THE INVASION OF THE SOUTHERN MARIANAS in June and July of 1944 was part of a coordinated effort by U. S. forces to gain bases within striking distance by air of the Philippines and the Japanese home islands. The enemy position in the Pacific was weakening under strong Allied offensives, which moved along two lines converging on the Japanese inner zone. From Australia the Allied offensive had developed on an axis northwest along New Guinea and beyond the Bismarck Sea, and from Hawaii it had moved to the west through the Marshall Islands (Maps Nos. 1 and 2, pp. x and 2). The advance along both lines had depended upon the conquest of enemy islands selected to form a system of supporting garrisons from which air and sea power could neutralize the remaining enemy bases in the area.
By late spring Allied forces in the Southwest Pacific, pushing their advance along the northern coast of New Guinea, had reached Biak Island. Their network of forward bases in the Admiralty Islands and on New Guinea threatened Japanese holdings in the Netherlands Indies, the Caroline Islands, and even the Philippines. Eastward of Hollandia more than 100,000 enemy troops, cut from their sources of supply, were ineffective for future operations. To the north and east of the New Guinea thrust, Central Pacific forces had established a line of approach toward the Philippines, severing the enemy's communications east of Eniwetok atoll. The advance through the Central Pacific, begun a year later than that in the South and Southwest Pacific, protected the Allied positions in the Admiralties and on the New Guinea coast by weakening Truk, principal Japanese fleet base and aircraft staging center in the vicinity.
The next move, to the Marianas, was daring; it extended the Central Pacific spearhead more than a thousand miles to the west of the Marshalls, between the enemy-held Carolines on the south
MAP NO. 2 Central Pacific Islands
and Wake and Marcus on the north. The potential value of the southern Marianas was worth the risk. In addition to threatening the Philippines and the enemy supply line to the south, the conquest of these islands would furnish Central Pacific forces with their first bases for large-scale air attacks on Japan.
Offensive in the Central Pacific
Advance through the Central Pacific to the Marianas by U. S. forces meant penetrating deep into the Mandates, made up of the Marianas, Palau, Caroline, and Marshall Island groups, which the Japanese had controlled since World War I. Except for Guam, a possession of the United States since the Spanish-American War, these islands had been secretly fortified by the enemy prior to 7 December 1941. By overwhelming Guam four days after their attack on Pearl Harbor, and occupying the Gilbert Islands during September and October 1942, the Japanese controlled all the great island chains in the Central Pacific. For more than two years they had been
perfecting interdependent land, air, and sea bases on these chains to form a defensive system in depth, guarding their inner empire from attack on the east and south.
The offensive on the east, penetrating the chain barrier, had begun on 21 November 1943 under the command of Admiral Chester W. Nimitz, Commander-in-Chief, U. S. Pacific Fleet and Pacific Ocean Areas. The first blow struck by Admiral Nimitz involved the seizure of selected atolls in the Gilberts. His offensive required a powerful naval force, with carrier-based planes superior in fire power and maneuverability to the Japanese land-based aircraft, to make the initial attacks on the enemy defenses. Before the amphibious assault, carrier bombers, assisted by medium bombers flying from South Pacific fields, "softened" the enemy's position in the Gilberts. A naval convoy transported marine and army ground troops to the beaches, some 2,000 miles southwest of Pearl Harbor, and covered the invasion offshore. The Japanese garrisons fought tenaciously, but were destroyed in three days of fighting. Control of Makin, Tarawa, and Apamama neutralized or isolated all other atolls in the Gilbert group, making a systematic annihilation of each of the enemy's fortified bases unnecessary. On these three atolls engineers developed airfields for advancing the Central Pacific forces toward the Marshalls.
Continuing his tactics, Admiral Nimitz pushed the offensive ahead. Carrier groups ranged forward early in December to strike at enemy installations in the Marshall Islands. At the end of the month fighters and medium bombers, taking off from the new Gilbert strips, attacked Jaluit and Mili. A series of air raids reached all important Japanese bases, and some were made unserviceable. On 31 January marines and army troops invaded Kwajalein, an atoll in the center of the group. One of the largest fleet concentrations in naval history supported the landing. Again the Japanese fought hard, but by 5 February they had lost the atoll. The capture of Eniwetok, 350 miles to the northwest, a month later completed the bypassing of the remaining enemy bases in the Marshalls.
The two great Caroline and Marianas archipelagoes lay to the west, guarding the Philippines and the enemy supply lines from Japan to New Guinea and the Netherlands Indies. The Central Pacific forces immediately launched air and naval attacks on both groups. Large carrier-plane formations hit Truk in the Carolines late in February, sinking 19 ships and seriously damaging shore installations.
A strong task force, including hundreds of carrier-based aircraft, attacked Saipan and nearby Tinian on 23 February; a small raid by 12 fighters was made on Guam. These were the preliminary actions toward neutralizing the Carolines and preparing for an invasion of the Marianas.
During the following months air attacks against the Carolines and Marianas intensified. On 30 March a powerful task force of the Pacific Fleet hit bases in the western Carolines, destroying or damaging 46 Japanese ships and 216 planes, and inflicting heavy damage on shore installations. The naval unit in this attack, Fast Carrier Task Force (Task Force 58), under command of Vice Adm. Marc A. Mitscher, had been organized early in the year and was to play an important role in the growing offensive. On 11 June a task force struck at the southern Marianas. Carrier-based planes attacked Guam, Rota, Tinian, and Saipan. On the 13th the force, including battleships and cruisers, steamed in to shell Saipan and Tinian.
With this series of blows Admiral Nimitz's air and naval forces had paved the way for a full-scale invasion of the Marianas, despite indications of rapid enemy reinforcement of the islands. This advance into the heart of Japan's Pacific empire would represent a bound forward of 1,000 miles beyond our most recently conquered base at Eniwetok. Admiral Nimitz's forces would have to operate at distances from their main bases which once would have been considered prohibitive: 3,300 miles from Pearl Harbor and nearly twice that distance from California. His ability to undertake such an offensive reflected the great increase of American strength in the Pacific since 1942, an increase measured not only in the size of navy, marine, and army forces under his command, but in the potential of ships, weapons, and supplies furnished by war industries as far as 10,000 miles from the combat zone.
A month after the capture of Eniwetok, Admiral Nimitz decided that the southern Marianas were to be the next objectives in the Central Pacific. Strategically located 1,500 air miles from Manila and 1,600 air miles from Tokyo, the islands would provide his forces with bases almost equidistant from the Philippines and Japan, main Allied objectives. Admiral Nimitz's plan for the use of the southern
ORGANIZATION CHART Forces Engaged in the Invasion of the Marianas
MAP NO. 3 The Southern Marianas: Plan of Attack, III and V Amphibious Corps
Marianas was to "establish bases for operations against Japanese sea communications and for long-range air attacks against Japan," to "secure control of sea communications through the Central Pacific," and to "Initiate the isolation and neutralization of the central Carolines."
The principal force assigned to the mission by Admiral Nimitz was the Fifth Fleet, under command of Vice Adm. Raymond A. Spruance. Activities of all major commanders in the Pacific Ocean Areas and of General Douglas MacArthur, Commander of Southwest Pacific Area, were to be coordinated by the joint Chiefs of Staff in support of the Fifth Fleet. Timing for the invasion depended upon the completion of new Marshall Island bases and the assembly of sufficient troops and supplies.
All naval and ground forces designated for the Marianas operation were organized under joint Expeditionary Troops commanded by Vice Adm. Richmond K. Turner (Organization Chart, page 6). Admiral Turner's naval command was divided into two echelons, the Northern Attack Force under his immediate command and the Southern Attack Force under Rear Adm. Richard L. Conolly. Turner's ground units consisted of Expeditionary Troops under Lt. Gen. Holland M. Smith. The Expeditionary Troops were in turn divided into two echelons: one, the Northern Troops and Landing Force, composed of V Amphibious Corps, headed by General Smith himself; and the other, the Southern Troops and Landing Force, composed of III Amphibious Corps, under Maj. Gen. Roy S. Geiger. V Amphibious Corps consisted of the 2d Marine and 4th Marine Divisions, both reinforced, and garrison forces; III Amphibious Corps included the reinforced 3d Marine Division under Maj. Gen. Allen H. Turnage and the 1st Provisional Marine Brigade, also reinforced, under Brig. Gen. Lemuel C. Shepherd, Jr., and garrison forces. The army's 27th and 77th Divisions, commanded by Maj. Gen. Ralph C. Smith and Maj. Gen. Andrew D. Bruce, respectively, were both in expeditionary troops reserve.
While carrier-based planes and submarines made photographic studies of the enemy island defenses, the forces, comprising 500 vessels and 120,000 assault troops, were activated and assigned their individual missions. On D Day Northern Troops and Landing Force was to land on Saipan and then prepare to seize Tinian (Map No. 3, page 8). Capture of Saipan would help cut off the flow of enemy
reinforcements to Tinian, Rota, and Guam to the south. On W Day, Southern Troops and Landing Force was to invade Guam. The 27th Division was to be in floating reserve for any one or all three of these proposed operations. The 77th Division was to be held in strategic reserve in the Hawaiian Islands. D Day for Saipan was set for 15 June. W Day for Guam, designated tentatively as 18 June, depended upon the progress of land operations on Saipan and upon the movements of the enemy fleet.
Northern Troops and Landing Force proceeded to Saipan as planned. On
the beaches the marines suffered heavy losses from mortar and artillery
fire. The 27th Division was committed on D+1, and the Southern Attack Force
was brought in as floating reserve. After ten days of bitter fighting,
marine and army units occupied approximately one-half the small island.
during the last days of June was slow and costly, and not until 9 July was all organized enemy resistance declared at an end. The battle cost the 27th Division alone 4,038 casualties.
Enemy ground opposition on Saipan, combined with a powerful surface attack, slowed up the whole Marianas operation. Fifth Fleet's forces were engaged entirely in protecting joint Expeditionary Troops at Saipan. Even if the Southern Troops and Landing Force was considered strong enough without reserves for the Guam invasion, the fleet could not cover the landings as planned. On 16 June the battleships of the Southern Attack Force, initially scheduled to support the Guam invasion, maneuvered to the north of Saipan, while Admiral Mitscher's Fast Carrier Task Force moved westward into position in the Philippine Sea to protect the troops at Saipan from an impending enemy fleet attack. The next day cruisers and destroyers of the Southern Attack Force reinforced the Fast Carrier Task Force west of the Marianas. The enemy fleet attack materialized on 19 June when the Japanese Fleet Striking Force launched carrier planes against Admiral Mitscher's task force. The enemy planes made three heavy but uncoordinated assaults. Mitscher's fighters met each of the three enemy formations as they approached their targets on the 19th, and next day his whole air force delivered full-strength blows on the Japanese fleet. The enemy carriers had evidently planned to launch planes against the Fifth Fleet and then retire, leaving their fighters to escort the bombers to Guam airfields. From these strips torpedo bombers would then continue the attack. By the time the Japanese fleet retired to the west, it had lost nearly 400 aircraft and 14 ships.
The demands of the Saipan battle delayed the attack on Guam and Tinian, and W Day for Guam was indefinitely postponed. The transports carrying the Southern Landing Force, which were cruising in the area east of the Marianas, were ordered to sail to Eniwetok on 25 June to await further instructions. On 30 June Admiral Conolly and General Geiger flew from Guadalcanal to Saipan to confer with Admiral Turner and General Smith. They decided to set 21 July as W Day; to attach the 77th Division to the III Amphibious Corps; to make one RCT of the 77th available on W Day, and the remainder of the division not later than W Day+2. The change in W Day allowed time for transports to bring forward the 77th from Hawaii, reinforcing Southern Troops and Landing Force for the Guam attack.
MAP NO. 4 Guam (physiographic map)
The Island of Guam
Guam, Japanese-held since December 1941, is the southernmost of the Marianas. Its area of 228 square miles, the largest in the Central Pacific between the Hawaiian Islands and the Philippines, is approximately equal to the total area of the other 14 islands in the 600-mile-long Marianas chain (Maps Nos. 4 and 27, page 12 and inside back cover). The extreme length, north to south, is about 34 miles; the width, east to west, varies from 5 to 9 miles.
From a strategic standpoint Guam was important because it was large enough to become a principal forward staging area for further advance toward the Philippines and Japan. Apra Harbor, on the west coast north of the Orote Peninsula, provided safe anchorage deep enough to accommodate medium-sized vessels. The harbor also afforded landing and take-off lanes for seaplanes, which had been used by the Navy and Pan American Air Lines before December 1941. On land Guam had many sites for airfields suitable for the heaviest bombers. At least two fields built and used by the enemy were already in existence. One, a mile-long strip, was on Orote Peninsula; the other was east of Agana. In possession of United States forces, the island would be denied to the enemy as a refueling, supply, and -aircraft staging area.
Approaches to Guam present formidable obstacles to invading forces. Less than ten miles of the coast line are suitable for an amphibious assault, and these stretches only at higher stages of tide. Coral reefs, high cliffs, and heavy surf combine to deny most of the shore to landings in any force. The reef, continuous except for small breaks, fringes the entire island and fills many of the coastal bays. The greater portion of the reef ranges in width from 25 to 700 yards; to the southwest it extends toward Santa Rosa Reef for 2½ miles. The lowest reefs are covered by a few feet of water at mid or high tide, allowing only boats of two-foot draft to pass over them. Reinforcing the reef barrier along all the northern shore are high cliffs, rising sheer from the reef shelf or the narrow beach to heights of 600 feet. In the Apra Harbor area only small groups of men could attempt the cliffs extending around the western tip of Orote Peninsula, where an occasional ladder, concrete steps, or narrow trail through a notch lead from the shore to the mainland. The rough waters on the southeast side of the island also prohibit a landing
in force; there are a few openings in the reef, but the heavy surf restricts approach through these narrow breaks. At no point would the landings be easy. The least hazardous beaches are in Agat Bay from Facpi Point to Haputo Point, and to the northeast from Asan Point to Adelup, Point. Along both these stretches men could wade from the reef to the shore, if their landing craft could not pass the reef barrier. A further advantage was that neither stretch was blocked by a cliff. Their beaches are bordered by a coastal plain, a half mile to a mile in width, over which the men could push inland.
Overlooking these beaches the terrain rises from the coastal plain to a range of hills which dominates the western shore of the southern half of the island. Peaks in this range, the key hills for control of the entire island, reach heights of more than a thousand feet about two miles inland. Mt. Alifan (869 feet) and Mt. Tenjo (1,022 feet) command the southernmost of the two beaches; Mt. Chachao (1,046 feet) and Mt. Alutom (1,082 feet) command the northern. On the east side, the range gradually slopes down to foothills and a plateau stretching to the coast 100 to 300 feet above sea level.
Heights, primarily volcanic rock, are rugged and sparsely covered with tall, coarse, sharp-edged grass and scrub growth, except between Mt. Alifan and Mt. Lamlam (1,334 feet) where timber is found in large stands. Orote Peninsula and Cabras Island, on the west, and the coastal regions, on the east, are underlain by coral limestone. Here ravines and lower lands are heavily wooded and thick with tropical growth. Weeds, trailing vines, and tropical vegetation, consisting of strand trees intermingled with lianas, air plants, and underscrub, grow to six or eight feet, and at such rate as to make even roads impassable if they are not used constantly. Rice paddies and coconut groves are cultivated in the marshes and lowlands.
The topography of the northern half of the island differs markedly from that of the south. From Agana and Pago Bay a forested limestone plateau rises gradually to more than 600 feet at the northern end of the island. East of Agana, approach to the plateau is through an area of low hills, covered with palm trees. These hills merge into the plateau broken only by Mt. Barrigada (674 feet), Mt. Santa Rosa (870 feet), and Mt. Mataguac (600 feet). Four natural clearings exist in the forest, on Mt. Santa Rosa, Mt. Mataguac, at Finegayan, and near Pati Point; man-made clearings are restricted almost entirely to roads, limiting a military advance to the channels
of the existing road network. Because porous coral subsoil absorbs all rainfall, the section has no rivers. Pago River, northernmost of the island's five streams on the east coast, flows from the foothills of Mt. Chachao to Port Pago.
Tropical growth on the entire island thrives in the constant temperatures, with daily averages ranging throughout the year between 79° and 83° F. The rainfall is seasonal, with ranges from 15 inches a month upward. The summer monsoon period (July-October) is the wettest season, rainy days averaging 20 a month and the humidity staying near 90 percent or above.
About 100 miles of hard-surfaced, two-lane motor road existed on the island in 1940. This type of Class A road, built of a kind of soft coral rock, ran from Agat northward along the coast through Agana and beyond Mt. Machanao. A section of it extended inland and across the island to Barrigada, Finegayan, and beyond Yigo. Some stretches of this road were safe for speeds of more than 40 miles per hour, but for heavy traffic every mile of surface would require constant maintenance. A network of Class B roads, of single-lane width with no surfacing, supplemented the Class A two-lane highway through most of north Guam. Except during heavy rains, these secondary routes were good for light, rapid traffic moving in one direction.
From Agat to the south a Class B road joined a two-lane highway at Umatac, which skirted the island's shore to Pago Bay and crossed the waist of the island to Agana. Travel through the interior of southern Guam depended largely upon trails, some wide enough for bull carts. Military movement through south Guam would be limited almost entirely to the coastal two-lane highway.
The status of these roads in 1941 was the latest information the invasion forces had; it seemed unlikely that the Japanese had undertaken the difficult task of extending or improving them. However, engineers estimated that in northern Guam they could cut at the rate of a mile an hour a route wide enough for transporting artillery pieces, to relieve the existing roads of some traffic.
According to the 1940 census, there were about 22,290 permanent residents on Guam, more than half of whom lived in the main city of Agana. The remainder of the population lived in very small villages; only 8 towns, including Agana, had more than 500 inhabitants. Many of the natives, called Chamorros, are descendants of
the Spanish, Mexican, and Philippine soldiers who occupied the island after 1670, but others have American, British, Chinese, or Japanese forebears who came later and intermarried with the natives. Most of the Chamorros are Catholic, and almost all of them can speak some English. Although 80 percent engage in agriculture, their methods are so poor that the staples of their diet have to be imported. Evidence that the natives are loyal to the United States was their attempt to keep alive after December 1941 the six American survivors of the Japanese assault. The enemy discovered and killed all except George Ray Tweed, Radioman 1c, whom the natives guarded for more than two years as a symbol of continued American sovereignty over Guam. Generally friendly and docile, they had grown increasingly restive under the Japanese, but the extent of their opposition before American invasion was not known.
Japanese rule of Guam began after they overwhelmed the navy and marine
garrison of 555 men, who put up what resistance they could. At the time,
despite its importance to the United States, the island was not fortified.
Defending marines had only a few .30-caliber and .50-caliber machine guns
and no mobile artillery to use against an enemy task force estimated at
three cruisers, three destroyers, and a convoy of eight merchant ships.
The Japanese took over the naval
MAP NO. 5 Enemy Dispositions on Guam, July 1944
installations in Apra Harbor, the storehouse and repair shops at Piti, and cable facilities and marine barracks at Sumay. They recruited slave labor from the natives to assist in maintaining their base.
Enemy Forces on Guam
Once before in our history American assault units had appeared off Guam, but then it had been comic opera. On 20 June 1898., shortly after the beginning of the Spanish War, the Charleston fired a few shots from its secondary battery on Fort Santiago as a preliminary to occupation. The Spaniards did not know of the opening of hostilities far to the east; legend on Guam even has it that they interpreted the gunfire as a friendly salute. At any rate, their only defense was four small guns of obsolete design, formerly used for saluting but at that time condemned as unsafe, even for that purpose. The island was occupied without opposition by marines and by 2 companies of the 2d Oregon Infantry Regiment, taken to the shore by 25 rowers.
No one expected comic opera in 1944. The experiences of Tarawa, Makin, Kwajalein, and Eniwetok had shown the ferocious quality of Japanese resistance. The strategic importance of Guam indicated the probability that the enemy garrison would be strong, and the island's extensive land mass led the Central Pacific forces to expect a longer defense than that encountered in earlier operations. The fighting on Saipan did nothing to alter this estimate.
After the invasion of Kwajalein the III Amphibious Corps C-2 learned that the Japanese were transferring army troops from Manchukuo to Guam to reinforce the 54th Keibitai, nucleus of the naval units in complete charge of the island's defense (Map No. 5). The reinforcing army units from China, organized under the South Marianas Area Group, arrived on Guam in March. The group included the 29th Division (with the 18th and 38th Infantry Regiments) commanded by Lt. Gen. Takeshi Takashina, and the 6th Expeditionary Force. The force was composed of three infantry battalions, a field artillery battalion, and an engineer company of the 1st Division; and an infantry group headquarters, three infantry battalions, one mountain artillery battalion, and one engineer company of the 11th Division. In June the 6th Expeditionary Force was dissolved. The units of the 1st Division formed the 10th Independent Mixed Regiment
under Lt. Col. Ichiro Kataoka; those of the 11th Division became the 48th Independent Mixed Brigade under Maj. Gen. Kiyoshi Shigematsu. Before the invasion of Guam, III Amphibious Corps estimated that the total enemy strength on the island was about 18,500, of which 13,000 were army troops and 5,500 naval. On 14 July intelligence officers of the 77th Division were inclined to revise their estimates of the number of Japanese troops on Guam upward to more than 36,000. Division's higher figure, almost twice that of Corps', was based partly on units identified on the island, and partly on the potential capacity of the enemy to land additional troops on Guam until 15 June.
Known locations of Japanese army and navy troops in June placed the
2d Battalion, 18th Infantry in northern Guam, the 48th Independent
Mixed Brigade and part of the 29th Division in the Tumon Bay
area, the rest of the 29th Division in the waist of the island between
Agana and Pago Bay, the 54th Independent Guard Unit on the Orote
Peninsula, the 38th Infantry, except for the 5th Company
on Cabras Island, in the Agat sector, and the 10th Independent Mixed
Regiment to the southeast. Because the whole of the Agat sector was
relatively isolated by limited routes of communication from the more populated
areas to the north, the 38th Infantry, defending it, was more or
less independent of the rest of the island command. Although in June the
enemy had stationed his forces to cover the entire island, during July
he began to shift them to the areas most vulnerable to an attack from the
Captured documents indicated that the enemy considered these areas to be along the central portion of the west side of the island, where the coastal features presented the least formidable barrier to an invading force. According to the chart of installations compiled by the III Amphibious Corps, the enemy in the sector from Agana to Agat Bay had about twenty-five 75-mm mountain guns, ten 70-mm. to 90-mm howitzers, two 37-mm antitank guns, and more than thirty-five machine guns. These were supplemented by at least 25 naval coastal defense and dual-purpose guns. Rifle pits, trenches, and barbed wire added to the strength of the beach defenses, and mid-July studies indicated that the enemy was increasing their depth
MAP NO. 6 Preferred Plan of Attack on Guam, III Amphibious Corps
daily. The Japanese were also believed to have a large amount of mobile artillery and some tanks to lend support to their fixed positions along the shore.
Planning staffs of III Amphibious Corps knew that the enemy's defense of the island would be favored by the reef and the hills overlooking the most likely landing beaches, and that enemy defenses in those areas might indicate the intention of fighting hard at the shore. They later learned that the Japanese commanders were ordered: "While the enemy is advancing from the line of coral reefs to the shore, the combined infantry and artillery fire power will be developed. In particular when they reach the water obstacle, oblique and flanking fire will be employed to establish a dense fire net and thus annihilate them on the water."
Plan of Attack
The preferred plan for the assault phase of the operation on Guam, which the III Amphibious Corps had prepared in April and May, remained substantially unchanged after the capture of Saipan. The revisions, made possible by the postponement of W Day, increased the duration of the preparatory naval bombardment, strengthened Southern Troops and Landing Force, and provided for limited reconnaissance of the beaches prior to W Day.
Although the plan for the assault phase was simple it demanded close cooperation of all arms. The attack was to develop simultaneously on either flank of the military heart of the island, the Orote Peninsula, with its air strip, and Apra Harbor, with its installations (Map No. 6, page 22). Because high cliffs and a strong enemy coastal defense made a frontal assault on the peninsula and the harbor impossible, the plan involved landings north and south of Apra Harbor. From the north one force of the III Amphibious Corps was to drive toward the base of the peninsula and there meet the other force, which had meantime landed and approached from the south. The combined forces, having secured control of the hills commanding Orote, were to isolate and "pinch off" the peninsula from the rear.
Beaches chosen for the landings lay within the two stretches of shore most favorable for an amphibious assault. On the northern stretch, the landing beaches were designated at Asan between Adelup Point and the Tatgua River. On the southern stretch, they were
designated in Agat Bay between Agat village and Bangi Point. Although these beaches were the easiest portions of the island to assault from the sea, they afforded limited routes of approach to the interior, especially to the southern part of the island. Troops moving from the beaches could use the highway running along the coast in either direction, but the mountainous regions in the south were accessible only by trails and a few miles of surfaced and dirt road.
Using the limited routes from the beaches, the III Amphibious Corps was to secure a beachhead by seizing a final beachline on the ridge that commands both landing areas. The line was to extend from Adelup Point along Mt. Alutom, Mt. Tenjo, and Mt. Alifan
to Facpi Point. Once in control of a beachhead anchored on the final beachline, the corps would first attack Orote Peninsula from the east and then prepare to capture the rest of the island.
Corps assigned the northern and most heavily defended sector to the 3d Marine Division, which would land on the beaches between Adelup Point and the mouth of the Tatgua River, advance to the south, and occupy the area lying east of Apra Harbor. As the marine division moved to the south, it was to secure and defend the final beachline in its sector. The 1st Provisional Marine Brigade was to land on the beaches between Agat village and Bangi Point and then turn north in a wheeling movement into the base of the
Orote Peninsula. The 305th RCT of the 77th Division was chosen to support the brigade in this landing. The 2d Battalion with a platoon of the 706th Tank Battalion, boated in LCM's (Landing Craft, Mechanized), was to assemble between the launching area and the line of departure at H Hour+120 ready to land on brigade order. The 1st and 3d Battalions were to debark and land whenever the brigade called them. Once ashore, the combat team was then to occupy and defend the final beachline while the brigade attacked up the peninsula. The rest of the 77th initially was to be in corps reserve.
Two alternative plans were prepared by the corps, in case lastminute information disclosed that either of the beaches scheduled for landings under the preferred plan was too heavily defended or otherwise unsuitable. One of these provided for the entire invading force in echelon to go in over the beaches between Agat and Facpi Point, seizing Orote Peninsula and Apra Harbor, and overrunning the rest of the island from this beachhead. The other alternative plan was substantially the same as the preferred plan, except that the brigade would land between Bangi Point and Facpi Point instead of between Agat village and Bangi Point. However, the adoption of neither of these plans was necessary; the preferred plan was followed.
W Day had been set for 21 July; H Hour was to be 0830.
page created 28 June 2001
Return to Table of Contents
Return to CMH Online