Acting on reports from airmen that there were no signs of enemy activity and the islands might have been evacuated, General Douglas MacArthur accelerated his timetable for capturing the Admiralties and ordered an immediate reconnaissance in force.

[1] Los Negros curves horseshoe-like, forming a natural breakwater for Seeadler Harbour, the remainder of which is enclosed by Manus and a series of smaller islands.

In keeping with the overall Allied grand strategy of Europe first, the immediate aim of these operations was not the defeat of Japan but merely the reduction of the threat posed by Japanese aircraft and warships based at Rabaul to air and sea communications between the United States and Australia.

[5] At the Pacific Military Conference in March 1943, the Joint Chiefs of Staff approved the latest version of General MacArthur's Elkton plan for an advance on Rabaul.

[7] The Admiralty Islands, already a part of the Elkton plan, could serve this purpose, as they contained flat areas for airstrips, space for military installations, and Seeadler Harbour, which was large enough to accommodate a naval task force.

[2] On 6 August 1943, the Joint Chiefs of Staff adopted a plan that called for the neutralisation rather than the capture of Rabaul, and scheduled the invasion of the Admiralty Islands for 1 June 1944.

Under steady and relentless pressure, the Japanese air defence began to weaken, allowing a landing to be made on 15 February by New Zealand troops on the Green Islands, which lie little more than 100 miles (160 km) from Rabaul.

[10] Meanwhile, on 13 February General MacArthur, who received an intelligence windfall from the capture of Japanese Army code books by his Australian soldiers at Sio, had issued orders for the invasion of the Admiralty Islands, codenamed Operation Brewer, which was now scheduled for 1 April.

The remaining troops were carried on nine destroyers: USS Bush, Drayton, Flusser, Mahan, Reid, Smith, Stevenson, Stockton and Welles.

[17] It included the three rifle troops and the heavy weapons troop of the 2nd Squadron, 5th Cavalry; a platoon from Battery B, 99th Field Artillery Battalion with two 75 mm pack howitzers; the 673rd Anti-Aircraft Machine Gun Battery (Airborne);[18] and 29 Australians of the Australian New Guinea Administrative Unit (ANGAU), who were to assist in gathering intelligence and dealing with the native population, some 13,000 of whom lived in the islands.

[20] When an aide expressed concern over assigning such a hazardous mission to a unit without combat experience, General MacArthur recalled how the 5th Cavalry had fought alongside his father's troops in the campaign against Geronimo.

Krueger had a six-man party of Alamo Scouts inserted on the southern coast of Los Negros by PBY under cover of a bombing raid on 27 February.

In September 1943, as a result of the failure to stop Allied advances in New Guinea and the Solomons, the Imperial General Headquarters (IGHQ) had decided to constrict Japan's defensive perimeter in the south and central Pacific to a new line stretching from the Banda Sea to the Caroline Islands.

The IGHQ charged Imamura with holding his portion of the new line, which included the Admiralties, as long as possible to allow the Japanese navy and army time to prepare "decisive" counterattacks against Allied forces.

A subsequent proposal to transfer the 66th Regiment from the Palaus, where it was being rebuilt after suffering heavy losses, to the Admiralties was also unsuccessful as IGHQ believed that the Eighteenth Army had greater need for this unit.

The Imperial Japanese Navy (IJN) also rejected Imamura's suggestion that a special naval landing force unit be dispatched to the islands.

The 2nd Battalion, 1st Independent Mixed Regiment was led by reserve officers who had seen action in China, but most of its enlisted men were recalled reservists who had not previously been in battle.

[36] The first wave landed without casualties at 08:17, but once the bombardment lifted the Japanese emerged from their dugouts and machine guns and shore batteries began firing.

Fifteen dead officers and sergeants were counted, including Captain Baba, the commander of the Japanese battalion which made the attack the preceding night.

Two of the four B-25 squadrons dropped bombs in areas occupied by American troops, two of whom were killed and four wounded before the 12th US Air Liaison Party could correct the error.

Captain Emile Dechaineux, commanding the destroyers supporting the forces ashore, brought Ammen, Bush, Mullany and Warramunga around and bombarded the island.

Krueger realised that Hyane harbour was too small to support the entire division, but there were good beaches around Salami Plantation on the western shore of Los Negros.

[58] The main Japanese attack was delivered by 2nd Battalion, 1st Independent Mixed Regiment, from the direction of the native skidway, together with detachments from the Porlaka area, and fell on 2nd Squadron, 5th Cavalry.

Shortly after midnight, Japanese barges attempted to cross Hyane harbour but were engaged by anti-aircraft guns and did not reach the American positions.

[73] Joined by a third LVT which had eventually managed to make it to Salami, the LVTs made 16 trips across the harbour before nightfall curtailed operations, transporting part of the 2nd Squadron, 12th Cavalry, along with rations, water and ammunition, and evacuating the dead and wounded.

[84] The landing was covered by the destroyers Arunta, Bush, Stockton and Thorn;[86] a pair of rocket-firing LCVPs and the LCM (flak), which fired 168 4.5-inch (114 mm) rockets; the guns of the 61st Field Artillery Battalion on Los Negros;[80] and six Kittyhawks of No.

[83] The cavalrymen found well constructed and sited bunkers with interlocking fields of fire covering all approaches, and deadly accurate snipers.

Before dawn, two troops of the 8th Cavalry, six cargo carrying LVTs and the combat LVT were loaded on board an LST for the 18 kilometres (11 mi) trip across Seeadler Harbour from Salami.

[101]Discussions concerning the scope and nature of base development in the Admiralty Islands were held in early February between representatives of SWPA and Admiral William Halsey, Jr.'s neighbouring South Pacific Area (SOPAC).

[102] Admiral Nimitz recommended to the Joint Chiefs of Staff that development and control of the base facilities be placed under SOPAC by extending its border westward to include the Admiralties.