The major naval base construction started with the Los Negros landings on February 28, 1944.

United States Navy Seabee built or repaired the facilities on the islands.

The large Manus Naval Base, also called the Admiralty Island base, supported United States Seventh Fleet, Southwest Pacific command, and part of the Pacific Fleet.

The other reason was Manus Island's Seeadler Harbor, which offered the largest and most protected Southwest Pacific fleet anchorage.

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.

To support the activity at Hyane Harbor a small-boat repair depot and camp was built.

For ship repair, different sized Auxiliary floating drydocks were towed to the base.

At the captured coastal Lorengau Airfield a large supply depot was built.

Some bases were turned over to the Royal Australian Navy and later to the Papua New Guinea Defence Force.