Japanese called Los Negros Island the Hyane Island and had built some facilities on the two islands. Manus Island was picked for a major air and sea base as it was near
Empire of Japan strong points: 387 miles to
Rabaul, 694 miles to
Truk, 273 miles
Kavieng and 244 miles to
Wewak. The other reason was Manus Island's
Seeadler Harbor, which offered the largest and most protected Southwest Pacific fleet anchorage. By March 1944 the beaches were secured enough that the Seabees started construction. The first airfield captured was Hyane Airfield which was renamed
Momote Airfield. While the airfield was captured the outlining area still had fighting and the airfield was attacked two times while under construction. Hyane Airfield has one 4,000-foot runway in poor condition. On March 10,
fighter planes began using the Momote Airfield. Seabees completed all Momote Airfield construction and improvements on June 1, 1944 and turned the 7,800-feet runway Momote Airfield over to the
United States Army Air Forces. The newly built air base had a camp, 90 fighters and 80
bombers, a tank farm with 17,000-barrel
aviation gasoline that was filled from a small
T1 tanker harbor and an
ammunition depot. On April 1, 1944 Seabees started construction at
Mokerang Airfield on Los Negros Island with the US Army engineers. The existing runway was improved to 8,000 feet and a new second 8,000 feet runway was built. Built at Mokerang Airfield were: a base camp, supply depot, repair depot, and a 30,000-barrel tank farm. At Hyane Harbor Seabees constructed a 500-bed evacuation
hospital for the US Army. For the US Navy, at Hyane Harbor Seabees built a waterfront complex: two
cargo ship wharves, a repair pier, 800-foot ship refueling pier, and a ship unloading and repair crane. Also starting on June 19, 1944, at Hyane Harbor was a
pontoon assembly depot, as it was found that shipping pontoon flat, unassembled took a lot less space in ships. The pontoon depot had a personnel camp and warehouses. For the US Army and Navy a large aviation supply depot was built. For the Navy a 5,000 runway was built and a 7,000-barrel aviation-gasoline tank farm. To support the activity at Hyane Harbor a small-boat repair depot and camp was built. As the built up in the Pacific continued in April 1944, two new camp constructions were started on Los Negros Island: Papitalai Point and one at Lombrum Point. At Papitalai Point Seabee 58th Battalion built a base camp, depot, a
PT boat overhaul base,
fuel oil and
diesel tank farm. Seabee started work at Lombrum Point on April 17, 1944, which become
Lombrum Naval Base. At Lombrum Point Seabee built
seaplane repair base, a
ship repair base, and a
Landing craft repair base. Each base required the building of camps, depots, piers and shops. Landing craft base supported
LCT,
LSM, and a host of smaller landing craft. For ship repair, different sized
Auxiliary floating drydocks were towed to the base. The largest
USS AFDB-2 and
USS ABSD-4 were able to
drydock battleships. Also at Lombrum Point Seabee built a seaplane base with a concrete seaplane ramp and 8,000-barrel tank farm. At the captured coastal
Lorengau Airfield a large supply depot was built. Lorengau Airfield was a 3,500-foot grass runway and due to lack of space, it was not improved, but a support camp and depot was built at the Lorengau Airfield. Navy Base headquarters was built at Lorengau, near the mouth of Lorengau River. At the Lorengau Navy Base Seabee built a 1,000-bed Navy Hospital 15. The headquarters also had a camp for 5,000 men incoming Troops. Pityilu Airfield, on
Pityilu Island was built to support aircraft carriers, with a training center and storage of 350 spare fighter planes for later aircraft carrier use. Ponam Airfield on
Ponam Island was also built to support aircraft carrier fighter planes. After the war, most bases were abandoned in 1946 and 1947. Momote Airfield became
Momote Airport. Some bases were turned over to the
Royal Australian Navy and later to the
Papua New Guinea Defence Force. ==Bases and facilities==