Admiralty Islands

The Admiralty Island chain consists of about 20 volcanic islands, with a total land area of about 800 square miles (2020 km²), located just north of the eastern end of New Guinea, very near the Equator. They are rugged and covered with jungle. Most of the coasts are fringed with coral reefs, leaving only a few small beaches suitable for landing operations. The largest island, Manus, is 49 miles long and 16 miles wide (89 km by 26 km) and its central mountains reach to 2355' (718 meters). Northeast of Manus is found a superb anchorage, Seeadler Harbor, which is 15 miles long by 4 miles wide (24 km by 6km) and was of considerable strategic value in the South Pacific campaign. The main settlement is at Lorengau, on the south of Seeadler Harbor.

The group was discovered by the Dutch in 1616 and given its Western name by Captain Philip Carteret of the Royal Navy in 1767. Controlled by Germany prior to the First World War, the islands were mandated to Australia in 1920. In 1939 there were only 44 Westerners, mostly plantation managers, living in the island group. The indigenous population numbered about 13,000 Melanesians who were favorite subjects for study by prewar anthropologists. The islands produced small quantities of copra, turtle shells, and pearls, the latter heavily exploited before the war by Japanese divers from the Caroline Islands to the north.

The islands were also completely undeveloped, with no roads outside the immediate vicinity of Lorengau. A native trail ran along the north coast of Manus, and three trails crossed the interior mountains to the south coast. The Japanese bombed Lorengau on 21 January 1942, occupied Manus on 8 April 1942 with 51 Transport Regiment from 51 Division, and completed a 4000' (1220 meter) airstrip at Momote on the island of Los Negros, east of Seeadler Harbor. In 1943 they completed a 3300' (1005 meter) airstrip at Lorengau. At the same time the garrison was reinforced with elements of 14 Base Force and a battalion each from 1 Independent Mixed Regiment and 229 Regiment. The garrison remained relatively small, numbering about 4600 troops.

Operation BREWER: The Admiralties Campaign

In July 1943, following his decision not to attempt to take Rabaul, MacArthur was encouraged by the Joint Chiefs of Staff to take the Admiralty Islands instead. The group was strategically located, had a superb protected anchorage at Seeadler Harbor, and had ample flat ground for airfields on Los Negros, east of the harbor. Furthermore, by seizing the Admiralties, MacArthur would bypass the large Japanese force at Hansa Bay on the north New Guinea coast. A target date of 1 January 1944 was set, but this was pushed back to 1 March due to the Cape Gloucester landings and a dispute over the appropriate command arrangements: Halsey controlled the Seabee units needed to build up the naval base. The decision to make Halsey responsible for developing the base was not made until 28 February 1944.

On 22 February 1944, a flight of B-25s found no evidence of Japanese forces at Los Negros and Lorengau. The air strip was overgrown and no troops or vehicles were visible. MacArthur chose to disregard radio intelligence indicating a garrison of four to five thousand troops, and authorized a reconnaissance in force with the intention of converting this into a full-scale assault if resistance proved light. The order went out on 1500 on 25 February 1944 with the target date was set at 29 February. Kinkaid had to order the shore patrol to quickly round up the crew of light cruiser Phoenix so that she could sail in time to support the landings.

On 27 February 1944 a reconnaissance by six men from 158 Regiment was brought in by Catalina and went ashore by rubber raft. At 0645 the lieutenant in charge radioed that he "Could not get to river. Lousy with Japs." He and his men were extracted the next day. However, MacArthur felt it was too late to cancel the operation.

Two days later, elements of 5 Cavalry Regiment were landed on Los Negros. The landing beach selected was at Hyane Harbor. It was very narrow and most of the shore was mangrove swamp, but there was a landing leading directly to Momote Airfield. Colonel Ezaki Yoshio was expecting landings due to interception of U.S. submarine signals, but he expected the landings to be at Seeadler or southeast Los Negros and his troops were poorly deployed to meet the landings. Air support and naval gunnery in support of the landings were effective and Momote Airfield was seized by 0950. That night, Chase wisely abandoned the southern half the airstrip to tighten his perimeter.

On 2 March the second echelon arrived to find the beachhead under heavy fire. The LSTs unloaded as their gunners opened fire with 3" guns and 0.50 machine guns and B-25s and P-40s from 5 Air Force strafed Japanese positions. Seven hours later the ships were unloaded and pulled out. The Seabees went immediately to work clearing the taxiway between the beach and the runway and the runway itself. Debris scraped from the runway provided convenient cover for the troopers digging in on the west edge of the runway. "One 53-year-old operator drove his grader the full length of the strip three or four times, drawing sniper fire from the coconut grove. When he came in he said, 'I'm sure glad Mother let me come this time; you know, she wouldn't let me go to the other war!'" (Morison 1950)

On 3 March the Americans went over to the offensive, seizing the revetments west of the airfield. The Japanese counterattacked at 1900, one column moving over a causeway passing from the Momote area to the northern part of Los Negros. Heavy gunfire support from offshore destroyers and minesweepers broke up the this column, and the other two Japanese columns were poorly coordinated and were broken up by rifle and machine gun fire as they tried to make their way through mines and trip wires.

On 4 March the beachhead was reinforced by 7 Cavalry Regiment. The Cavalry continued to expand their perimeter and easily beat off a counterattack that night. By 9 March the Allies controlled about half of Los Negros, and had suffered 116 dead and 434 wounded while killing 1288 Japanese. A group of 68 Sikhs from the Indian Army who had surrendered at Singapore and been impressed as labor troops were taken prisoner.

Reconnaissance elements landed on Manus on the 11th and found the island strongly defended. Hauwei island was likewise probed and found to be heavily defended the next day. However, Hawei was overrun on the 13th and artillery emplaced to support the attack on Manus on the 15th. Lorengau airfield was captured on the 17th, and organized resistance on Manus ended on the 25th. It took until 23 March to reduce the last pocket of Japanese resistance on western Los Negros. The final Japanese strongpoint, on Pityilu Island, was heavily bombarded by destroyers and assaulted on 30 March. Although a few hundred Japanese escaped into the interior of Manus, the campaign was effectively over by 3 April 1944.

Total Allied casualties were 330 killed or missing and 2200 wounded, included 10 Seabees killed and 59 wounded. Japanese casualties were 4380 killed and 75 taken prisoner. The wild interior of Manus became known as "the Reservation" since green infantrymen were sent there to hunt Japanese survivors in order to give them some combat experience before deploying further forward.

The Admiralties campaign was a remarkable gamble, with a 1-to-4 ratio of attackers to defenders in its early stages. It succeeded only because of massive Allied air and sea superiority, which prevented the Japanese from shifting troops by barge and made them vulnerable to defeat in detail.

American order of battle

Japanese order of battle

Following the Allied victory, Momote airstrip was extended to 7800' (2380 meters) by mid-May 1944. Lorengau was abandoned but a new 8000' (2440 meter) airstrip was built at Mokerang on the northwest end of Los Negros in April. A second runway was later added at Mokerang and the Navy built a 5000' (1520 meter) runway on Ponam Island, off the north coast of Manus well to the west of Seeadler, and a 4500' (1370 meter) runway on Pityilu.

References

Dunnigan and Nofi (1998)

Miller (1959)

Morison (1950)

Rottman (2002)

Spector (1985)

The Pacific War Online Encyclopedia © 2007-2008, 2010 by Kent G. Budge. Index

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