Guam

U.S. Army

Guam is the largest of the Mariana Islands with a length of 32 miles (51 km) and an area of 225 square miles (583 km²), more than the rest of the Marianas combined.  The island has a damp climate, with daily rains during the wet season (July to December.) Temperatures are between 69-91F (21-33C). The southern half of the island is mountainous with a maximum elevation of 1334' (407 meters) at Mount Lamlam. The northern portion of the island is a relatively flat plateau (400' to 500' or 120 to 150 meters in elevation) ending in high cliffs close to the shoreline. The island is more heavily vegetated than the other Marianas, with the higher peaks heavily forested and the remainder covered with scrub and grassland. There are numerous streams draining into the southeast coast, and some of the low ground in the southern half of the island is swamp. The northern plateau is so heavily vegetated that it was actually less developed than the rugged southern half, where most of the cultivated land was found. The only portion of the coast suitable for amphibious landings was the southwest coast, where the offshore reef was less formidable and there were no high cliffs immediately behind the beaches.

Unlike the other Marianas, which belonged to Japan, Guam was a U.S. territory in 1941, having been purchased from Spain as part of the settlement of the Spanish-American War in 1898.  The other Marianas were sold to Germany by the Spanish, and seized by Japan early in the First World War.

The United States did little to develop Guam as a military base.  It was strategically located in the western Pacific, but its port at Apra (144.67E 13.43N) was cramped and shallow, and the island was in a very exposed position.  Furthermore, the Washington Treaty prohibited any American fortification of Guam. However, the Americans did construct Piti Naval Yard on the west end of the harbor and build a causeway to Cabras Island, which lies north of the harbor. Facilities included a 800-yard (730-meter) pier at the southwest end of Cabras Island, a breakwater, and numerous jetties and fueling docks.

Fortification was considered after the lapse of the treaties, but the island was so exposed that it was essentially written off by military planners. The American population remained small, consisting mostly of Navy administrators and their families, and there was little economic development apart from the fueling station. Efforts were made to improve health care and education for the native Chamorros, but they were otherwise left largely undisturbed, a policy sometimes described as "salutary neglect" (Morison 1953). The population in 1941 was 23,400, of whom 12,550 lived in the island capital of Agana.

On 8 December 1941, the garrison consisted of 156 Marines, 271 sailors, and 246 native soldiers of the Guam Insular Guards. Ships in the harbor included AM Penguin and AG Robert L. Barnes, a fuel storage ship.

Guam was subjected to air raids shortly after the attack on Pearl Harbor, and fell just three days later to a company of 2 Maizuru SNLF (370  men) and South Seas Detachment (Horii; 4886 men) after token resistance by the tiny Marine garrison.  The Japanese Navy renamed the island Omiya Jima, "Great Shrine Island", made Japanese the language of instruction in the local schools, and put most of the adult male population to work constructing airfields. There was one on the Orote Peninsula, which forms the south shore of Apra Harbor; a second northeast of Agana; and a third still further northeast that was never completed. The treatment of the Chamorros deteriorated further after the Japanese Army garrisoned the island in 1944, when all schools and churches were closed and the food supply confiscated. Hundreds died in concentration camps and a number of Chamorros were executed for sympathizing with the Americans.

An important collaborator on Guam was Samuel T. Shinohara, who was born in Japan, drifted into the Japanese Mandates, and eventually settled on Guam. During the Japanese occupation, Shinohara declared his allegiance to the occupying authorities, assisting in confiscation of Guamanian goods, abusing internees, and committing two rapes. He also organized a Dai Nisei organization to promote cooperation with the occupiers. Tried by the U.S. Navy after the war, Shinohara was spared the hangman's noose for treason when his defense lawyers pointed out that he was not a U.S. citizen, and instead he received a sentence of eight years' imprisonment at Sugamo Prison in Tokyo.

The island was recaptured from the Japanese in 1944 after a bloody campaign in which Saipan and Tinian were also taken.  Thereafter it became an important forward base and headquarters for the Pacific Fleet.

The Battle of Guam

Guam was originally scheduled for invasion on 18 June 1944. However, the invasion was postponed due to the Battle of the Philippine Sea and because the difficulty encountered in conquering Saipan convinced the American leadership that three divisions would be needed to conquer Guam. The third division would be 77 Division from Oahu, the Pacific Ocean Areas general reserve. The delay allowed the Japanese to construct elaborate beach defenses, but it also allowed the Americans to conduct a thorough and systematic reconnaissance and bombardment.

The latter began on 8 July and was commanded by the able Rear Admiral Richard Conolly, who also commanded the invasion fleet. Photoreconnaissance was conducted each morning to allow a combined team of six Navy and Marine officers to evaluate the results of the previous day's bombardment. Ammunition expenditure was 6258 16" (406mm) and 14" (356mm) rounds, 3862 8" (203mm) rounds, 2430 6" (152mm) rounds, and 16,214 5" (127mm) rounds. It was the most prolonged and systematic bombardment of the war. A Japanese officer who escaped into the bush and turned himself in after the Japanese surrender told American interrogators that the bombardment destroyed all coastal defenses in the open and about half of all emplacements that were under cover, as well as proving a severe test of Japanese morale.

Beach reconnaissance was carried out by Underwater Demolition Team 3 on 14 and 15 July 1944, which discovered how extensive the beach defenses were. These consisted primarily of coral and concrete landing craft obstacles, sometimes connected by steel cables. The frogmen began demolition of obstacles on 17 July and had destroyed 300 coral cribs and 640 wire and coral cubes by the time of the landings.

Landings began on Guam on 21 July 1944, preceded by a final massive bombardment by ships and aircraft. Some 55,000 troops of the III Amphibious Corps (Geiger) came ashore against a garrison of 19,000 troops built around 29 Division (Takashina) and 48 Independent Mixed Brigade (Shigematsu). The commander of 31 Army, Obata, was also caught on Guam by the Saipan landings, but initially left Takashina in command of the defenses. Landing beaches were selected north and south of Apra, the chief prize, with 3 Marine Division (Turnage) landing on the north and 1 Provisional Marine Brigade (Shepherd) landing to the south. After establishing themselves ashore, the two Marine forces were to execute a pincers movement against Apra, then clear the remainder of the island.

The landings to the north used LVTs to bring infantry across the reef, while LCMs disgorged tanks at the reef rim at positions previously marked by frogmen. Resistance was only moderate and almost the entire division was ashore by the end of the day. The beach was surrounded by high ground that favored the Japanese defenders, but American fire superiority was so great that the Japanese were mostly pinned down during the day. A counterattack at dawn on 22 July was repulsed, and 21 Marine Regiment had seized most of the crest by 24 July. Meanwhile 9 Marine Regiment conducted a shore-to-shore landing on 22 July that seized Cabras Island, which forms the north shore of Apra Harbor.

The Japanese staged their largest counterattack on 25 July. The counterattack was well planned and was carried out skillfully. In one place the Japanese penetrated as far as an American field hospital, where the corpsmen and even some of the more lightly wounded patients took up rifles to repel the assault. However, attempts by the Japanese to reinforce their initial penetrations failed when naval gunfire broke up troop concentrations, and by noon on 26 July the counterattack had been repelled. At least 3500 Japanese were killed.

Thereafter 3 Marine Division moved quickly to secure the plateau behind the northern landing beaches. Takashina was killed on 28 July and Shigematsu had been killed earlier, leaving the Japanese bereft of experienced combat leadership. The elderly Obata was forced to take personal command of the defense. That same day, 3 Marine Division made contact with 77 Division, closing the pincers on Apra Harbor.

The landings to the south were carried out by two regiments of 1 Provisional Marine Brigade. Battleship Pennsylvania moved very close to shore to neutralize flanking fire from the Orote Peninsula, but could not prevent the Marines from taking serious casualties coming ashore. Heavy fire came from a concrete blockhouse at Gaan Point that had been missed by reconnaissance and was in position to enfilade the beach. However, the Marines secured their first objectives before noon, and a tank attack destroyed the Gaan strong point later in the afternoon. The first elements of the reserve 77 Division began coming ashore late in the afternoon against much reduced Japanese fire. A Japanese counterattack that night was broken up when its supporting tanks were destroyed by Marine bazooka teams backed by a platoon of Sherman tanks. A second counterattack at daybreak on 23 July was broken up by cruiser fire.

With most of 77 Division ashore by 26 July, 1 Provisional Marine Brigade turned its attention to the Orote Peninsula. Here the Marines met with savage resistance. On 27 July a ferocious bombardment by warships and aircraft was so shattering to the Japanese defending the ridge overlooking the airstrip that they broke and ran, an almost unheard-of occurrence. The peninsula finally fell on 28 July, and that afternoon the top American commanders assembled with a color guard to raise the American flag over the Orote Peninsula for the first time since 1941. Engineers began repairing the airfield (which was ready for aircraft by 30 July) and yard craft began improving the harbor.

The Americans learned from the Chamorros and their own patrols that the Japanese had retreated into the wild northern half of the island, leaving a rearguard northeast of Agana. The Americans resumed pressing forward on 31 July, with 3 Marine Division on the left, 77 Division on the right, and 1 Marine Provisional Brigade in reserve.  Agana was occupied by noon. The Americans had the Japanese bottled into a small pocket in the north by 8 July, and the island was declared secure two days later. However, General Obata's command post was not actually overrun until 12 August, and as many as 9000 Japanese took to the jungle for the remainder of the war.

American casualties were 1435 dead or missing and 5648 wounded. The Americans had buried 10,693 Japanese bodies by 1 September 1944 and had taken 98 prisoners of war. The Japanese beheaded some 30 natives during the battle, whose bodies were discovered by a patrol from 21 Marine Regiment on 7 August 1944. By the time of the surrender, 19,000 Japanese had been accounted for, including 1250 prisoners.

A small number of Japanese soldiers remained hidden in the jungle following the general surrender of August 1945. The officers among the stragglers fell to fighting among themselves and the survivors became highly secretive. The last of these, Sergeant Yokoi Shoichi, did not give up until January 1972.

Allied order of battle, Guam invasion

Japanese order of battle, Guam invasion

Following its capture by the Americans, Guam was rapidly developed into a permanent base, with an oil tank farm having a capacity of 430,000 barrels. Apra Harbor was redredged and the breakwater and other facilities expanded. The runway at Orote Airfield was extended to 5000' (1520 meters) and the two runways north of Agana were extended to to 7000' (2130 meters). A third runway of 6000' (1830 meters) was completed north of Agana and two 8500' (2600 meter) runways were completed in the northern part of the island.

The island also became an important staging area for supplies. For example, refrigerated provisions ships broughtin full cargoes of fresh meat from Australia and New Zealand (reverse Lend-Lease) which were stored in refrigerated warehouses until they could be included in the balanced cargoes of ships headed to the combat zone.

References

Maga (2001)

Miller (1991)
Morison (1953)

O'Brien (1994; accessed 2011-5-28)

The Pacific War Online Encyclopedia © 2007, 2009, 2011-2012 by Kent G. Budge.  Index

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