, dikes, and causeways were used whenever possible as temporary expedients. Mines and fortifications were almost entirely lacking. Water supply was sometimes difficult because of the rapid advance of the troops and the few satisfactory sources of water. Rehabilitation of Yontan airfield began on the second day.
On southern Okinawa, also, as XXIV Corps moved southward, division and corps engineer missions were light. Enemy resistance in any real sense did not materialize. The engineers had to give most attention to the roads in the interior of the island, where, narrow and only partly paved, they soon crumbled under heavy traffic. Division and corps engineers improved them with coral and rubble from the buildings of native villages. The 13th Combat Battalion of the 7th Division began rehabilitating Kadena airfield the day after the landing; the next day an aviation battalion took over; four days later the runway was operational. As the troops of XXIV Corps penetrated farther into the southern part of the island, they found increasing numbers of mines. Some were plastic; many were aerial bombs equipped with pressure detonators. Roadblocks, consisting of ditches, felled trees, and junked equipment, became common. The troops also came upon more booby traps. These various obstacles were no great hindrance to the advance of the troops in the first days of the assault.34
By mid-April operations on Okinawa were progressing well. All of the northern part of the island was in American hands, except isolated pockets of resistance on Motobu Peninsula. The troops were advancing toward the southern tip, though at a slower pace and against mounting enemy resistance.
Logistical support was proceeding satisfactorily. On the 9th, the 1st ESB had assumed control of all shore party operations in the XXIV Corps area and was scheduled to take over control of all unloading
on Okinawa, including that in the Marine beach areas, on the loth. The brigade in landing troops and unloading supplies had experienced occasional fire from the enemy. In general, amphibian operations on Okinawa indicated that an ESB headquarters company with temporarily attached units could not operate as efficiently as a complete brigade with permanently assigned boat and shore elements.35
Combat Support on Ie Shima
On 16 April two regimental combat teams of the 77th Division landed on Ie Shima. Daily aerial reconnaissance during the two weeks before the assault disclosed so few signs of enemy activity that it was widely assumed the island had been evacuated. When the first assault waves hit the beach, they found Ie Shima anything but abandoned. Enemy resistance was savage; even civilians armed with hand grenades and sticks took part in the fighting. The third regimental combat team, less one battalion, was sent in to reinforce the first assault troops. Elements of the 302nd Combat Battalion, attached to their respective combat teams, were busy reducing obstacles, removing mines, and destroying caves and pillboxes, and at times, fighting as infantry in hand-to-hand combat. The island was strewn with all types of mines—antipersonnel, antitank, and antiboat. The two airfields were heavily mined. The enemy made extensive use of aerial bombs, which were buried in the ground with fuses pointed upward. Improvised mines, consisting of 5-gallon cans of explosives fitted with a pressure-type fuse, were numerous. During the final stages of the campaign in the rugged eastern part of the island, the troops had to destroy hundreds of caves, some of them cut in the sides of cliffs and two or three stories high. The 302nd engineers during the fighting on Ie Shima removed about 2,600 land mines, and reduced 560 caves, pillboxes, and dugouts. For the 302nd this was the bloodiest fighting of the Pacific war. The battalion suffered men killed and 49 wounded. The island was finally secured on 21 April, but even after that mop-up operations were necessary.36
Southern Okinawa
Also on 21 April, three weeks after the initial landing, organized resistance on northern Okinawa came to an end. Fighting was over considerably ahead of expectations. But on southern Okinawa, a different story developed. South of a line running roughly from Kuba to Isa, in terrain admirably suited for defensive warfare and delaying tactics, the Japanese had constructed a defensive system so expertly devised as to be described as “fantastic.” Here the enemy, well entrenched in a rocky area honeycombed with caves and studded with pillboxes, blockhouses, and mine fields, put up a tenacious resistance. Not only was opposition on the ground formidable,
but also day and night air raids, including attacks by kamikaze dive bombers, and assaults by suicide boats and even swimmers harassed the American forces. In late April the 77th Division relieved the battle-weary 96th, and the 27th Division relieved the Marine 1st Division. On 8 May the latter returned to the lines and the Marine 6th Division was also sent in. There was now a two-corps front.37
Combat engineer tasks on southern Okinawa had been fairly easy up to now, but this was not to be the case henceforth. Only through hard fighting and with constant support of the combat engineers could the infantry make any headway at all. The enemy’s defense tactics were among the best encountered so far. One of the principal elements in the defense was cave warfare. On southern Okinawa the Japanese developed this type of fighting to the highest degree in the war. Many of their caves and other fortifications were on the sides of hills and cliffs away from the approaching American forces. The openings from which weapons were fired were so small as to be almost invisible. The enemy placed machine gun and mortar fire on the tops of the hills and ridges over which American troops had to advance to reach the mouths of the caves. Probably the greatest improvement made by the Japanese was to cover cave openings by fire. This was done in various ways. The most successful tactic was to make caves mutually supporting, with the entrance of each cave covered by fire from others located to the front and flanks. Sometimes machine guns, mortars, and even artillery would be emplaced in the open to cover cave entrances. The various weapons were, as a rule, so cleverly camouflaged that they were difficult to find. In the last desperate effort to prevent the destruction of caves by American forces, the Japanese would engage in grenade duels and hand-to-hand combat.
A number of weaknesses in cave warfare remained. For one thing, the small entrances greatly restricted the defenders’ field of fire. The lack of communications between caves limited the defenders’ ability to maneuver, counterattack, or withdraw. Japanese commanders cautioned their troops not to be trapped in caves. At the proper time at least one-third of the men were to leave and help cover the cave mouth from emplacements. But the defenders had little success in carrying out such orders. The Japanese were aware of the weakness of cave warfare, but had adopted it because of the overwhelming U.S. fire power and because of the chance cave warfare provided for slowing down the advance of the U.S. forces. The Japanese were making every effort to improve cave warfare and at the same time overcome its disadvantages.
The U.S. infantry-tank teams destroyed innumerable caves by using direct fire and flame throwers. The 8-inch howitzers of the artillery, and, at times, bombardment by aircraft proved very effective. The combat engineers were widely used to reduce caves and fortifications that could not be destroyed by direct infantry assault, artillery fire, or aerial bombardment, but had to be eliminated by hand-placed explosive charges. Engineer demolitions personnel
were organized in much the same way as in previous assaults in the Central Pacific. Usually a squad of from six to twelve men was responsible for front-line demolitions for an infantry unit as large as a battalion. If intelligence indicated numerous caves, pillboxes, and blockhouses in an area, an entire engineer platoon might be directed to support one infantry battalion. The battalion commander usually kept his engineer demolition teams near his command post in order to have them readily available should the infantry need help. While waiting to be called forward, the men prepared 24-pound satchel charges, which were the ones mainly used on Okinawa. Pole and shaped charges were, as a rule, too unwieldy or too heavy.
Called forward, an engineer squad operated in a more or less standard manner. The man in the lead advanced toward the cave with the charge and phosphorous grenades, followed by one or two others with spare satchels; the remainder of the group took up positions as directed by the squad leader. The infantry was in readiness to deliver protective fire. Reaching the mouth of the cave, the lead man threw in phosphorous grenades to blind the occupants. Next, the satchel charge was thrown in—as far as possible toward the rear of the cave—to get the maximum blast effect. Ten-to-fifteen-second delayed fuses gave the men a chance to get away from flying debris. The use of multiple fuses, some of which were dummies, made it difficult for the occupants, already at least partially blinded by the phosphorous grenades, to pull the proper fuse out of the charge before it exploded. Sometimes a second charge was thrown before the smoke of the first had cleared away. The aim was the complete destruction and sealing of the fortification. Moving in rapidly on the target and getting away fast were essential. Operating in this way, the engineers in the support of one front-line infantry battalion often used more than a ton of explosives to destroy about forty pillboxes, caves, bunkers, and ammunition dumps. Casualty rates were high. The Japanese brought intense fire to bear on demolition teams. During one 3-week period, for example, one engineer combat battalion suffered so percent casualties.38
The defenders of southern Okinawa made extensive use of mines. The American forces found no fields laid in a regular pattern, but standard and improvised mines were scattered about in great profusion. The only new type was the antipersonnel fragmentation mine. All mines, including those that were booby-trapped, were removed by 4-man engineer teams, one team being assigned to each tank platoon. Long demolition “snakes” attached to tanks were used in a few instances to clear paths through mine Fields. Armored bulldozers were extensively used to clear roads of obstacles. Booby traps were found in caves and sometimes in abandoned tanks.
Road maintenance in southern Okinawa was an arduous task for the engineers because the poorly surfaced thoroughfares broke down rapidly under the heavy traffic. From i 10 to 12 feet wide, most of the main highways were coral surfaced. During the prolonged
rains in May, maintenance became critical; in the XXIV Corps area, the engineers could keep but one main supply route open, and even this was possible only because corps and divisional engineers worked on the route continuously. After the rainy season, maintenance problems on roads were less serious, but bridging remained a major task. Bridges and culverts, almost invariably built of stone or reinforced concrete, and with a capacity of thirty-five tons or more, were adequate for much of the military traffic, but most bridges were only one lane. Baileys, used extensively on southern Okinawa, proved very satisfactory. There was little need for ponton bridges, and only three were put in place.39
The End of the Okinawa Campaign
Bitter fighting continued during May, and casualties were heavy as the defenders were pushed back slowly to the tip of the island. In June enemy resistance crumbled more rapidly. By the end of that month the Japanese position was hopeless. As the Americans pressed into the southernmost part of Okinawa, some of the defenders made last-ditch charges against American positions; many committed suicide. On 2 July the Okinawa campaign was declared officially ended.
Base and Airfield Construction for the Assault on Japan
While fighting was still in progress in the Philippines and on Okinawa, the
engineers in the rear areas were already building up bases and developing airfields from which U.S. forces were to launch the final assault on Japan. Two theaters, the Southwest Pacific and the Pacific Ocean Areas, were to be jointly responsible for the final assault. The major construction, by far, was being done in the Philippines and on Okinawa. In the meantime, finishing touches were being put on work in Hawaii and other islands of the central Pacific to support the attack on the Japanese home islands. Elsewhere, construction had slackened off greatly or stopped entirely. Some work was still in progress in the CBI theater, but in the South Pacific, the engineers were mainly dismantling bases.
Overall Organization in the Pacific
Despite changes in the tactical commands, no great modifications were made in the engineer organization in the Pacific in late 1944 and 1945. The greatest changes resulted from the Joint Chiefs’ activation of Army Forces, Pacific (AFPAC), on 6 April 1945, under the command of General MacArthur. Henceforth, all Army units in the Pacific, except those of the Strategic Air Forces, were under MacArthur’s direction. For the time being, the new command was only a nominal one since no immediate changes in organization were made. In the Southwest Pacific Area, GHQ SWPA continued to function as MacArthur’s headquarters for that theater, and MacArthur and Nimitz agreed that U.S. Army units in the Pacific Ocean Areas would remain under Nimitz’ control until he released them to MacArthur. Admiral Nimitz did not transfer the first
POA units to AFPAC until 31 August 1945, when MacArthur assumed command of all Army units in the Ryukyus, except those assigned to the Strategic Air Forces.
Engineer Organization—SWPA and AFPAC
When AFPAC was established, the forward echelon of Casey’s office was located in the Manila City Hall; the rear echelon was in the midst of moving from Leyte to the Philippine capital. Authorized strength of the office was 65 officers and 114 enlisted men. In April Casey’s request for an increase of 50 percent in personnel strength was granted. As Chief Engineer, SWPA and AFPAC, Casey had theoretical technical supervision over all U.S. Army and Allied engineer units in the Pacific. Probably his major task in his new position was to coordinate the activities of units insofar as possible in order to prevent duplication of effort. Coordination was especially necessary with regard to mapmaking organizations. In both the Pacific Ocean and Southwest Pacific Areas, they were already at work on or were about to be engaged in an extensive mapping program of the Japanese home islands.40
OCE USASOS
The office of General Ross, Chief Engineer, USASOS SWPA, had finished moving from Brisbane to Hollandia in November 1944. By this time, an ad vance echelon was already at Tacloban, Leyte; thereafter, additional elements moved forward, and by February 1945 the entire office was settled in Leyte. General Ross was now making preparations to move forward again, this time to Manila. An advance echelon, headed by Col. O. N. Rinehart, arrived in the Philippine capital in February. In April Col. Louis J. Rumaggi and the Operations Division, together with supplies and equipment, were flown there. They took over the third floor of one of the buildings of Far Eastern University and in a short time “were carrying on business as usual.” That same month OCE USASOS was officially set up in Manila.41
Engineer Districts
Since construction in the Philippines was to be so extensive and vitally important, proper organization would be highly essential. Especially in and around the metropolitan area of Manila, an immense amount of construction and reconstruction was necessary. As in Australia and New Guinea, General Frink, the commander of USASOS, organized bases to decentralize operations. He set up five, one on Leyte (Base K), three on Luzon (Base M at Lingayen Gulf, Base X at Manila, and Base R at Batangas), and one on Cebu (Base S). To supervise their operations, he had redesignated the Army Service Command, recently transferred from Sixth Army to USASOS, as Luzon Base Section, made it an intermediate headquarters, and placed it over
the bases. In April Luzon Base Section was renamed Philippine Base Section. In Australia and New Guinea, where engineer construction had been the responsibility of base section and base commanders, staff engineers exercised only technical supervision over engineer work. In the Philippines, engineer construction, initially the responsibility of the base commanders, was subsequently entirely divorced from their activities. It was assigned to engineer districts, which were similar to such organizations in the United States. To accomplish construction on Leyte, General Frink set up the Leyte Engineer District in February 1945 and made it directly responsible to General Ross. That same month, General Frink organized the Luzon Engineer District (LUZED) under Col. Alexander M. Neilson, placed it under Luzon Base Section, and made it responsible for USASOS construction on Luzon. Both districts differed from similar organizations in the United States in only one major respect—engineer troops and not contracting firms or civilian workers did the actual construction.42
The Engineer Construction Command
For some time considerable thought had been given to putting all engineer construction in the USASOS area under one command to be headed by an engineer. Generals Casey and Sverdrup and other members of MacArthur’s staff had discussed the desirability of making such a move in late 1944 and early 1945. Such an organization would be in line with the War Department’s policy of centralizing control of major technical activities in Headquarters, SOS, rather than delegating control of them to commanders of bases and advance sections, a policy the CBI theater had already implemented early in 1944.43 Sverdrup, made a major general on 5 January 1945, was especially interested in setting up such a command; it was generally assumed he would head it after Casey returned from the Army Service Command to his position as MacArthur’s chief engineer. On 20 February 1945, Sverdrup wrote Casey that it was “… rather obvious that a concentration of all construction forces within one organization is advantageous as centralized control properly exercised means far greater efficiency.” Sverdrup had in mind a construction command which would have under it various engineer districts. Two were already in existence and Sverdrup thought perhaps three more should be created. All would use troop units or contractors to get the work done. A fourth, organized along similar lines, would make use of Filipino workmen for rehabilitating Manila.44 A major question was whether to place such a command in GHQ, in USAFFE, or in USASOS. It was finally decided to put it directly under General Frink, since, as commanding general of USASOS, he was responsible for construction in the communications zone.
On 6 March the Engineer Construction
Command (ENCOM) was set up under Sverdrup, who was henceforth responsible for coordinating and supervising all construction in the Southwest Pacific that was under the control of USASOS. This meant, in effect, responsibility for construction in the Philippines, since the rear bases were by this time being dismantled. Engineer construction responsibilities in the communications zone in the islands were thus placed under one engineer command, which was completely separate from the base organizations. The men for Sverdrup’s new headquarters were taken on a temporary basis, mostly from the 5202nd Construction Brigade and from a number of aviation and construction battalions. The Leyte and Luzon Engineer Districts were transferred to ENCOM.45
The General Engineer District
A new engineer district for ENCOM was soon organized. Its establishment had, in fact, been under consideration since late 1944, when it seemed likely that an extraordinary effort would have to be made to rehabilitate and reconstruct facilities in and around Manila after the Japanese there had been defeated. Colonel Lane, chief of Sverdrup’s Operations Division, was one of the first to suggest using a district organization to rehabilitate the Philippine capital. He wrote Sverdrup on 26 November 1944: “In connection with plans for rehabilitation of Manila, it has occurred to me that it may be desirable to establish an Engineer District Office ... and that the Chief of Engineers could probably furnish a complete District with all personnel for this work. ...” Lane stated that such an organization should plan to use as many Filipino civilians as possible in order to free the troops for more direct combat support. Since local contracting firms would in all likelihood not be available, large numbers of hired laborers would have to be used.46 On 5 December MacArthur radioed a request to the Chief of Engineers for an organization similar to an engineer district office in the United States. “The limited number of engineers at my disposal,” MacArthur pointed out, “will be fully occupied in direct support of the campaign. ... This means that the maximum use must be made of civilian labor.”47
In line with MacArthur’s request, Reybold began recruiting men for the new office. Some 150 officers and 300 enlisted men were supplied by division and district offices in the United States. They received a few weeks training at Fort Belvoir and then flew to Manila, arriving in late March. Headed by Col. Robert C. Hunter they were designated the General Engineer District (GENED). It was hoped that at least some of the reconstruction projects could be given to local contractors, but this idea was quickly given up. There were few Philippine construction firms before the war and these were now unable to do any effective work because of the dislocations
caused by the conflict. Colonel Hunter had to rely at first on hired labor. He had the usual difficulties of organizing and supervising such a large work force. Fortunately, many of those hired had been employed by the U.S. Army before the war and so had gained experience for the work they had to do. Because of the vast amount of destruction, however, Hunter, contrary to original plans, soon had to use large numbers of troops.48
Construction Corps of the Philippines
Although Sverdrup had considered organizing a number of additional subordinate commands, only one more was formed—the Construction Corps of the Philippines (CONCOR), organized to make further use of Filipino workmen. It was set up on 25 April, under Col. Samuel N. Karrick, to undertake reconstruction in the Philippines, especially in and near Manila. Workmen, recruited on a voluntary basis for a minimum period of six months, would be directed by American and Filipino officers. This type of organization was expected to make possible a more efficient use of the Filipinos by providing better organization and supervision and reducing labor turnover. The workmen were to be organized into labor battalions. At full strength, each would have 92 officers and enlisted men from the U.S. Army, the Philippine Army, and the Philippine Scouts, and 1,037 civilians. A CONCOR battalion had a special table of organization and equipment closely resembling that of the former Civilian Conservation Corps battalions in the United States. Recruitment was slow, and by I June, CONCOR had only one battalion. Thereafter, expansion was more rapid, four battalions being activated in June. Including both skilled and unskilled workers, the battalions became quite efficient in all types of construction, except possibly those requiring much earth moving. They built barracks, warehouses, and hospitals, and maintained roads and utilities. Labor turnover was of serious concern at first but became less so as the organization was improved. Though wages were low, many Filipinos were attracted to the organization mainly because it provided meals at cost and permitted employees to buy scarce articles in the Army’s post exchanges.49
Changes in ENCOM
In the rapidly changing conditions in the Philippines, Sverdrup’s staff, and his subordinate commands as well, underwent almost continuous modification. During the first months the number of men in ENCOM headquarters fluctuated greatly. In June the War Department authorized a staff of 114 officers and 652 enlisted men. Meanwhile, Sverdrup found himself directing the construction efforts of a larger and larger engineer force. Late in April, he had acquired an additional unit. This was the Boat
Building Command, which had been established in mid-1944 at Milne Bay to direct the activities of the boat assembly units in the theater. In early 1945 the command was transferred to Batangas, Luzon, where the men rebuilt their assembly plants and were soon putting landing craft together again. The Luzon Engineer District also expanded rapidly, and by the end of April, Colonel Neilson had about 250 military and civilians on his staff. Within the next few weeks, he had some 30,000 engineer troops and over 20,000 Filipino civilians working on various projects. The General Engineer District likewise grew rapidly. When the Leyte Engineer District was inactivated in May, GENED took over its projects, and it took over LUZED’s when that organization was inactivated in July. By then, the General Engineer District had under its control most of the military construction in the USASOS area in the Philippines.50
The type of construction organization that many engineers had wanted since the early days in Australia, one headed by an engineer officer, was now a reality. Nevertheless, many of the difficulties previously experienced were still prevalent, undoubtedly because they were too basic to be easily eliminated by a change in organization. Shortages of men and supplies were still the rule, as were the problems generally encountered in coordinating a construction effort over a vast area in a short time. Some felt that ENCOM, directing work formerly handled well enough by base section and base commanders, was merely another headquarters that had to be dealt with. From the standpoint of many engineers, ENCOM had the great advantage that it was an engineer command. Engineer units of such a command were more likely to receive a sympathetic understanding of their problems than they could get from nonengineer base and base section commanders. ENCOM consequently improved the morale and efficiency of engineer units. It further raised morale by giving a number of promotions that could not be granted earlier because of limitations in the tables of organization.51
Army Forces, Western Pacific
On 7 June USASOS was redesignated Army Forces, Western Pacific (AFWESPAC) and placed under the command of Lt. Gen. Wilhelm D. Styer. Somewhat expanded in functions over its predecessor, AFWESPAC was to provide logistic support for U.S. Army troops in SWPA and AFPAC as directed by higher headquarters. On 10 June, General Worsham, formerly division engineer of the Northwest Service Command in Canada and Alaska, became Engineer, AFWESPAC. His staff was one of considerable size, by the end of June consisting of 144 officers, 435 enlisted men, and 33 civilians—a total of 612. AFWESPAC had more than zoo engineer units numbering about 65,000 men, and within a month the figure had risen to 90,000. Engineers made up
one-fourth of all the troops under AFWESPAC’s command. Worsham’s staff was before long concerned primarily with the construction and maintenance of bases needed to support the invasion of Japan and with making plans and preparations to furnish the engineer troops and supplies required for that assault.52
Construction in the Philippines
Rehabilitation and construction in the Philippines surpassed anything hitherto attempted by the engineers in the Pacific in a comparable period of time. Airfields had high priority and twenty on Luzon were repaired, improved, or newly constructed during the first six months of 1945. One of the fields which received a great deal of attention was Clark. The engineers first put the two existing runways in temporary operating condition and then began work on two new 7,000-foot runways for bombers. At Porac, eight miles south of Clark and at Floridablanca (formerly Del Carmen), four miles still farther south, they put in new strips for bombers, also. A great deal of effort was necessary to rehabilitate Nichols and Nielson Fields in the Manila area and to provide them with additional facilities such as gasoline storage and hangars. Most other runways on Luzon, rehabilitated or constructed to meet current operational requirements, were not developed to any great extent. The engineers did rather extensive work on a number of fields in the southern Philippines. The one at Puerto Princesa, Palawan, was rebuilt and lengthened to 7,000 feet; on Mindanao, the fields at Zamboanga and Malabang were improved and enlarged; two all-weather fields were built on Mindoro; four were developed in the Visayas. All told, the engineers rehabilitated and newly constructed forty-five runways in the Philippines during the first six months of 1945.53
The engineers generally provided new facilities for storing gasoline. At the same time they constructed or rehabilitated fueling jetties and laid more than 500 miles of pipeline. One of the major new storage installations was the large tanker terminal near Mariveles on Bataan, from which pipelines were extended to Clark and nearby airfields; construction progressed rapidly during the spring of 1945, despite unfavorable weather. Before the battle for Luzon ended, storage for 160,000 barrels had been erected at Mariveles and over fifty miles of 6-inch pipeline installed, with aviation gasoline flowing through the line at the rate of 412 barrels an hour. The 40,000-barrel welded steel tanks at Mariveles, the first of which were completed in August 1945, were the largest storage tanks of this type erected in the Southwest Pacific.
In an extensive hospital building program, major installations were erected at Manila, San Fernando in northern Luzon, and Batangas in southern Luzon. One of the largest projects, built on the
site of a Japanese airfield in the Mandaluyong area in southeastern Manila, was the first in SWPA to use prefabricated steel units. The main members were prefabricated; an assembly line was used to preassemble wall panels, floor joists, roof girders, and posts. The steel units, made of special lightweight metal, were 20 feet wide and varied in length from 48 to 240 feet. The floors were made of plywood, the walls and ceilings of beaver-board, the windows of plastic. Some of these units were also erected at Fort McKinley Hospital. The steel units could be dismantled and then re-erected with only a 5-percent loss of material, but re-erection required considerably more effort than putting up the wooden ones.
Warehousing was extensive. Most storage was in the Greater Manila area, where the engineers supplied about 9 million square feet of covered storage and some 34 million square feet of open storage. They made about 2 million square feet of covered storage available by rehabilitating existing buildings. One of the largest projects was the quartermaster depot built on the site of the old Zablan Airfield, just east of the capital. It consisted of 31 prefabricated buildings, each of which, measuring 10 by 405 feet, covered slightly more than an acre, and took about a week to erect. Floors were of steel mat, wood, concrete, or crushed stone, depending upon the type of supplies to be stored. Bases M and R also had fairly large storage facilities.
Port areas had been severely damaged, especially at Manila, where the Japanese had systematically destroyed the prewar berthing facilities, particularly those of South Harbor; none were usable when the Americans captured the dock area. The harbor was cluttered with some 600 sunken vessels. Reconstruction and clearing began on March. Floating ponton piers were again invaluable and the engineers used them extensively at first to provide facilities rapidly, but since these piers required a great deal of maintenance and could be used successfully only in well-protected harbors, the engineers rehabilitated existing facilities and undertook some new construction. They built two new fixed piers, which provided eight additional berths in South Harbor, and lengthened two existing piers. Pier 13 (formerly Pier 7), one of the longest covered piers in the world, was rehabilitated with the help of about 1,800 troops and 2,000 civilians and provided berths for six Libertys. During the reconstruction period, five Army dredges excavated 3,250,000 cubic yards of material from North and South Harbors and the Pasig River. The Navy, meanwhile, was clearing a path through the wreckage in Manila Bay. The port was made serviceable in a relatively short time, the first Liberty docking on 17 March. The engineers, also did harbor work at San Fernando, Subic Bay, Mariveles, Puerto Princesa, Zamboanga, and Cebu City.
Along with the reconstruction of Manila Harbor, a major undertaking was the rehabilitation of the city itself. Engineer construction units under ENCOM took over this work from Colonel Liles’s command in March. One of the first jobs to be completed was the restoration of the water supply system. With the capture of Ipo and Montalban Dams, the prewar water pressure in north Manila was restored. By putting a 16-inch water main across the Pasig at Ayala Bridge, the engineers
partly restored water service in south Manila. They were at the same time repairing the sewerage system, which was expected to be turned over to the civilian authorities in the fall. The electric power system had been so badly damaged that large-scale reconstruction was necessary. Power resources remained low; for a time a destroyer escort in Manila Harbor was fitted up to provide 3,500 kilowatts for the city. Work on the electric plant and power lines was a time-consuming job. The engineers cleared and repaired about ninety miles of streets. They put temporary bridges across the Pasig to replace the five destroyed during the fighting. They pulled 200 sunken boats out of the harbor. In short, Manila was again made habitable.
Engineer units did much additional construction in various parts of the islands. They provided staging areas for 350,000 troops and replacement depots and disposition centers for 125,000. They successfully carried out railroad rehabilitation, and by 11 March service was restored on the Manila Railroad from Lingayen Gulf to the capital. An engineer combat battalion with the 158th RCT placed sixty-five miles of the railroad on the Bicol Peninsula in operation. Other engineer efforts included quick repair of seventy-four miles of railroad on Panay and a short stretch on Cebu, and attempts to speed up rehabilitation of sawmills and cement plants.
Construction on Okinawa
The organization established on Okinawa for construction was similar to those set up on other islands of the central Pacific. An island command, in Army terms a garrison force, was organized and made responsible for the construction of the base and airfields and for the supply of combat and garrison troops. The island commander on Okinawa was Maj. Gen. Fred C. Wallace. His engineer, a naval officer, was responsible for construction for the Army and the Navy; an Army engineer, with the rank of colonel, was deputy engineer. The Engineer Section was staffed with officers and men from the 1181st Construction Group and from the Naval Construction Office, Tenth Army. Under the command of the island engineer were Army engineer units and naval construction battalions, which were to build the Army’s and Navy’s projects, respectively. Constructing units, assigned to the Island Command and scheduled for early landings on Okinawa, were attached to XXIV Corps and III Amphibious Corps. The first engineer units of the Island Command landed on D-Day. Within the first month, nineteen Army engineer units and naval construction battalions had come in; more arrived in May and June. In late May 16,000 tons of construction materials arrived for the Navy—the first large shipment of such supplies to reach the island. The first large shipment for the Army was unloaded late in June. The slow arrival of supplies, partly caused by the bitter Japanese resistance, delayed airfield and base construction. The unexpectedly tenacious resistance also meant that some of the engineer construction units had to be diverted to army and corps to provide engineer support. Tactical operations within the Island Command area itself involved mainly elimination of snipers and skirmishes with small enemy groups. The
Island Command’s area of responsibility was gradually increased until by 30 June 1945 it included all of Okinawa.54
As indicated earlier, the construction planned for the island was tremendous. Six runways for B-29’s were to be built, the most extensive airfield complex ever designed for an island in the central Pacific. The initial program was not only frequently revised, but also expanded. Early in January 1945 General Buckner had directed that an airfield be built on Ie Shima and that additional base facilities be constructed on small islands near Okinawa. After operations on Okinawa were under way, reconnaissance indicated that there were several additional good sites for B-29 runways. After a conference of major echelon representatives in early May 1945, Nimitz directed that B-29 fields be constructed on Okinawa only; construction on Ie Shima was to be limited to a field for fighters. Plans now called for 6 Army airfields on Okinawa, but only three of them for B-29’s. Later, additional fields were required to take care of units of Far East Air Forces which were to be transferred to Okinawa, and, still later, additional facilities were needed for the Strategic Air Forces. By 30 June 22 runways on 13 airfields had been proposed and suitable sites found on Okinawa and Ie Shima; this revised airfield program meant that Army facilities had to be provided for 450,000 men.55
Construction of airfields had begun on 3 April with the rehabilitation of Yontan and Kadena. Both fields had been taken almost intact; such damage as was found had been largely caused by American bombings. Within a few days, both fields were ready to take fighters. At Yontan, working from 30 April to 30 June, engineer units under Island Command put in the first American-built runway on Okinawa—a 7,000-foot medium bomber strip. The first B-29 runway was constructed at Kadena and was about 25 percent complete by the end of June. At Bolo Airfield on the western shore of the island, another B-29 runway was under construction and still another B-29 runway was being developed at Futema. On the whole, construction of bomber and fighter runways was progressing satisfactorily until heavy rains in late May and early June slowed down the work. Then much equipment had to be diverted to tactical units to keep supply routes open to the front. Ie Shima was being transformed into a giant airfield. After the enemy runways had been rehabilitated, construction of new ones began, but progress here was hampered by the large number of mines which the Japanese had placed in the airfield area. Because the runways occupied almost the entire island, the civilian population was evacuated. By mid-May, runways, taxiways, and hard-stands on Ie Shima were fully operational. By the end of June, five airfields on Okinawa and Ie Shima were operational, and six additional ones were being rehabilitated or newly constructed.56
Airfield Construction, Iwo Jima
Much other work was undertaken. Repair of existing roads and construction of new ones was vital. By midyear the engineers had built supply roads along both the east and the west coast, as well as down the center. Most of the important thoroughfares were developed to take two-lane traffic. By 30 June 340 miles of all classes of roads were being maintained, 40 miles of the total having been newly constructed. The situation was at its worst during the heavy rains of late May and early June. At one time only one supply road to the front lines was open. The development of harbor facilities began on 30 April with the construction of a 500-foot ponton cube pier for barges at Buckner (Nakagusuku) Bay. By 30 June six temporary ponton piers to take barges were in place, and preparations were well along on the second phase of port development—the construction of permanent piers. Of high priority was the construction of storage tanks for gasoline, the laying of pipelines, and the installation of pumping systems to get the gasoline from the tankers to the airfields. By 25 April gasoline was being pumped through pipelines to Yontan and Kadena; by the end of June tank farms had been erected at the major airfields
then in operation. The building of camps and hospitals was delayed because of the priority of combat and air force construction.57
Construction on Iwo Jima
The main reason for taking Iwo Jima had been its importance as an air base site. This volcanic island presented some unusual problems in airfield construction. The fields had to be built on volcanic ash, and a major puzzle was how to bind the hot asphalt mix to the ash. The engineers developed a procedure that proved to be successful. They put down a layer of crushed stone two inches thick and thoroughly rolled it into the ash. When the ash was wet after a rain, it settled, leaving the stones slightly exposed, so that the resultant mixture adhered to the 2-inch asphalt surface. This method was also successfully used in building roads on the island.
A strip of especially hot ground, about 400 feet wide, ran under the runways of the B-29 field and one of the fighter fields. The strip appeared to have the same bearing capabilities as the cooler ground, but after the surfacing had been in place for several weeks, soft areas developed and the runway cracked. The ash underneath had become saturated with water produced by the condensation of the steam trapped by the asphalt surface. The men checked this condition by excavating about sixteen inches below the asphalt surface, filling in 2 to 6 inches of rock, and laying a new surface. As a further precaution, they left breathers at the edge of the stone fill.
After a prolonged rainy period, parts of the asphalt surface of one of the fighter strips became inflated and steam began puffing out. The engineers dug trenches from the side of the runway to the steam vents and laid pipes in them to carry off the steam, which could thereafter be seen hissing at the sides of the runway. They sometimes treated a bulging asphalt surface by driving perforated 1-inch pipes through it, leaving the ends flush with the surface. This expedient solved the problem until the heat caused the asphalt to disintegrate to powder. When that happened, the engineers put down another 1-inch layer of hot-mix asphalt and drove more vent pipes. Little had to be done about drainage because of the porous nature of the volcanic ash.
The construction of storage for aviation gasoline presented the problem of how to reduce the temperature of gasoline standing in the miles of pipe in the hot, volcanic ash—pipes that had to be put underground to get them clear of runways and taxiways. The engineers did not have the time or the materials to provide insulation. In its heated state, sometimes as much as 170° F., the gasoline could not be pumped into the planes. Before the planes could be refueled, the engineers had to erect spare storage tanks into which the gasoline could be pumped about an hour before takeoff. Only in this way could adequate amounts of fuel be cooled. “It was profoundly inspiring,” Col. D. A. Morris, engineer of the garrison force on Iwo Jima wrote, “... to see hundreds of these mighty bombers coming in to land
or to see two mile-long columns of them … lined up for refueling.”58
Construction in Hawaii
In 1945 General Richardson, commander of USAFPOA, still had many projects to carry out in Hawaii—the completion of seacoast defenses; further development of the port of Honolulu; construction of additional office space for army headquarters; improvement of some of the airfields, particularly Hickam and John Rodgers; the furnishing of housing for approximately 5,000 civilian employees; and the construction of rest and recreational facilities. Many of the projects entailed new construction; others, rehabilitation of old facilities. The most important jobs were the completion of facilities for the Air Forces, Signal Corps, and Ordnance, the building of recreational facilities for the troops, and the construction of the new Tripler General Hospital. Probably the project that had been under way longest of all was the installation of the naval guns from damaged warships. The delay was still mainly due to the great amount of time required to manufacture the many necessary specialized parts, as well as to the lack of two especially important items—the turning gear worm and pinion. The scarcity of technicians forced the Navy to institute a special training program on battleships and in Navy shops. The guns would not be finished in time to be of service during the war. Battery Pennsylvania was expected to be completed by September 1945; Battery Arizona, by the end of the year.59
The South Pacific
There was little activity in the south Pacific by 1945. Construction had ceased, and on t December 1944 South Pacific Base Command had directed that all work except that of an emergency nature or necessary to maintain installations be stopped. Engineer units were continuing to move to the central and southwest Pacific. Those still in the area were, for the most part, on New Caledonia, Guadalcanal, and Bougainville and belonged mainly to supply and maintenance units. The roll-up of bases, under way since mid-1944, was accelerated. Efate and Tongatabu were closed out in May 1945. By July, New Zealand was closed out except for a few personnel. It was planned to have New Caledonia serve as the final storage area and transshipment point for the south Pacific. As of midyear, base facilities on that island were still extensive. In June the Engineer Section of the South Pacific Base Command at Noumea still had 11 officers and 84 enlisted men, whose main job it was to supervise the dismantling and disposal of facilities. A most important part of their task was the return of real estate to the owners—about 85 percent of all leases in the theater were for property on New Caledonia.
The number of troops continued to decline. The base command had some 13,000 engineers in January; the number was down to 1,072 by mid-August.60
Declining CBI
In Burma and China, engineer work was still considerable, for in early 1945 there was a possibility that fairly extensive operations would be undertaken against the Japanese on the Asian mainland. The military outlook became more favorable in the first months of the year. With the capture of Lashio by the Chinese on 7 March, all of northern Burma was free, and British and Indian troops continued their advance southward. The Chinese armies in Burma began to return to their homeland for a showdown with the Japanese; Wedemeyer hoped to strengthen them sufficiently to enable them to fight their way to the coast by fall. The India-Burma Theater, under Lt. Gen. Daniel I. Sultan, would for all practical purposes function as a communications zone. Major jobs for the engineers on the Asian continent were building additional airfields in China, improving the Ledo and Burma Roads, and completing the system of pipelines. As the war progressed, it became apparent that decisive operations would not take place in China. In the last months of the war, therefore, engineer work was largely of a routine nature.61
The logistical buildup in support of the China Theater would be of little avail if the Chinese armies proved too weak to drive the Japanese back. Wedemeyer detailed additional American instructors and liaison officers to Chinese armies and divisions as training activities were stepped up. Meanwhile, Chennault’s engineers continued work on a growing number of airfields to replace the eastern ones overrun by the enemy after August 1944. Resident engineers supervised the building or improving of nine fields east of Kunming and seven more north of the Yangtze River and east of Chungking. When fighting broke out between the Japanese and the Chinese in April, Chennault’s airmen controlled the skies. In May the Japanese began a general withdrawal, preparatory to the evacuation of southern China. As the Chinese moved eastward in June and July, they recaptured several of Chennault’s airfields which the Japanese had demolished. With the recapture of Liuchow at the end of June, Chennault flew in a detachment of the 930th Aviation Regiment to take charge of restoring the heavy bomber field there.62 At the same time, the engineers were increasingly engaged on a program of road improvement in southern China. Late in April Wedemeyer directed the Burma Road engineers to help their
Chinese Army counterparts rehabilitate roads in the Anshun–Kweiyang area, and in June SOS, China Theater, detailed the 1880th Aviation Battalion to help improve the 600-mile post road from Kunming eastward to Chihchiang. In June, also, the 858th Aviation Battalion and the 71st Light Ponton Company arrived from Burma to help the Yunnan-Burma Highway Administration improve the Burma Road. Meanwhile, the 191st Light Ponton Company took up ferry operations 260 miles east of Kunming.63
Work went ahead on the Ledo Road. It will be recalled that in August 1944 the War Department had authorized construction beyond Myitkyina of a one-lane paved road only. General Pick, convinced that continuous traffic could not be maintained over such a thoroughfare during the monsoon season, set out to widen the Ledo Road to two lanes throughout its length. When General Farrell sounded out the War Department in Washington in January 1945, he learned that the Operations Division would not object to widening the road after all. Somervell started procurement of additional H-20 bridges to make possible two-way traffic beyond Myitkyina.64 Work progressed, but slowly. Early in April, Lt. Col. W. S. Chapin, of Headquarters, Construction Service, after a personal inspection of the road, wrote Colonel Welling: “The highway from Myitkyina to Bhamo is now two track. A considerable portion ... from Bhamo to Namhkan is two track and the remaining portion between Namhkan and Wanting is also two track. By 15 June a two track all-weather highway will exist between Ledo and Wanting.”65
The most spectacular feature of construction on the road in 1945 was the erection of a number of bridges, particularly those over the Irrawaddy, Taping, and Shweli. Pick planned to build a combination bridge over the Irrawaddy to replace the ponton bridge at Myitkyina completed in early December 1944. The new bridge was to be erected some 20 miles downstream from Myitkyina at a point where the river was about 60 feet deep during low water and rose as much as 40 feet during floods. Pick decided to use H-20 girders resting on steel barges to form an 850-foot long center span. Timber trestles would be used for the approaches. The barges, knocked down, were already in the theater, having been sent from the United States to transport gasoline and other supplies on the Brahmaputra. The steel parts for the center span, on order from the United States, were not expected before the end of March, by which time the Irrawaddy would be in flood stage. The only feasible solution was to fabricate steel parts from such scrap metal as could be found in Advance Section. In mid-January 1945 the race against the flood waters began. To assemble and launch the barges, the engineers set up a marine ways on the river a short distance upstream from the bridge site; at the same time, they manufactured on the spot the vital steel parts
needed. On 31 March, about 75 days after work began and two months before the special bridging material arrived from the United States, the bridge was across the Irrawaddy. At its center it had 6 floating spans resting on steel barges, with a distance of about 10 feet between barges. On either side of the floating section were double-hinged spans, each 225 feet long, which permitted the center section to rise and fall with the level of the river. Designed to take a water fluctuation of 40 feet, the two hinged sections were attached to fixed trestles near the banks. This bridge, two lane, had a capacity of 35 tons, and with its approaches was 1,620 feet long.66
Beyond the Irrawaddy, all major bridges were Baileys. In view of the difficulties of getting H-20 bridges from the United States, General Farrell in late 1944 had arranged with the British for the procurement of Baileys. The parts had been moved up the Ledo Road in late 1944 and early 1945. In February Company A of the 209th Combat Battalion completed a 400-foot Bailey over the Taping. By 1 March Company B of the 209th had built a similar structure, 450 feet long, across the Shweli.
On 21 May General Pick, then in Washington, announced the formal completion of the Ledo Road. Typical of the congratulations he received was the one from Covell, stating that the Ledo Road would “... stand forever as a monument to the unstinting labor, courage, determination and ingenuity of both the living and those who gave their lives in
this remarkable accomplishment.”67 But after it was finished the road had far less strategic importance than in the early days of its construction. By 1945 the War Department was no longer interested in the tonnage goals set up at Quebec in August 1943. The Department now directed one-way deliveries of vehicles and munitions only. No more than eighty-eight truck companies would be provided for all operations on the road. To hold the thoroughfare open during the monsoon of 1945, Pick kept 12,000 engineers busy resurfacing the roadway, improving drainage, and repairing bridges.68
The plans made at the QUADRANT Conference for the construction of three pipelines to China were cut drastically. On 18 January Pick directed Colonel Morse to complete the 6-inch standard-weight line from Tinsukia as far as Myitkyina. This job was to be finished by 15 July. The 709th and 1382nd Petroleum Distribution Companies, reinforced by the 1304th Construction Battalion and elements of four general service regiments, began work on 16 February with pipe supplied by British depots. Sultan, complying with Wedemeyer’s request made in mid-April, agreed to stop work on the 6-inch line at
Three examples of bridging in the CBI. Above, the steel barge bridge across the Irrawaddy, with a temporary ponton bridge in the foreground. Below, the Bailey suspension over the Taping River
Myitkyina and turn over to the Chinese theater the cargo space thereby released. Morse pushed his various projects to completion. On 7 June the first gasoline reached Kunming through the 928- mile 4-inch line, and nine days later the 6-inch line from Tinsukia to Myitkyina was complete. Twelve of the seventeen pipeline companies in the two Asian theaters were thereafter engaged in pumping and maintaining the lines from Assam to Yunnan.69
Although the pipelines built were not as extensive as had been originally planned they still made up the greatest military pipeline system in history. (Map 32) Counting the spur lines from Calcutta to the B-29 field in West Bengal and the lines from Kunming to the airfields in Yunnan, the engineers had built, in India, Burma, and China, a continuous pipeline system, with some 3,300 miles of pipe and 148 pumping stations. During the last two years of the war, engineer troops operating this enormous network handled over 15,600,000 barrels of gasoline and diesel oil. Most of this fuel was consumed either in port activities at Calcutta or in aerial operations from B-29 bases in West Bengal or at the transport fields in Assam. The two 6-inch lines delivered some 3,600,000 barrels to the Tinsukia tank farm. From there, about 2,600,000 barrels went to various points along the Ledo Road and approximately 462,000 barrels to points inside China.70
By mid-1945, the engineers in India were putting an increasing effort into the maintenance of airfields and the construction of warehouses at various fields supporting the airlift to China. And this drive was paying off. The Air Transport Command delivered more than 70,000 tons of supplies to Chinese fields in July 1945. More and more, engineer units were moving on to China, where they were sorely needed to assist in training Chinese engineers, restoring the eastern airfields, improving the Burma Road, holding open the roads, and operating ferries in the wake of the Chinese advance toward the coast.71
Maps
Supplying the great quantities of maps of the target areas needed for an attack on the Japanese home islands was the responsibility of the engineers of the Southwest Pacific and the Pacific Ocean Areas, the two theaters charged with the final assault on Japan. When AFPAC was formed, in April 1945, the number of mapping units in the Pacific was fairly adequate for the amount of work to be done at that time. In the Southwest Pacific, the mapping organization had reached a strength of approximately 6,000 men. All tactical units had their normal complement of topographic troops, except Eighth Army, which had only a corps topographic company. From mid-February to mid-April, the 648th Topographic Battalion, together with its base map plant, moved from Melbourne to Manila. The battalion was installed
Map 32: Pipelines in CBI
in the Aguinaldo Building in downtown Manila in space formerly occupied by a department store. Production of maps resumed full speed early in June. The map depot detachments had been moving to the Philippines as rapidly as the situation permitted.
The 30th Base Topographic Battalion, which had arrived in Hawaii in January 1945, had been put in the huge three-story underground structure originally intended for the Hawaiian Air Depot. The underground chambers, completely air-conditioned and fluorescent lighted, were well suited for the work of the topographic battalion.72
With the mapping of the Japanese home islands assuming greater and greater importance after the formation of AFPAC, more mapping units were needed from the United States. MacArthur requested that the 29th Topographic Battalion be sent to the Philippines. Stationed at Portland, Oregon, the 29th had helped on a number of long-range projects for both the Pacific and European theaters. MacArthur’s request was granted and the unit was scheduled to arrive in Manila in July.73
Late in 1944 seven geologists from the
U.S. Geological Survey had arrived in Honolulu, their job to prepare terrain studies of areas in the Pacific likely to come under attack. Their assignments were similar to those of the teams of geologists who had gone to the Southwest Pacific earlier that year. Responsible to Brig. Gen. Herbert B. Loper, the Engineering and Terrain Intelligence Team, as the group was called, prepared studies as needed by tactical commanders. The first request was for data on the beaches and offshore conditions on Iwo Jima. In preparation for the Okinawa Campaign, about twenty-five studies were prepared for Tenth Army. Thereafter the intelligence team devoted its efforts mainly to gathering information on the terrain of southern Kyushu, one of the Japanese home islands. Peak strength of the team was 13 and included 10 geologists, 2 soil scientists, and a highway engineer.74
Maps made before the war gave a fairly good coverage of Japan, but the need to bring them up to date was urgent. The most pressing need was to coordinate efforts of the photographic units which were bringing back aerial photographs of the Japanese home islands. Numerous sources were supplying. photography. The four main ones were squadrons of the Far East Air Forces, based in the Philippines; units of the Strategic Air Forces, which took off from the Marianas and Okinawa; Marine photographic squadrons, which likewise took off from the Marianas and Okinawa; and elements of the Fourteenth Air Force, operating from China. Among the lesser contributors were Navy fliers who obtained photographs while making strikes against the Japanese home islands. Lack of coordination among so many sources hampered efforts to secure adequate photographic coverage of Japan proper and to distribute the photographs promptly to the mapmaking units.
To improve this state of affairs, representatives of the various theaters and of agencies in the United States concerned with mapping held a conference in Hawaii in May. Among those represented were AFPAC, CINCPOA, the Army Air Forces, the Strategic Air Forces, the Office of the Chief of Engineers, and the Army Map Service. Agreements were reached on all important matters, including the areas of Japan to be mapped, the types of maps to be made, the scales to be used, and the priorities in which maps were to be produced. Specifications for aerial photographs were defined. Responsibilities for the compilation, reproduction, and distribution of maps were assigned. MacArthur was to have primary responsibility for the control and coordination of the mapping of the Japanese home islands, since he was to be primarily responsible for combat in any invasion. Coordination of mapping in the Southwest Pacific and the Pacific Ocean Areas was brought about by making Loper, engineer of USAFPOA, the head of Casey’s Intelligence Division.
Meanwhile, the mapping of the Japanese home islands was proceeding satisfactorily. By early June accurate maps of the four main islands, based largely on prewar material, were available. Revisions, based on aerial photography,
were required principally to show new works of man.75 The conferees in Hawaii had also apportioned the responsibilities of the terrain intelligence teams of the two theaters. The geologists in the central Pacific were to continue with their terrain studies of Kyushu, while those in the Southwest Pacific were to concentrate on studies of Honshu.
In a fast-moving campaign, such as was being undertaken in the Southwest Pacific, map distribution was a most difficult task. During the operations on Luzon, the map depot detachments could not keep up with requirements, even with the additional personnel supplied by replacement depots and labor pools. Topographic supply was improved. During the New Guinea Campaign, a topographic supply depot, consisting of one officer and twelve enlisted men, had been installed on a barge. The barge, of reinforced concrete, arrived in Manila in the spring of 1945, and was used to supply maps to units engaged in combat in the outlying parts of the archipelago.76
Supply in the Pacific
The engineers of the Southwest Pacific and the Central Pacific were also the ones with the most pressing supply problems in the last months of the war and would be the ones mainly responsible for adequate engineer supply in the planned
invasion. Engineer supply, usually in a rather precarious state, showed signs of improvement in the closing months of the war, but many of the basic problems remained. In some respects there was a trend for the better in the Southwest Pacific, both in the combat zone and in the rear areas. Engineer supply in support of combat, far from satisfactory on Leyte because of the impromptu nature of that operation, was adequate during the remainder of the Philippine campaign. At least in part, this improvement resulted from the fact that the organization for supply was better than for most earlier operations. In the central and southern Philippines, Eighth Army engineers sometimes found supply not very satisfactory, but needs were not so great.
The move to the Philippines inevitably caused a certain amount of dislocation in supply. With the inactivation of the Distribution Division in February 1945, responsibility for stock control was transferred to Luzon Base Section, and later, Philippine Base Section. After ENCOM was established in March, most of the engineer units assigned to bases in the Philippines were engaged in supply work. As construction in the Philippines expanded, difficulties in supply again became conspicuous. Once more in evidence were insufficient long-range planning, poor stock control, careless unloading and storage, especially at the ports, the misuse of supply units, and the inadequate supply training of many officers and men. To provide more efficient supervision of supply, the War Department had organized depot groups which would direct supply more or less as construction groups directed
construction.77 Interest in depot groups was not strong, and few engineers seemed to be aware of their value. “As I have said several times,” General Ross wrote to Sverdrup on 19 February, “I am still of the opinion that the Corps of Engineers is not yet supply minded. ... The need for construction groups, brigades ... and other supervisory groups is well recognized and pushed ... the need for supply supervisory groups is even more necessary. ...”78
The distribution of spare parts improved during the Philippine campaign, due partly to the arrival of larger quantities from the United States and partly to better distribution in the theater. To facilitate distribution to units in forward areas, the engineers used ships stocked with spare parts and known as “floating depots.” A Liberty ship, the Robert Louis Stevenson, the first floating depot to be used by the engineers, was ready in time for the Leyte operation. Three of the holds were assigned to the engineers and two to ordnance. Bins between the decks of the three hatches held loose items and boxed spare parts were stored in the holds. Since there had been little time for remodeling, certain deficiencies were more or less to be expected. There was no ventilating system between decks and no stairwell between the top deck and the section of the ship where the binned parts were kept. All parts had to be handled by ships tackle or an improvised A-frame with block and tackle.79 A second vessel, the Armand Considere, a concrete steamship operated by civilians, helped supply Eighth Army engineer units in the southern Philippines. Spare parts were also shipped by air.80 Two marine spare parts depots were opened—one in Tacloban and another in Manila. The “floating warehouse” system was also used for marine parts. A barge, the Douglas Fir, operated by a crew of men from the 2nd Special Brigade, supplied spare parts to amphibian units.81
The maintenance of equipment improved considerably during the Philippine campaign, mainly because the number of maintenance companies was increased. An engineer “service center” was opened in Manila, where a number of heavy shop and maintenance companies were installed and given the job of putting equipment back in shape. To facilitate repair in the forward areas during operations in the Philippines, a heavy shop company was installed on a concrete barge and did fifth echelon maintenance.82
In the central Pacific, most of the difficulties that had plagued the engineers in 1944 continued on into 1945. Although the quantity of stocks arriving from the United States increased, problems of distribution remained. Still all too common, especially in the forward areas, were the shortage of trained personnel and inadequate stock control.
An engineer officer making an inspection of supply depots on the islands of the western Pacific early in 1945 reported “... a rather dismal situation in the forward areas insofar as Engineer stock control and depot operations are concerned.” He felt the trouble in large part resulted from “inadequate trained personnel and lack of preplanning.” The inexperienced men handling the large quantities of supplies in the depots could not even tell what many of the items they had on hand were used for, which in itself helps to explain why stock control was faulty and distribution inefficient. The supply of spare parts was inadequate and the numerous problems in obtaining and distributing them continued until the end of the war.83
Training
During the Philippine campaign, engineer training had further been put to the test. As in New Guinea, training for combat was on the whole adequate, but still a number of senior engineer officers thought certain changes in emphasis would be desirable. They believed more stress should be placed on map reading and the interpretation of aerial photography, and on placing mines and booby traps, as well as on detecting those of the enemy. They also held that, in view of the great importance of amphibious operations in the Southwest Pacific, more emphasis should be put on familiarizing the men with certain details of amphibious operations. With regard to the latter, it was believed especially desirable to teach the men how to recognize the different types of landing craft and to instruct selected personnel in how to waterproof vehicles and remove them from landing craft.
As before, training for construction and supply was noticeably deficient, and also as before, little time was available for additional instruction because of the pressure of work. Units of Sixth Army, Eighth Army, and USASOS carried on training in such subjects as construction operations, equipment maintenance, bridge erection, and mine removal, but the instruction was mainly refresher courses in subjects neglected or not required during the preceding years.84
Serious deficiencies in training on the part of many Engineer officers and men in planning and supervising construction and in operating and maintaining heavy equipment, made more and more apparent the need for some kind of central theater engineer school with a technical curriculum. Such a school would have to provide more advanced instruction than could be given in unit on-the-job training or in Australian or unit specialist schools. Casey and Sverdrup, especially, were interested in setting up such a school. Training experts estimated that to be adequate, the school should have approximately 70 officers and 350 enlisted men in attendance. An instructional, administrative, and housekeeping staff of about 50 officers and 180 enlisted men would be required. This requirement
would mean the withdrawal of men and equipment from active operations, but since the total would be less than percent, the effect on operations would be negligible. The chief engineer of USASOS and the engineers of Sixth and Eighth Armies and FEAF were not in favor of setting up the school because of the pressure of operational responsibilities. They felt it would-be preferable to continue the engineer schools already in progress and possibly expand further the Equipment Maintenance School already functioning at Base B as part of the USASOS specialist training center.85
General Casey’s office, however, began planning in late 1944 for a central theater school. The object was to organize the school in New Guinea as soon as possible and establish it in the Philippines, preferably near Manila. Organization proceeded slowly. A commandant was appointed who prepared a curriculum and obtained instructional material from the United States. By 15 March 1945 a tentative course of instruction had been worked out, and in July a site for the school was found at Clark Field, about fifty-five miles from Manila. Actual instruction did not begin until 3 September 1945. The engineer school was thus a long time in getting under way. The differences of opinion regarding the advisability of having the school, the difficulties in getting qualified instructors and suitable training equipment, and the shortage of facilities to transport the students to the school all had delayed its establishment.86
Planning for the Invasion of Japan
Preliminary Planning for Kyushu
Planning for the invasion of the Japanese home islands was first undertaken by the engineers of the Southwest Pacific late in 1944. On 12 December, General Whitlock, MacArthur’s G-4, asked Acting Chief Engineer Sverdrup for a preliminary estimate of engineer needs to support a force of more than 500,000 men who would land on Kyushu, southernmost of the four main islands of Japan. After the assault, the engineers would construct three bases on Kyushu to support subsequent operations in the Japanese home islands. No date was set for the assault.87
At that time, the engineers had little information on Kyushu aside from what they could get from maps and the sketchy published data on hand. They therefore had to estimate their requirements from the size of the invasion force. The construction required would be the most extensive for any operation in the Pacific so far. Estimates, prepared in about a week, called for eleven runways to support thirty air groups. Exact information on Japanese airfields on southern Kyushu was lacking; the assumption was that existing fields would be almost completely destroyed and that new construction would amount to approximately 90 percent of the total. Two 4,000-foot dry-weather strips for fighters could probably be provided from existing fields in three days; three 6,000-foot
runways for six groups of aircraft, by the end of two weeks. Storage for 576,000 barrels of aviation gasoline could probably be readied in four months. Estimates were that repair and improvement of some 500 miles of roads would be necessary. A port capacity of between 500,000 and 600,000 long tons a month would probably be needed, with port facilities consisting of either wharves or lighter jetties. Widespread destruction would result if the Japanese made their usual suicidal stand; probably few supplies would be available locally and great quantities would have to be shipped in. Perhaps zo percent of needs could be procured in Japan. USASOS would be responsible for logistic support and would use one or more service commands.88
Planning progressed slowly during the winter. On 17 February Casey, just returned to his post as MacArthur’s chief engineer, wrote General Whitlock that a terrain study of southern Kyushu was under way, with a view to determining general locations for facilities and the feasibility of construction. The task was difficult since no aerial photography was available and all conclusions had to be based on maps and published data, which, Casey stated, did not “... permit accurate location of existing installations or possible sites for construction, particularly with reference to airfields, of which a large number will be necessary. ...” Although a considerable number of airfields were reportedly in the area, many were believed to be too small to be expanded to the sizes necessary for American aircraft.89 It appeared that amphibious operations would be moderately difficult on the assault beaches tentatively scheduled for landings near the town of Kushikino on Kyushu’s western coast and near the town of Shibushi on Ariake Bay on the island’s southeastern coast. Extensive use of floating piers would probably be necessary at both places. Southern Kyushu had few good harbors. Casey recommended that the industrial city of Kagoshima, about 20 miles southeast of Kushikino, and at the head of Kagoshima Bay, be developed to provide a port capacity of about 6,500 long tons a day. Information on roads and railroads was meager, but it was believed the road net would be adequate if it could be maintained. The single-track railroad had many tunnels and would probably be blocked in many places.
Preliminary Planning for Honshu
Two days after reporting to General Whitlock on the engineers’ progress in planning for the invasion of Kyushu, Casey received a request for a similar estimate for requirements to support an assault against Honshu in the Tokyo-Yokohama area, the industrial heart of Japan. Tentative plans called for a landing at Sagami Bay, southwest of Tokyo, and on Honshu’s Pacific coast east of the capital. The attacking forces would advance northeastward and northwestward, isolate Tokyo, and then drive the Japanese armed forces to the outlying parts of the island, where they would
either have to surrender or be destroyed. The initial landing forces would include 12 infantry divisions, an armored division, and 3 airborne divisions, with g infantry divisions in reserve. No target date had been set for the assault.
The engineers spent approximately two months in preparing their estimates. The information they had regarding the Tokyo-Yokohama area was only slightly more adequate than that regarding southern Kyushu. Sagami Bay, on the basis of small-scale hydrographic charts, appeared to be quite shallow and could probably be used only by small landing craft. Casey believed the bay should be used only temporarily, for, with the capture of Yokohama and Tokyo, together with their ports and harbors, there would be adequate facilities for handling the required 40,000 long tons a day. Casey proposed to rehabilitate facilities and do minimum construction at the two cities to provide berths for forty-five Liberty ships. The rest of the cargo would be handled by smaller vessels and lighters. The Tokyo-Yokohama area had an extensive railroad system. Casey recommended that it be fully rehabilitated and be used to the maximum extent. The road net was not satisfactory, and, in view of the heavy traffic it would probably have to carry, would require considerable maintenance. Some fifty airfields existed in the Tokyo area, most of them fighter fields, few of which were near the coast. The area west of Tokyo and Yokohama appeared to have the greatest concentration of airfields and appeared to present the most favorable sites for additional ones. The information was too sketchy to permit pinpointing. The area to the east of Tokyo was expected to present a wide variety of drawbacks. It had relatively few roads and railroads, and rice paddies were numerous, which indicated that desirable sites for airfields would probably be hard to find. For a total assault force of somewhat over a million men, the engineer troops would number approximately 185,000. Combat engineer support, including three special brigades, would total some 98,000 men; service engineers, about 87,000.90
Planning Progress
During the spring, planning continued on both proposed operations, but to a far greater extent for the assault on Kyushu, which was given the code name OLYMPIC. Additional information on Kyushu became available and, at the same time, the scope of the operations was extended. The original 31-group air program was increased to 40 and later to 51 groups. Planning could now turn from the general to the specific. On 10 April, shortly after the Joint Chiefs issued their first study for the operation, General Whitlock held a conference to iron out problems of responsibility for logistic support within AFPAC. Casey had too small a planning staff to prepare the basic engineer logistic plan, but he reviewed plans of subordinate commands with regard to engineer matters. At his request, a conference was held on 2 April attended by representatives from Sixth Army, which had been designated to carry out the combat operations, and
by representatives from other interested agencies to coordinate engineer planning for the support of a force now grown to over 600,000 men. It was still impossible to set definite figures for the amount of engineer supplies and the number or type of engineer troops needed because the basic concept was still fluid.91 Casey and Sturgis, especially, had many problems to work out. A conference on 4 May was the first of many that month at which the engineers of AFPAC, USASOS, and Sixth Army met to coordinate their thinking on various aspects of OLYMPIC. Engineer troops would, as before, play important roles in combat support, but Casey and Sturgis now gave more thought to base development. At the three bases on Kyushu—one at Kagoshima, another at Shibushi, and a third at Miyazaki, on Kyushu’s eastern coast about 35 miles north of Shibushi—construction was to be limited to the minimum essential operating facilities, but the minimum tended to grow. Finding answers for various problems and fitting them into the whole picture continued to keep Casey and Sturgis busy.92
Planning for OLYMPIC reached its final stages in June. AFWESPAC submitted estimates of the various types of Equipment, materials, and supplies that would be needed for operations and the construction of the three bases. Preparations were made to order supplies and assemble them in the United States. On 14 June the War Department granted MacArthur’s request for four additional engineer construction brigades. Frequent conferences were held, sometimes to discuss general problems, sometimes a specific subject, such as the number of bridges needed for roads and railroads, or how extensively prefabricated buildings should be used. A list of engineer troops was made, only to be replaced by another, which, in turn, gave way to a third. On 12 June MacArthur held a conference on construction planning, at which Casey and Sturgis brought up numerous matters for discussion. The conferees reached agreement on several points, such as standards of construction, the loading and shipping of construction materials, phasing of arrival of ships, facilities to be provided, and the number and kinds of engineer troops. It was conceded that very little local labor would be available.93
Assault Directives for OLYMPIC
On 20 June MacArthur issued Operations Instructions No. for the OLYMPIC operation. In conjunction with the Pacific fleet, Sixth Army was to carry otAt the assault, using as its major components three Army corps—I, IX, and NI—together with the Marine V Amphibious Corps. The initial landings were to be made at Kushikino, Ariake Bay, and Miyazaki. (Map 33) The ground forces upon landing were to coordinate their operations and seize and occupy roughly one-third of Kyushu and establish bases there to support an attack on the “industrial
Map 33: Planned Attack on Japan
heart of Japan.” AFWESPAC was to furnish all supplies for Army units mounted from the Philippines; Army Forces Middle Pacific was to supply units mounted from the central Pacific area.94 AFWESPAC’s Logistic Instructions No.
for the OLYMPIC operation provided for the organization of an army service command from AFWESPAC personnel who would be transferred to Sixth Army and moved to Kyushu as soon as possible. The date for the operation was set for 1 November 1945.
Estimates called for a sizable engineer force to support OLYMPIC. The engineers were to number 117,570 out of a total assault force of 549,503 men, or about 21.4 percent of the total. Amphibian engineers, including the 2nd, 3rd, and 4th Special Brigades, and combat engineers would total approximately 50,159 men out of 252,150, or 20 percent of the total combat troops. Service and Air Forces engineers would total 67,408 men out of 297,353, or 22.6 percent of the
total service troops. These figures were exclusive of the marines.95
As far as the engineers were concerned, the most important part of the plan for OLYMPIC pertained to construction of the three bases. Kushikino, to support 400,000 men, was to be the largest. Here the engineers were to build berths for ten Liberty ships, storage for 205,000 barrels of gasoline, 220 miles of roads, 7,500,000 square feet of storage, three hospitals with 13,250 beds, and two all-weather runways. The second largest base was to be at Shibushi, to support 185,000 men; it would have similar but less extensive facilities. The third and smallest base was to be at Miyazaki, to support 135,000 men.96
Additional Planning for Honshu
Meanwhile, work was continuing on the plans for the invasion of Honshu, which had received the code name CORONET. A major problem was revising engineer estimates to keep pace with the changing concepts of the operation. In late June plans called for making two landings on the Honshu coast east of Tokyo on Y-day, one by an army, the other by at least two corps. A landing would be made at Sagami Bay thirty days later. For the engineers these changes meant that estimates regarding port construction and reconstruction would have to be revised. An initial attack on the
east coast would probably mean that Tokyo and Yokohama would be captured later—possibly not till ninety or more days after the first landing. This would mean that more extensive temporary port facilities would have to be built during the first days of the landing—two artificial harbors might even have to be constructed. With regard to the lines of communication, no great changes were anticipated. Probably only the phasing would have to be altered. The eastern highways and railroads would have to be rehabilitated first, but the effort required would probably not be so great initially because of the fewer roads and railroads east of Tokyo. A larger number of airfields would have to be built east of the capital, and construction problems there would probably be more complicated because of the many rice paddies. More storage would have to be provided in the eastern areas. The total engineer tonnages sent in would undoubtedly remain more or less the same, but the phasing of shipments would have to be radically changed. Three special brigades would take part in the CORONET operation.97
On 7 August Casey’s planners finished a preliminary draft of the Engineer annex to the CORONET operations instructions. Though estimates were not finalized, an idea of the vast scope of the contemplated program may be derived from a partial enumeration of the planned facilities. Eleven all-weather runways were to be completed in 3 months; 171 lighter berths, seven floating Liberty berths, and 7,800,000 square
feet of covered storage in 6 months; garrison camps for 500,000 men and hospitalization for 42,750 fixed beds in 5 months; plus camps for 475,000 replacements, POWs, and civilian internees, within an unspecified period. This construction would require 1,016,591 deadweight tons of supplies. The proportion of engineer troops required for the CORONET operation was roughly the same as that for OLYMPIC. Combat engineers, together with three ESBs, totaled 102,427 men out of 555,115 assault troops, or 18.5 percent of the total. Service and air force engineers totaled 133,769 out of 513,925, or 26.1 percent of the total. The overall figures were 2 3 6, 96 engineers out of 1,069,040 troops. Despite the extensive construction required, the underlying idea of CORONET differed from previous operations in the war against Japan. This was an operation to vanquish the enemy in the territory being invaded and was not designed to establish bases from which to conduct further operations.98
Planning for a Peaceful Occupation
Since late spring Allied leaders had felt there was a possibility of Japan’s surrender or collapse before an invasion of the home islands took place. On 14 June the Joint Chiefs had directed MacArthur to prepare a plan for the peaceful occupation of the country. On 25 July MacArthur issued his Basic Outline for the BLACKLIST Operations to Occupy Japan Proper and Korea After Surrender or Collapse. Overall planning for a peaceful occupation did not require a great deal of effort. It was based largely on the planning already prepared for the assault. Sixth Army would occupy roughly the western half of the Japanese homeland, including the islands of Kyushu and Shikoku and the western half of Honshu; Eighth Army would occupy eastern Honshu, Hokkaido, and the southern half of Sakhalin. Tenth Army was scheduled to occupy Korea. AFWESPAC and AFMIDPAC would provide the logistics.
For the engineers, BLACKLIST would not mean the immense amount of combat support or the construction effort that an armed assault would require, especially an assault against suicidal resistance. Construction would be limited. Existing facilities would be used as much as possible and local resources and labor employed to the maximum extent. On the whole, forces and projects were about the same as were being planned for the assault, but conditions for construction would be far easier.99
Meanwhile, the war was moving rapidly to an end. The Japanese position by the summer of 1945 was hopeless. On 6 August the first atomic bomb was dropped on Hiroshima. Two days later Russia declared war on Japan and began a rapid invasion of Manchuria. The next day a second atomic bomb was dropped, this time on Nagasaki. On to August the Japanese asked for peace. Five days later, fighting stopped. With the landing of American paratroops at
Atsugi airfield on 30 August, the occupation of the Japanese home islands began and the BLACKLIST plan went in effect. Three days later, the official surrender ceremony took place aboard the battleship Missouri in Tokyo Bay.
Conclusion
The long war against Japan was over. In few conflicts had military engineers played so important a role as in this one. Engineers of the United States Army had been active in an immense area. From the barren reaches of Alaska to the deserts of Australia, from remote islands of the South Pacific to China and India, they had furnished the engineer combat and logistic support necessary for victory. Thousands of miles from the United States, they had worked and fought in regions consisting for the most part of deserts, jungles, coral atolls, sub-arctic wastes, and isolated areas cut off from the outside world by lofty mountain chains. They had been an integral and vital part of a complex and far-flung organization.
The story of the engineers in World War II is one of greatly expanded activities and unprecedented growth. In 1939 the Corps had 12 units, 10 of them combat, 2 of them topographic. By mid-1940 the number of units had risen to 25, of which 18 were combat. By the time Japan surrendered, there were, in the Pacific alone, 700 units, totaling 235,764 men in an army of 1,458,911. Many of the new organizations were highly specialized and responsible for missions which new technological developments had made necessary. Alongside the traditional combat battalions and general service regiments were such units as special shop battalions, pipeline operating detachments, model-making detachments, foundry teams, photomapping teams, technical intelligence teams, dredge crews, and port construction and repair groups. But even with the great expansion in personnel and the multiplication of specialized units, there were never enough engineer troops. To do the great amount of work for which they were responsible, the engineers wherever possible used civilians as well as troops. Within the United States and its possessions they engaged contractors and recruited workmen. Overseas, foreign governments employed local contractors and furnished workmen to do the building for the U.S. Army behind the front lines, while the engineers furnished the technical supervision. In some areas natives, scarcely out of the stone age and little acquainted with modern civilization, helped build the facilities the Army needed.
The absence of modern industry in much of the world where the war with Japan ;vas fought, the vast extent of the theaters of operations, and the lack of long-range planning for a struggle in numerous overseas theaters greatly complicated the most important of all engineer tasks—construction. One of the most exasperating problems, particularly in the Southwest Pacific, was the shortage of building materials, a shortage arising from the inadequacy of such supplies in the United States, the shortage of shipping to overseas theaters, and the inadequate amounts of materials in the overseas theaters themselves. In an attempt to make up for deficiencies in the many theaters, the engineers had to use
materials locally available and resort extensively to improvising. Designs were simplified, and flimsier, though still adequate, types of construction were used. More efficient designs were developed for many kinds of installations—runways were not crossed but built in parallel, more suitable oil pumping machinery and pipelines were devised for the combat zones, and, to a greater extent, prefabricated buildings were used. Local materials, some of them little known before the war, were utilized to the greatest extent possible. Coral was a godsend on the islands of the Pacific and native-type thatched roof huts served many a useful purpose. In their battle to furnish the facilities the Army needed not the least of the Engineer tasks was to curb unnecessary and sometimes extravagant construction, which various elements of the Army, for one reason or another, insisted on having.
Of great importance was obtaining the cooperation of other organizations to accomplish the Engineer mission. In the Pacific Ocean Area, for example, a continuing problem was the coordination of Army engineer and Navy construction activities, a coordination, on the whole, successfully accomplished. Highly important, too, was winning the cooperation of the engineers of the Allied armies, a feat achieved with varying degrees of success. It was easiest to secure by far with the armed forces of the members of the British Commonwealth; more difficult, if the national backgrounds were quite different from the American. Of equally great importance was making the best possible use of the available civilian forces—particularly in rear areas, as, for example, Australia,
India, and Burma. This was sometimes a complex matter, calling for a good deal of ingenuity and a better than average understanding of the national background and character. Even with the great technological advances, men were still important; the success of the war effort depended on the cooperation of many millions.
The war was not fought without certain shortcomings, notably in organization, becoming manifest. A continual handicap was the shortage of units, especially in the combat areas, where civilians, even if available, could not be employed to bolster the work force. Shortages of troops existed everywhere, except on the Alcan Highway and possibly in the Hawaiian Islands, during the first two years of the conflict. They were particularly severe in the China–Burma–India theater and in the Southwest Pacific, where a number of engineers cited the continual shortage of troops as their greatest problem. Equally difficult was the getting of individual replacements to bring up to strength the depleted units in the overseas theaters. It was even harder to secure qualified, well-trained replacements. The big cry was for great numbers of well-qualified men and units—a goal difficult, if not impossible, of achievement in modern war.
Since the war against Japan was fought over a much larger area than had been anticipated and in regions where so much unexpected engineer work had to be done, it is hardly surprising that a “balanced” engineer force was seldom attained. There were sometimes too many units of one type and more often not enough of another; on the whole,
there were more than enough combat and camouflage units but far too few construction and supply units. This being the case, units were put on construction and supply jobs, even though not trained for or experienced in such work—this was especially true in the South and Southwest Pacific. A makeshift arrangement, it was the best one possible under the conditions, but did not make for efficient operations.
In a war of rapid movement over great expanses, particularly the kind being fought in the Southwest Pacific from Australia to the Philippines, various problems in organization arose, one of the most important being to achieve flexibility of organization. To provide such flexibility the group type of organization—exemplified by construction brigades, construction groups, and combat groups—was developed and used to an ever greater extent. Each type of group had a headquarters to which units were assigned for a particular task; upon completion of the task some units were transferred out and others were assigned for the next, and somewhat different, task. Such relatively large, stable, and unwieldy units as the general service regiments were not well suited for a war of movement on an extensive scale. In addition to the fluid group type of organization, which could be adapted to the work at hand, the Southwest Pacific made use of the army service commands designed to begin extensive construction and logistical support in the forward areas at any early date; here again service units were assigned to a large and flexible organization for work in a combat zone in accordance with needs.
A matter of continuing controversy in theaters where a great variety of work had to be done was how best to assign engineer units to the various commands; the problem was particularly difficult with regard to the aviation engineer battalions, considered theoretically a component part of the Army Air Forces. Engaged in vital construction as the aviation battalions were, it was sometimes debatable whether they should be assigned to the Air Forces exclusively or to other commands as needed, particularly the Services of Supply. The basic policy, on the whole, was that under emergency conditions, where there was much work with few troops to do it, all engineer units should be utilized and assigned as the theater commander thought best, regardless of the regulations automatically assigning certain types of units to certain commands. Another problem was whether to put engineer construction and supply activities in the field under base commanders and have the engineers exercise only technical supervision or whether to set up a separate engineer construction command as was done in the Southwest Pacific and in part of the China–Burma–India theater. Here a comparison of results appeared to be in-Conclusive. Having engineer construction and supply in the field carried on under the direction of base commanders seemed to be a satisfactory arrangement, provided such commanders had a broad understanding of their mission and gave adequate support to the construction effort. While a separate engineer command would assure adequate support to construction, it was sometimes difficult to coordinate the responsibilities of such a command with those of the base sections and combat elements.
A serious deficiency was the shortage of supplies and supply units. Even more serious was the lack of spare parts, especially for the hard-worked equipment. In the overseas theaters, a serious weakness was the lack of adequate distributing systems for supplies and spare parts, most keenly felt in the Southwest Pacific, where exceptionally large quantities were needed. Much time was lost within theaters in shipping and transshipping stocks. Enormous distances and changing tactical situations militated against setting up an efficient distribution system. Effective, theater-wide stock control was lacking almost everywhere, so that it was difficult to make really efficient use of even the little that was on hand. Two of the greatest needs were, first, personnel well trained in the stocking and distribution of supplies and spare parts, and second, a much larger number of well-stocked and well-managed supply and spare parts depots. A critical situation was made worse by the fact that many Engineer officers were indifferent to supply and seemingly not fully aware of its importance. Of all the problems facing the engineers, those of supply were probably the most serious.
As the war progressed, the inadequate training and insufficient engineering background of many officers and enlisted men, particularly those who entered the Army after Pearl Harbor, came more and more to the fore. Many officers did not have an adequate engineering background to prepare plans for construction, to devise proper methods for undertaking a project, or to supervise the work itself. Enlisted men were poorly trained with regard to many aspects of construction; most glaring, perhaps, was the deficient training in the operation of machinery. The officers themselves, all too often inexperienced in such matters, could not instruct the men of their own units in how a job should be done. Training for combat, generally, had been sound, but in the war in the Pacific, combat support, unexpectedly, did not have the overriding importance it had had in previous conflicts on which planning had been so largely based. Direct combat support had been the engineers’ traditional wartime mission; many engineer officers preferred it to other tasks, which partly explains their failure to appreciate the importance of the engineer “service” functions behind the combat zones.
All of these shortcomings might have had more serious consequences had the Japanese not been plagued by far greater deficiencies. Japan had gone to war with only a small part of its military forces assigned to the war against the United States and the British Commonwealth. Of the Japanese Army’s 51 divisions, 59 mixed brigades, and 1,500 first-line planes in December 1941, Imperial General Headquarters could spare only 11 divisions and 700 planes for operations in the Pacific.100 Large forces had to be maintained in China to hold the Chinese in check and sizable forces kept in Manchukuo and the home islands as a precaution against a possible Russian attack.
More serious than Japan’s shortage of troops was her scant industrial potential. In terms of population, Japan may have ranked as a great power, but in industrial
capacity she was roughly the equal of Belgium. The plan of the Japanese leaders was to wage a limited war. They did not propose to invade the American mainland or even the Hawaiian Islands. It was their intention to destroy the U.S. Fleet at Pearl Harbor, defeat the Allied forces in the western Pacific, get control of the islands there, and transform them into powerful defensive barriers. The Japanese hoped the Allies would not be able to break through the barriers, even after long and bitter fighting. A compromise peace would result. This might have been the course of the war had it not been for the overwhelming technological superiority of the United States, a superiority that became more marked as the conflict continued. The battleship, the aircraft carrier, the airplane, and the bulldozer made Japan’s defeat inevitable. Innumerable engineer after action reports stated that the terrain was more of an obstacle than the enemy. From the engineer standpoint, the war was as much a conquest of geography as of the Japanese.
Despite deficiencies, which were more or less unavoidable, the Engineer mission was successfully accomplished. The amount of work done was tremendous. That so much was done was in no small measure due to the courage and skill of all ranks. Morale was generally high; as in the rest of the Army, there was an overriding determination to defeat Japan. Officers and men alike worked long hours, made the best use of the resources at hand, and adapted themselves to new ways of doing things. Once the tide of war had turned at the Battle of Midway in 1942, there was scarcely any doubt as to the outcome of the conflict.