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Part Four: Guam

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Chapter 15: Plans and Preparations

The Island

To the invaders of Guam, southernmost of the Marianas chain, the physiography of the island presented essentially the same problems and challenges that had already been encountered at Saipan – those for Guam were just on a larger scale. Located a little more than a hundred miles south of Saipan, Guam is more than twice its size, measuring 228 square miles in area. From Ritidian Point in the north to the southern coast line, the distance is about thirty-four miles; the width of the island varies from five to nine miles.1 (Map V.)

Guam, like Saipan, is surrounded by coral reefs ranging in width from 25 to 700 yards. Even the lowest of these is covered at high tide by only about two feet of water – a condition that of course made the employment of amphibian tractors mandatory in the projected ship-to-shore movement. Around the entire northern half of the island from Fadian Point on the east coast to Tumon Bay on the west, sheer cliffs rising to 600 feet ruled that area out for landing. In the southern part of the island the shore line cliffs are somewhat less forbidding, but even so in many places, such as at the tip of Orote Peninsula on the west coast, they are still too precipitous to permit rapid movement inland by any large numbers of men approaching from the sea. The southern and southeast coasts, exposed as they are to the prevailing easterly winds, are pounded too heavily by surf to permit easy landing operations. This leaves about fifteen miles of coast line feasible for an amphibious assault, all on the west coast, north and south of Orote Peninsula. At various places in this region, the reef is low enough and the sandy beaches are both wide and deep enough to permit invading troops to get ashore and establish a foothold before assaulting the mountainous terrain inland.

Although nowhere does Guam’s mountain range reach the heights of Mount Tapotchau on Saipan, it still presents obstacles of no mean proportions. The northern part consists almost entirely of a coral limestone plateau broken by three elevations, Mount Barrigada (674 feet), Mount Santa Rosa (870 feet), and Mount Machanao (610 feet). The central part, the waist of the island between Agana Bay and Pago Bay, is mostly lowland draining into the Agana River through a wide swamp of the same name. Just south of the waist the land begins to rise again toward the mountain range that runs to the southern tip of the island. Dominating the northern part of this range are Mount Chachao, Mount Alutom,

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Cliff line at tip of Orote 
Peninsula

Cliff line at tip of Orote Peninsula

and Mount Tenjo, all inland from Apra Harbor and all attaining more than a thousand feet. East of Agat Bay below Orote Peninsula lies Mount Alifan (869 feet); south of it and inland from Facpi Point is Mount Lamlam, the highest point on the island (1,334 feet).2

Though Guam’s mountain mass is not so high as Saipan’s, its vegetation is lusher, heavier, and thicker. A degree and a half of latitude in this area of the world makes a difference, and Guam is considerably more tropical than the northern island. At the time of the invasion the northern section of Guam was heavily covered with tropical forests, weeds, trailing vines, lianas, air plants, and underbrush – all combining to make foot passage almost impossible except through man-made jungle trails. The mountain tops themselves were mostly barren volcanic rock covered only with sparse growths of sword grass and scrub. The southern plateau was covered mostly with sword, cogon, and bunch grass and scrub forest, except between Mount Alifan and Mount Lamlam, where timber grew in fairly large stands.

To facilitate passage over and through this rough and forbidding country there were, in the summer of 1944, about a hundred miles of hard-surface road, linked together by single-lane unsurfaced roads and a network of narrow jungle trails cut through the bush. The main road ran from the town of Agat along the west coast to Agana, then northeast to Finegayan, where it split into two parallel branches, each terminating near Mount Machanao near the northern tip of the island. Another branch of the same road ran northeast to the village of Yigo, where it dwindled into a narrow unsurfaced road that continued on almost to Pati Point, on the northeastern

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Orote Peninsula

Orote Peninsula

coast. Also from Agana to Pago Bay on the east coast stretched a main artery that continued south and west along the coast line to Umatac. Umatac and Agat on the west coast were connected only by a dirt road.

Except for the surfaced highways, the roads and trails were normally all but impassable during the rainy season, which lasted from July to November. During this summer monsoon period, 20 to 25 days out of each month were rainy. Mean temperature was about 87° Fahrenheit and average humidity about 90 percent – factors that would increase the discomfort of combat troops, whether American or Japanese.

Plans for the Invasion

Guam was initially included in the list of American targets for 1944 by the Joint Chiefs of Staff directive of 12 March 1944 that ordered Admiral Nimitz to prepare to seize and occupy the southern Marianas. Like the islands to the north, it offered sites for B-29 bases and, in addition, Apra Harbor was the best ship anchorage in the entire archipelago, having excellent possibilities for development into a small forward naval base. Then too, Guam, like the Philippines, had been an American possession; its native population was presumed loyal to the United States, and its liberation deemed a moral obligation.

Little more than a week had passed since the 12 March directive when Admiral Nimitz issued a preliminary order (dated 20 March) for the seizure of the southern Marianas, including Guam. Saipan and Tinian were assigned to the V Amphibious Corps. To the III Amphibious Corps, commanded by General Geiger, USMC, went the job of recapturing Guam.3

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Chart 2: Task organization 
for major commands for attack on Guam

Chart 2: Task organization for major commands for attack on Guam

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Maj

Maj. Gen. Roy S. Geiger

General Geiger was to have under his command the 3rd Marine Division; the 1st Provisional Marine Brigade, consisting of the 4th and 22nd Marine Regiments, reinforced; III Amphibious Corps Artillery; and the 9th and 14th Marine Defense Battalions. The 27th Infantry Division was constituted Expeditionary Troops Reserve for the entire force of the two corps. The 77th Infantry Division, commanded by Maj. Gen. Andrew D. Bruce – still in the United States but scheduled shortly to move to Hawaii – was designated Area Reserve. Twenty days after Saipan was assaulted, the 77th was alerted for movement into the Marianas.4

Command relationships between the top commanders for the Guam phase (Phase III) of the Marianas operation were to be in every way similar to those that were obtained for Saipan and Tinian. Under Admiral Nimitz, Admiral Spruance as Commander, Fifth Fleet, was in over-all command. Under him came Admiral Turner, Commander, Joint Expeditionary Force (Task Force 51), and General Holland Smith, Commander, Expeditionary Troops (Task Force 56), whose respective powers and responsibilities on this echelon of command have already been described.5 The Joint Expeditionary Force was in turn divided into two groups. The first, called Northern Attack Force (Task Force 52), also under Admiral Turner, was directed to land and support the assault troops on Saipan and Tinian. The second, designated Southern Attack Force, commanded by Admiral Conolly, USN, was given the same task for Guam. In like manner, General Holland Smith’s Expeditionary Troops was split into two parts: Northern Troops and Landing Force (Task Group 56.1) consisting mainly of the V Amphibious Corps plus the XXIV Corps Artillery and commanded also by General Smith was allocated to Saipan and Tinian; Southern Troops and Landing Force (Task Group 56.2), made up mostly of the III Amphibious Corps, commanded by General Geiger, was destined for Guam. The command relationships between General Geiger and Admiral Conolly were essentially the same as those that obtained between General Smith as Commander, Northern Troops and Landing Force, and Admiral Turner as Commander, Northern Attack Force.6 Thus, during the ship-to-shore movement,

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Conolly was to command the landing force through Geiger. Once Geiger determined that the status of the landing operation permitted, he was to assume command of the troops on shore and report that fact to the task force commander. (Chart 2.)

Planning for the invasion of Guam was somewhat complicated by the vast distances that lay between the headquarters of the various commanders concerned. General Geiger’s III Amphibious Corps headquarters was located at Guadalcanal; General Holland Smith’s Expeditionary Troops staff was at Pearl Harbor, as were Admirals Spruance, Turner, and Conolly and their staffs. The 77th Division was still in the United States during the period when the initial plans for the landing were being worked out.

On 29 March, General Geiger flew to Pearl Harbor, where for better than a week he conferred with General Smith and Admirals Turner and Conolly and their respective staffs. A week after Geiger’s departure from Pearl Harbor, Admiral Conolly flew to Guadalcanal, where the two commanders completed their planning and ironed out some of the many complicated problems involving naval-ground force coordination in the forthcoming landing.7

The upshot of these various conferences was the promulgation of one preferred and two alternate landing plans for Guam. The preferred plan called for simultaneous landings on the west coast by the 3rd Marine Division between Adelup Point and Tatgua River and by the 1st Provisional Marine Brigade between the town of Agat and Bangi Point. The landing day (designated W Day) was tentatively set as 18 June, three days after D Day for Saipan.8

To support the troops, Admiral Conolly split his Southern Attack Force into two groups, Northern and Southern Attack Groups. The former, commanded by Conolly himself, was, under the preferred landing plan, to support the 3rd Marine Division; the latter, to be commanded by Rear Adm. Lawrence F. Reifsnider, USN, would perform the same function for the 1st Provisional Brigade. The provisions for naval gunfire support during and after the landing closely paralleled those established for the Saipan operation. Before W Day, ships and aircraft of Admiral Conolly’s Task Force 53 were to coordinate their bombardments with scheduled strikes by aircraft from Admiral Mitscher’s Task Force 58. On W minus 2 and W minus 1, Task Force 53 was charged with responsibility for close-range support of underwater demolition teams and for destruction of coastal defense guns and antiaircraft and field artillery batteries on the landing beaches and of areas immediately inland. During the evenings ships of Task Force 53 were to provide harassing fires and some time during this period were to conduct a diversionary bombardment on the east coast of Guam.9

On W Day itself the first priority for the fire support ships would be counterbattery fire, beginning at dawn, on known and suspected enemy positions. Secondary attention would be paid to local defenses by close-range fire. Third priority would be given to interdiction fire against any roads

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leading to the landing beaches. Shortly before H Hour naval gunfire was to shift to close support fire on the flanks of the landing beaches. When the leading tractor waves were 1,200 yards from shore, cruisers were to lift their main batteries to the inland areas with an accelerated rate of fire to neutralize mobile batteries and mortars. Five-inch gunfire was to be maintained along the beaches while naval aircraft strafed and bombed the same area. When the leading assault wave of LVT(A)’s was 500 yards from shore, the 5-inch batteries were to shift fire to the near flanks of the beaches. One novel safety factor was introduced into the plans for Guam that had not been prescribed for the other landings in the Marianas. During the period when air and naval bombardment was to be conducted simultaneously, ships were ordered to restrict their fire to a maximum range of 8,000 yards, which meant in effect a maximum shell ordinate of about 1,200 feet. At the same time pilots were instructed to fly no lower than 1,500 feet.10

After H Hour, ships were to continue scheduled fires until ordered to stop. Call fires, it was planned, would be available as soon as communication with the shore fire control parties on the beaches was set up, and fire support ships were then to be prepared to deliver harassing fire, interdiction fire, star shell and searchlight illumination, and white phosphorus projectile fire on call.11

Admiral Conolly, as Commander, Northern Attack Group, was to control the naval fire in support of the 3rd Marine Division’s landing over the Asan beaches, while Admiral Reifsnider was to control bombardment of the brigade’s beaches in the Agat area. Control of aircraft over both sets of beaches was to be exercised by Admiral Conolly alone through his Commander, Support Aircraft, stationed aboard the task force flagship, the AGC Appalachian. This officer was assigned control of combat air patrols, antisubmarine patrols, close air support of troops, and a variety of special missions. He would control not only the planes flown from the carriers attached to Task Force 53 but also planes flown from the fast carriers of Task Force 58 from the time of their arrival over the combat area until their departure for recovery by their parent ships.12

Before the arrival of Appalachian in the Guam area, an Advance Commander, Support Aircraft, embarked on the cruiser Honolulu, would discharge these functions. A standby Commander, Support Aircraft, embarked in Admiral Reifsnider’s flagship George Clymer, was assigned the temporary additional duty of Commander, Landing Force Support Aircraft. He was to assume this role under the command of General Geiger after the latter had established his command post ashore. The plan provided that when the Landing Force Support Aircraft commander was ready to take control of aircraft (land-based and carrier-based) in direct support of the troops, he was to advise Admiral Conolly and thereafter, under Conolly, would assume control of all support aircraft over Guam. Requests for carrier-based and distant land-based aircraft were to be sent by the Commander, Landing Force Support Aircraft, to Admiral Conolly, who would effect the arrangements for getting the planes on station and notify the Commander, Landing

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Force Support Aircraft, of their estimated time of arrival at the rendezvous point.13 This procedure would automatically give the landing force commander (General Geiger), through his air representative, more direct control over the aircraft employed in the support of his troops than was the case at Saipan and Tinian. There the Commander, Attack Force Support Aircraft, afloat, had kept close rein on all troop support missions flown from carriers.

To avoid conflict between air support strikes and field artillery fire, Commander, Support Aircraft, or Commander, Landing Force Support Aircraft, was to request a cessation of fire from the commanding general of III Amphibious Corps Artillery for the duration of the air strike. Further coordination was to be secured through air observers, artillery spotters, and through the air coordinator. The function of the latter was to direct scheduled air strikes from the air and to report developments of the ground situation. Marine air observers were to keep General Geiger informed on the ground situation, while artillery spotters would direct Marine artillery fire.

Preliminary air strikes on Guam were to begin on D Day at Saipan and last until W Day minus 1 under direction of the Advance Commander, Support Aircraft. On W Day itself a major air strike was scheduled to last for half an hour, from H Hour minus 90 minutes to H Hour minus 60 minutes. During this period forty-six fighters and ninety-six dive bombers were to bomb and strafe gun positions and beach installations in the two landing areas and surrounding territory.14

Change of Plans

Following intensive amphibious training and rehearsals in the Guadalcanal area,15 the various Marine units of the III Amphibious Corps set sail aboard the transports and LSTs of Task Force 53 and arrived at the staging area at Kwajalein Atoll on 8 June. After a brief period allowed for fueling, watering, and provisioning, the convoy put to sea again and by 15 June had arrived at its designated assembly area over a hundred miles to the east of Saipan. There it waited for ten days, cruising idly through the open seas, while higher authorities debated the feasibility of an early landing on Guam.

Originally, W Day for the assault had been tentatively set as 18 June, but events on Saipan and in the adjacent waters made a postponement mandatory. As already indicated, the 27th Infantry Division, at first designated as reserve for the Saipan and Guam phases of the Marianas invasion, had to be committed in its entirety to Saipan. Furthermore, the Japanese Mobile Fleet had been sighted steaming toward the Marianas with the apparent intention of giving battle, and it was obvious folly to send the slow-moving troop transports and LSTs of Task Force 53 into the waters west of Guam. Hence, Admiral Spruance canceled W Day and ordered Conolly’s task force to remain out of danger well to the east of Saipan.

By 25 June the situation ashore on Saipan had improved sufficiently to warrant releasing the III Amphibious Corps from its duties as floating reserve for the V

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Corps. Accordingly, the ships carrying the 3rd Marine Division sailed back to Eniwetok where they were followed five days later by the rest of the vessels carrying the 1st Provisional Marine Brigade.16 By early July, with the Saipan battle over two weeks old, thought could at last be given to deciding on a firm date for the landing on Guam. As a result of conferences among Admirals Turner, Hill, and Conolly and Generals Holland Smith and Geiger, 25 July was recommended. These commanders deemed an earlier attack on Guam inadvisable because, as Admiral Spruance expressed it to Admiral Nimitz, “The character of enemy resistance being encountered in Saipan and the increase over the original estimates of enemy strength in Guam” made the presence of the entire 77th Infantry Division necessary.17

Admiral Nimitz was anxious to schedule the assault for 15 July, by which time it was presumed that at least one regimental combat team of the 77th Division could be dispatched to the scene of operations. Nevertheless, he deferred to the judgment of the officers present in the combat area and agreed to delay W Day until the whole of the Army division had arrived at Eniwetok. On 6 July Admiral Spruance was advised that the last two regimental combat teams of the 77th Division to leave Hawaii could reach Eniwetok by 18 July, four days earlier than expected. Consequently, W Day was advanced to 21 July. The 305th Infantry of the 77th Division was constituted reserve for the 1st Provisional Brigade and ordered to land on the Agat beaches sometime after the brigade had gone ashore. The rest of the division was designated corps reserve and was ordered to prepare to land “about William plus 2 Day on designated Beaches between Agat Village and Facpi Point” – also in the brigade zone.18

77th Infantry Division Training and Preparation

For the 77th Infantry Division, the invasion of Guam was to be the first chapter of a distinguished combat record in the Pacific war. Activated in March 1942, the unit spent its first two years in the United States undergoing training in basic infantry warfare and in various specialties such as desert warfare at Camp Hyder, Arizona, mountain warfare in West Virginia, and amphibious warfare in the Chesapeake Bay area. In May 1943 General Bruce assumed command of the division. A veteran of World War I, General Bruce was a graduate of the Infantry School, the Field Artillery School, the Command and General Staff School, the Army War College, and the Naval War College. Before he assumed command of the 77th Division he completed a tour of duty in the Operations and Training Division of the War Department General Staff and commanded the Tank Destroyer Center at Camp Hood.19

By March 1944 the division was located at Oahu, and for the next three months it was put through an intensive indoctrination in the techniques of warfare peculiar to the Pacific area under the direction of General Richardson’s United States Army

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Forces in the Central Pacific Area (USAFICPA). Infantrymen were trained as flame thrower and demolition men so as to avoid the necessity of relying exclusively on engineers to perform these functions in combat. Officers and noncommissioned officers took a forward-observers course to reduce dependence on artillery personnel. The 706th Tank Battalion trained with the infantry regiments in mutual close-in support, combined maneuver problems, and landing operations. The entire division spent six days at the Unit Jungle Training Center on Oahu. Amphibious training for the infantrymen consisted of net-climbing, embarkation, and debarkation from mock-up ships, transfer of personnel and equipment from LCVPs to LVTs at sea, and landing on beaches in wave formation. Artillery units conducted test landings from LSTs and practiced landing operations in DUKWs and LVTs with battalion landing teams. Experiments in loading and landing 155-mm. guns from LCMs, LSTs, and LCTs were made. The 77th Division Reconnaissance Troop held four days of practice with destroyer escorts, and part of the 292nd JASCO trained with Navy aircraft at Maui. The JASCO’s shore fire patrol party conducted destroyer firing exercises at the naval gunnery range on Kahoolawe Island. The only important feature missing from the program was the customary last-minute ship-to-shore rehearsal, which had to be foregone because of the lack of time. For most of the period the XXIV Corps, to which the division had initially been assigned, assisted in the training. Not until 22 June, almost on the eve of its departure from Oahu, was the division released to the V Amphibious Corps, the Marine Corps’ administrative and training command in the Hawaiian area.20

At the time the division set sail from Hawaii in the first week of July, it was still a matter of doubt as to how and where it would be employed on Guam. Not until the middle of the month when the troop transports had reached Eniwetok was General Bruce fully apprised of the intentions of his superiors in regard to his unit. This meant that there was very little time before the target date to complete plans and to disseminate them to subordinate units. An additional handicap was the fact that not until they arrived at Guam itself were the commanding general and his staff able to establish personal contact with higher, adjacent, and supporting units.21

Despite these difficulties, by 15 July General Bruce was able to promulgate three plans (one preferred and two alternates) for the division’s commitment. The plan already devised by III Amphibious Corps had contemplated the seizure of a Force Beachhead Line to extend from Adelup Point along the Mount Alutom–Mount Tenjo–Mount Alifan ridge line to Facpi Point. According to the corps’ preferred plan, the 3rd Marine Division would land between Adelup Point and the mouth of the Tatgua River and move south to the Apra Harbor area while the 1st Provisional Marine Brigade, with the 305th Regimental Combat Team of the 77th Division attached, would land between the town Agat and Bangi Point and then wheel north to the base of Orote Peninsula.

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Gearing his own plans to this schedule of operations, General Bruce directed the 2nd Battalion, 305th, with a platoon of the 706th Tank Battalion, to assemble at the line of departure two hours after H Hour and be ready to land on order of the 1st Provisional Marine Brigade. The other two battalions of the 305th were free of specific instructions except to be ready to debark and land, also on brigade order. As corps reserve, the 306th and 307th Regiments would land on corps order over the same beaches as the brigade, move to assembly areas, and be prepared to relieve the brigade of the duty of defending the final beachhead line.22

The two alternate plans prepared for the Army division’s commitment were both based on the assumption that the Marines’ preferred plan would be put in effect. One of these contemplated a landing by the 306th and 307th Infantry Regiments near Adelup Point, whence they would move southwest to assembly areas and be prepared to attack either south toward Mount Tenjo or southeast toward Pago Bay. The second called for landings by the same two regiments on the northwestern coast between Uruno and Ritidian Points, from which positions they would move southwest in order to secure from the rear a beachhead at Tumon Bay.23

This second plan was particularly dear to General Bruce’s heart.24 He wanted the two regiments of the 77th Division that were in corps reserve (the 306th and 307th) to land at dawn or just before dawn near the northwest tip of Guam about four days after the initial amphibious assault. They would then drive rapidly south and capture a beachhead at Tumon Bay from the rear. They would land without heavy equipment, but once the Tumon Bay beaches were secured necessary supplies and equipment and possibly other infantry elements could be landed there. The concept of the plan, as Bruce expressed it, was “for the 77th Division to become a hammer striking forwards and eventually on the anvil, i.e., the Force Beach Line. Should the enemy divert sufficient forces to halt this Division for any appreciable length of time it should be possible for the 77th Division to become the anvil and the forces occupying the FBL to become the hammer.”25

Immediately upon his arrival at Eniwetok on 11 July, General Bruce, with characteristic enthusiasm, pressed this scheme on the Marine commanders present. None of them warmed to the proposal, and Maj. Gen. Allen H. Turnage told him he had better drop the idea. The Marines were reluctant to divert the corps reserve to a secondary landing for fear it might be needed to support the assault troops at the main beachheads. Undaunted by this

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cold reception, Bruce sent a despatch outlining his plan to General Geiger, who had already sailed for the Marianas aboard Admiral Conolly’s flagship, Appalachian. The corps commander rejected the plan on the grounds that it was then too late to make any radical changes.26

Loading and Embarkation

77th Division

In the Hawaiian area where the 77th Division loaded and embarked for the Guam operation, its logistical needs were handled by the supply section of General Richardson’s headquarters and its subordinate agencies and by Commander, Service Force Pacific, a naval organization. Holland Smith’s staff determined the amounts of each class of supplies to be landed initially and supervised or at least checked the tentative loading plans. In the early phases of the logistical planning, it was not considered necessary to provide initial combat supplies to the division because the earlier operation plans did not call for its commitment within thirty-five days of the Marine assault landings.27 Once the division was designated area reserve and then, in mid-June, alerted for movement to the Marianas, supply activities were naturally accelerated.

General Bruce’s first supply order was issued on 24 June and specified the levels of initial supply for each class:

Class I

Rations

Type B 10 days
10-in-1 pack 10 days
Type C 7 days
Type K 3 days
Type D 2 days
Assault candy ration 2 per man
Rations accessory pack 20 days

Water

In 5-gallon containers and 55-gallon drums, 2 gallons per man per day for 5 days; 1 water point unit for each RCT; 2 water distillation units for each engineer combat battalion.

Class II

20 days maintenance of clothing, equipment, and general supplies, bulk clothing and individual equipment carried by RCTs to be equally distributed in all ships and landed early.

Class III

Fuels and lubricants 20 days

Class IV

Chemical Warfare 20 days
Engineer 20 days
Ordnance 20 days
Quartermaster 20 days
Medical 30 days
Signal 20 days

Class V

Antiaircraft weapons 10 CINCPOA U/F
All other weapons

7 CINCPOA U/F28

Like the 27th Division before it went to Saipan, and unlike any of the Marine divisions destined for the Marianas, the 77th complied enthusiastically with General Holland Smith’s directive that between 25 and 50 percent of all supplies be

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palletized.29 Altogether, the division built about five thousand pallets, but about a thousand of these were dismantled before being loaded aboard ship because they would not fit into available spaces in the holds or because they were too difficult to handle in holds where fingerlifts were not available.30 In contrast, the marines bound for Guam palletized none of their supplies, partly because they lacked the building materials and equipment to handle them and partly because they were still skeptical as to whether pallets could be satisfactorily hauled ashore over a coral reef.31

To lift the more than 18,000 troops and the 21,428 tons of supplies and equipment of the 77th Division from Hawaii to Eniwetok and then on to Guam, the Navy provided seven attack transports, four transports, three AKA’s, two AK’s, and three LSTs. The LSTs carried 612 troops and the 53 DUKWs allotted to the division. The DUKWs were the only amphibian vehicles allowed the 77th; no LVTs were taken along since the division was not scheduled to go into the beach in assault.32

Loading the vessels was complicated by the fact that the 77th Division had less than two weeks’ advance notice as to how many ships would be made available to it and what their characteristics would be. Loading plans therefore had to be sketchy and tentative, since they could not be made final until approved by the commanding officer of each ship. The vessels themselves did not arrive at Oahu until forty-eight hours before the date set to begin loading. To troops who were about to embark on their first amphibious operation, the delay of course was maddening. One battalion commander later recalled that his transport quartermaster, the troop officer in charge of loading, “worried for 5 straight days without sleep, as did most of his assistants.”33 The 305th Regimental Combat Team was the first of the regiments to be loaded, and it left Honolulu on 1 July. Embarkation was hasty, troops and cargo were loaded simultaneously, and much confusion resulted. The other two regiments had to await the return of transports that had been involved in the first phase of the Marianas operation at Saipan. They did not leave Hawaii until 8 July.34

The Marines

The Marine units embarking for the Guam operation had one distinct advantage over the 77th Division in that their assigned shipping was present in their mounting area, the Solomon Islands, well in advance of the embarkation date. Admiral Conolly and his staff arrived at Guadalcanal on 15 April for a stay of nearly a month of preliminary planning with the III Amphibious Corps. The naval forces assigned to Task Force 53 were largely from Admiral Halsey’s South Pacific Area and had engaged in the Hollandia operation before putting in to bases in the Solomons on 10 May. Before their return for attachment to Conolly’s task force, arrangements had been made to station

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them at Guadalcanal, Efate, Espiritu Santo, and Hathorn Sound so as to avoid overcrowding Guadalcanal and Tulagi.35

Because of the presence of the ships in the immediate area of the points of embarkation, there was ample time for the transport division commanders and ship captains to check thoroughly the loading plans of the various units. Such difficulty as was encountered centered primarily around the loading and embarkation of the 1st Provisional Marine Brigade, which had only recently been formed and had not had as much time to prepare detailed plans as had the 3rd Marine Division.36

More important was the fact that early in May the naval lift allotted to the assault units was unexpectedly ordered to carry more than five hundred troops of Maj. Gen. Henry L. Larsen’s Island Command Headquarters Group, which was destined for garrison duties on Guam after it was secured. This raised additional demands on the already limited shipping space, and the result was that the marines had to leave a good number of their organic vehicles behind when they sailed from the Solomons. Their supply of amphibian vehicles, however, was not curtailed. The 358 LVTs of the 3rd and 4th Amphibian Tractor Battalions were assigned respectively to the 3rd Marine Division and the 1st Provisional Marine Brigade. Their job, after delivering the assault troops ashore, was to transship cargo and personnel from landing craft over the reef and thence to shore. In addition to these vehicles, the marines were supplied with a hundred DUKWs.37

Preliminary Bombardment

Naval Gunfire

No matter what the immediate inconvenience to American forces caused by Admiral Spruance’s postponement of the scheduled landing day on Guam, the long-run consequences of that decision were fortunate. The postponement of W Day from 18 June to 21 July made possible a more prolonged preliminary air and sea bombardment against Guam than against any other island in the Pacific during the war. The marines of the III Amphibious Corps who had chafed and fretted at being confined to their ships in the sweltering lagoon of Eniwetok later had good reason to be thankful for their enforced inactivity.

The first American naval shells to hit Guam were fired from ships of a small task group from Task Force 53 on 16 June, the day after the landing on Saipan. For an hour and three quarters, the cruiser Honolulu, the battleships Pennsylvania and Idaho, and several destroyers, all supported by planes from accompanying aircraft carriers, bombarded the west coast of the island. The damage done appears to have been negligible, but the raid did alert the Japanese as to the probable American choice of landing beaches in the forthcoming invasion.38

The enemy ashore mistook the shelling for the usual last-minute preliminary to an assault landing, and one Army lieutenant wrote in his diary:–

For the first time I saw the enemy fleet and was under its gunfire. I regret very much that we are powerless to do anything but to look

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at the enemy which came in barely 10,000 meters away. They shelled us steadily for two hours. Our positions were hit fourteen times. Fortunately none was injured. ... We think that at last the enemy will land tonight, and so we will observe strict alert all night. We were issued hand grenades and are now waiting for the enemy to come.39

By next morning, of course, the American ships had disappeared over the horizon, much to the disappointment of the lieutenant, and probably of most of his comrades. Impatiently, he wrote, “If the enemy is coming, let him come. The spirit to fight to the death is high. We are anxiously waiting but nothing unusual has happened so far as dawn breaks.”40

The next surface ship strike against Guam occurred on 27 June when a small detachment of cruisers and destroyers (Task Unit 58.4.5) from Admiral Mitscher’s carrier fleet made a quick run into the waters off Guam and Rota, sank a small harbor tug and two barges in Apra Harbor, and set fire to some oil storage tanks ashore. Three days later Destroyer Division 46 shelled the airfields on Orote Peninsula.41

Then, on 8 July, began the greatest single naval bombardment program of the war – greatest at least in terms of time expended. For thirteen days the Japanese garrison on Guam was treated to the most spectacular display of shore bombardment that the U.S. Navy had yet produced. First to arrive were four heavy cruisers, twelve destroyers, and two escort carriers of Task Group 53.18 commanded by Rear Adm. C. Turner Joy. The group’s primary mission was to destroy coastal defense and heavy antiaircraft guns. Secondary targets were warehouses, command posts, communications facilities, and troop concentrations. Coordinating with the planes from two task groups of Task Force 58 that arrived in the area about the same time, the cruisers and destroyers were responsible for one half of the island while the planes bombarded the remainder. At noon each day the two exchanged areas of responsibility. Meanwhile, planes from the two escort carriers flew combat air and antisubmarine patrol. At night each warship delivered harassing fire against the island. On 12 July the battleships New Mexico, Idaho, and Pennsylvania arrived to add their bit to the fireworks. Two days later Admiral Conolly himself put in his appearance aboard the AGC Appalachian and thereafter personally took charge of coordinating all naval and air bombardment. The same day, the battleship Colorado joined the bombardment force, as did California and Tennessee on the 19th. By the time the marines arrived to invade the island, a total of six battleships and nine cruisers with their escorting destroyers were saturating Guam with naval shells of all varieties. For this period of thirteen days (exclusive of W Day itself) naval ammunition expenditures against shore targets totaled 836 rounds of 16-inch, 5,422 of 14-inch, 3,862 of 8-inch, 2,430 of 6-inch, and 16,214 of 5-inch shells.42

At the invasion of Roi-Namur Admiral Conolly had earned the sobriquet “Close-in Conolly” for his insistence that warships

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cruise close to shore when firing at land targets.43 At Guam, he reaffirmed his right to the title, but more important was the systematic procedure he introduced for coordinating naval gunfire and aerial bombardment and checking the results of each. A target board of six officers, representing the air, gunnery, and intelligence sections of the staff, was set up to assign primary missions for air strikes and naval gunfire and assess the damages daily before designating the next day’s targets. Aerial photographs were taken each morning and on the basis of these damage was assessed and new targets were assigned. In these operations, the admiral’s staff was aided by the presence aboard Appalachian of General Geiger who, as commanding general of the landing force, naturally had the greatest personal concern about the accuracy both of the bombardment and of the damage reports submitted afterward.44

During the later stages of the preliminary bombardment, one additional duty was imposed on the ships present – that of supporting naval underwater demolition teams. Altogether, three teams were made available for the Guam landings. The procedure was one that had by now become standardized in the Pacific. Swimmers disembarked from their mother APD into LCPRs that took them close to the reef before putting them in the water to swim in the rest of the way to inspect the reef itself. In the meantime, four LCI gunboats lay to just off the reef and fired their 40-mm. and 20-mm. guns over the heads of the swimmers. On each flank of the LCI(G)s was a destroyer firing five-inch shells farther inland, while the APD followed astern of the line of gunboats, also firing. After the small boats had picked up their swimmers, the covering ships continued their fire on the beaches in an effort to interdict the area where the enemy was attempting to make repairs.

On 14 July Underwater Demolition Team 3, aboard the APD Dickerson, arrived in the area and for three days conducted reconnaissance of the chosen landing beaches and other segments of the western coast line. On 17 July Underwater Demolition Teams 4 and 6 put in their appearance. Actual demolition work began that evening. The obstacles discovered on the Agat beaches were chiefly palm log cribs filled with coral and connected by wire cable. On the Asan beaches wire cages filled with cemented coral were spaced about every five feet. Only occasional strips of barbed wire were found, and no underwater mines. Altogether, 640 obstacles were blown-up off Asan and about 300 off Agat by hand-placed demolitions.45 Some of these, at least, had been constructed as recently as 3 July, by which time the Japanese had been tipped off as to the probable landing beaches to be used by the invaders.46

Aerial Bombardment

In preparing the way for the amphibious assault on Guam, four main duties fell to the air arms of the Army and Navy. They were to neutralize Truk and the other islands in the Caroline group from which the Japanese might be expected to send

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their own aerial strength into the southern Marianas, prevent intervention by Japanese carrier-borne planes, photograph the island, and soften the target itself with an accelerated program of aerial bombing and strafing.

Starting in mid-March and continuing even after Guam had been secured, Army Air Forces bombers of the Seventh, Thirteenth, and, later, Fifth Air Forces conducted a series of devastating raids against the Carolines, chiefly Truk and Woleai. On one occasion, during the last two days of April, they were joined by Admiral Mitscher’s Task Force 58, which dropped 748 tons of bombs on Truk while retiring from the Hollandia invasion. The major credit for keeping the Carolines neutralized, however, fell to the Army Air Forces. By the time of the invasion of the southern Marianas, the island of Truk, once the leading Japanese bastion in the Central Pacific, had been rendered virtually useless.47 A like fate had befallen the great Japanese Mobile Fleet at the hands of Task Force 58 during the Battle of the Philippine Sea. By 20 June it was clear that the invaders of Guam need have no fear of serious Japanese threats from the air.

To Task Force 59, commanded by Maj. Gen. Willis H. Hale, AUS, fell the chief responsibility for aerial photographic reconnaissance of the Marianas. Seventh Air Force and shore-based Navy bombers, both under General Hale’s command, maintained armed reconnaissance over all the southern Marianas for more than two months before the first landings on Saipan. The first mission over Guam was carried out on 6 May by ten Army B-24’s escorting six Navy PB4Y’s. Five of the planes were shot down over the target by enemy fighters; six others were damaged. Again on 24 May, 29 May, and 6 June flights of B-24’s and PB4Y’s made the trip over Guam, taking photographs and dropping token loads of bombs on targets of opportunity.48 Of the 6 June raid, a Lieutenant Imanishi wrote despairingly, “There were 9 B-24’s,49 but not one of our planes went up to meet them. We felt disheartened. Just how desirous our air force is of fighting is open to doubt.”50

Desirous of fighting or not, the Japanese pilots stationed on Guam were soon to lose the means of doing so. Shortly after the photographic flight on 6 June, Admiral Mitscher’s fleet showed up to begin its methodical destruction of enemy aircraft and air facilities. In the belief that the island would be invaded on 18 June, Commander, Task Force 58, first unleashed his mighty armada of fighters and bombers against Guam and nearby Rota on 11-12 June. In the ensuing air battle, a total of 150 Japanese planes was reported destroyed in the air or on the ground. For the next four days, one or more of Mitscher’s task groups carried out strikes against aircraft facilities, runways, coastal guns, and antiaircraft positions on Guam and Rota.51

Against this overwhelming naval airpower, the Japanese were almost helpless. Wrote Lieutenant Imanishi, “It is especially pitiful that we cannot control the air. We can only clench our fists with anger and

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watch.”52 At the same time, a Japanese private noted that he and his companions were unable to leave their shelters and help repair the damage because of the bombings.53 Another enlisted man complained, “The number of enemy planes was said to be more than 500 today, while not one of our planes took to the air. I felt a bitter resentment at the manner in which the enemy stressed his air power.”54

Yet there was still some fight left in the Japanese air contingent on Guam, for on the evening of 15 June a few planes took off from Orote field to launch a low-level torpedo attack against the American carriers offshore. As a result, two of Mitscher’s task groups next day concentrated heavily on Guam to prevent a repetition of the previous evening’s attacks.55 During the two-day Battle of the Philippine Sea, the fields of Guam again received the attention of Mitscher’s fliers. Japanese land-based planes still undamaged by previous raids, as well as carrier planes that had flown in from Ozawa’s fleet, constituted a threat on Mitscher’s flank and rear that could not be overlooked. On the morning of 19 June, before the Great Marianas Turkey Shoot had even gotten well under way, two separate air battles were fought over Guam, both ending in victory for the Americans. Even during the course of the main battle itself, which was fought well out to sea, Mitscher kept one contingent of fighters and bombers over Guam to interdict the airfields and prevent any remaining planes from taking off to join Ozawa’s carrier planes. Altogether, about fifty Guam-based planes were destroyed on the 19th alone, and the fields themselves were at least temporarily put out of business.56 That night, when about fifteen Japanese carrier bombers attempted to make emergency landings there, they found the fields too torn up to do so and, being out of fuel, had to crash.57

The raids of 19 June all but delivered the coup de grâce to Japanese airpower on Guam. Occasionally, in the weeks that followed, a few Japanese planes flew into Orote from Yap and other islands in the Carolines, but they posed no real threat. On 4 July one of Mitscher’s task groups (Task Group 58.3) returned to conduct a daylight raid over the island, and from 6 through 17 July two other carrier groups (Task Groups 58.1 and 58.2) alternated daily in strikes over Guam and Rota. Primary targets were coastal and antiaircraft guns, supply dumps, airfield installations, and the towns of Asan, Piti, and Agat. These strikes were coordinated with those of the escort carrier planes and the naval bombardment ships of Admiral Conolly’s Task Force 53.58 On the last three days before the landing, the Japanese on Guam witnessed the full weight of American naval airpower in a mounting crescendo of aerial fury. On 18 July planes from the two task forces flew 662 bombing sorties and 311 strafing attacks, on the 19th the number increased to 874 and 392, and on the day before the landings to 1,430 and 614. The total tonnage of bombs,

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depth charges, and rockets dropped and launched during these three days came to 1,131.59

Assessment of Damage

As night closed in on 20 July, it seemed impossible to those aboard the flagship Appalachian that the Japanese on Guam could put up anything but token resistance to the troops that would go in the next day in amphibious assault. Maj. William M. Gilliam, USMC, who was Geiger’s naval gunfire officer, reported, “When the morning of the landing arrived, it was known that the assault troops would meet little resistance.”60 Admiral Conolly’s staff believed, “Not one fixed gun was left in commission on the west coast that was of greater size than a machine gun.”61

These conclusions were to prove somewhat extravagant, as the marines next day discovered to their sorrow. Testimony given after the war by Lt. Col. Hideyuki Takeda, IJA, who was a staff member of the 29th Division, provides a corrective to the American reports on which these optimistic conclusions were based.

Conventional construction, Takeda reported, consisting of buildings reinforced on an emergency basis, was completely destroyed when it received direct hits. Field positions that were hit by shells were completely destroyed, and of those on or near the landing beaches, over 50 percent were demolished. Half-permanent positions in which the hard agent cascajo (a type of coral) was used and that were reinforced with concrete about 50-cm. thick remained in good condition except in cases of direct hits. Those that were hit by shells were more than 50 percent destroyed. Permanent positions with concrete over one meter thick remained in perfect condition even after receiving direct hits. All open naval gun emplacements were completely destroyed before the landings. Of those naval guns emplaced in caves, about half remained operational at the time of the landings, but they were soon put out of commission by counterbattery fire that closed up the cave mouths where they were located. Antiaircraft artillery on the island sustained damage from naval gunfire only once, and so long as Japanese antiaircraft ammunition lasted the Japanese were reasonably safe from American planes. Harbor installations received almost no damage, water pipes received only one direct hit, and power installations were all located in caves and so escaped damage. Most military boats were sunk. Naval gunfire had no effect against construction in the valleys or in the jungle and had very little effect against the interior parts of the island over two and a half miles from the shore line.

American airpower, reported Colonel Takeda, succeeded in knocking out the airfields on Guam but posed little threat to defense positions because there was little bombing of Japanese gun emplacements from the air. By far the most important effect of aerial bombing and strafing was the extreme limitation it placed on Japanese ground movement during daylight hours. However, neither naval guns nor aircraft succeeded in causing any serious interruption in communications on Guam. Takeda could not remember a single case where telephone lines were cut because of naval gunfire. As of 21 July, Headquarters,

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29th Division, in command of the defense of Guam, possessed perfect wire and wireless communications with the 18th Infantry Regiment, the 38th Infantry Regiment, the force on Orote Peninsula, forces south of Pago on the east coast, and forces at Tarague on the north tip of the island. Perfect field telephone communication with the 48th Independent Mixed Brigade was maintained. Headquarters also had uninterrupted wireless communication with Rota, as well as with Imperial General Headquarters in Tokyo.62

In spite of the limited effectiveness of American preliminary bombardment, Takeda’s testimony does indicate that it produced certain substantial results. Many of the buildings that were destroyed by direct hits, such as hospitals, warehouses, and office buildings in the towns of Piti, Agana, and Agat, housed military personnel and equipment. Takeda’s own appreciation of the important role played by American air and sea power in reducing the defenses of Guam emerges through the crude but clear translation of the closing words of his postbattle report:

Among the battle colored by the holy blood of the dead I can find out the only lesson: The powerful air and sea powers make ground forces to defend island unnecessary. That is, the defence of island depending merely upon the isolated and helpless ground forces cannot be existed in the world. If the defence depending only upon the ground forces succeeded it would only be due to the fact that the island was neutralized, troops on it would hardly exist and they could perform their duty to defend the island because the enemy did not land on it.63

Intelligence of the Enemy

Considering the fact that Guam had been a U.S. possession for more than forty years, American intelligence of the island’s road system and terrain was remarkably incomplete. The War Department in June 1943 had prepared and published a general survey of the island, and in February 1944 the Office of Naval Intelligence circulated a voluminous bulletin containing all kinds of information about hydrographic conditions, ground contours, road systems, weather, and the native population.64 Neither of these studies was any further up to date than 10 December 1941, the date of the Japanese occupation, nor could the information supplied by American servicemen and native Guamanians who had lived on the island before the occupation give the planners any idea of Japanese defense installations or dispositions. General Geiger asked permission to send in small patrols by submarine to contact natives and “see behind the curtain,” but the request was turned down. Hence, for up-to-date data on the activities and progress of the Japanese garrison, reliance had to be placed entirely upon photographic reconnaissance, chiefly aerial.65

Not until 25 April, after Conolly’s staff had arrived on Guadalcanal, were photographs received, and the first ones were badly obscured by cloud cover. Later, aerial photographs were only fair, but were supplemented by excellent obliques of the coast line taken by the submarine USS

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Greenling. Maps of the interior, prepared from prewar sources and revised on the basis of these aerial photographs, were fairly good as to scale and azimuth, but only occasionally did they portray ground contours accurately. Changes made by the Japanese in the road system were not indicated on the maps provided the troops; in fact, in the north of the island map locations of the roads were as much as 1,500 yards off from their true positions. Trails were not shown at all.66

With the capture of Saipan, a good number of Japanese documents were made available to the planners for Guam and afforded them for the first time some idea of the enemy situation. On the basis of these documents and of interrogations of prisoners of war, the intelligence section of III Amphibious Corps estimated that Guam was garrisoned by a total of 17,673 Army troops and 9,945 to 10,945 Navy, Air, and construction personnel. Although these figures proved to be considerably in excess of actual enemy strength, Geiger’s staff correctly predicted that the bulk of the Army troops on the island was composed of the 29th Division under Lt. Gen. Takeshi Takashima and the 11th Infantry Regiment under Maj. Gen. Kiyoshi Shigematsu.67 The principal naval unit on the island was thought to be the 54th Naval Guard Force, and it was believed that about 2,185 naval air personnel were stationed there as well.68

It was assumed, on the basis of these documents and interrogations, that the Japanese would concentrate their defenses around Tumon Bay, Agana, and Agat, all on the west coast. Only two battalions were thought to be garrisoned on the south and southeast coasts. American troops about to invade Guam were warned to expect a large amount of mobile artillery and a determination on the part of the Japanese to exploit the mountainous terrain, which provided excellent observation. The enemy was thought to be holding back (from the beach defense) a mobile reserve of at least one battalion plus supporting weapons in the Agana area. A smaller reserve of about reinforced company strength was believed to be located somewhere inland of Agat.

“It seems evident,” concluded Geiger’s intelligence section, “that both we and the Japanese have been thinking along the same lines, that is, the beaches we find best for landings are those the Japs find most dangerous to them and have fortified the most.”69 The conclusion was fully warranted.

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