Battle of Biak The Battle of Biak was part of the New Guinea campaign of World War II , fought between the United States Army and the Japanese Army from 27 May to 17 August 1944 . It was part of General Douglas MacArthur ' s Southwest Pacific command ' s offensive drive to clear New Guinea in preparation for an invasion of the Philippines . It was the first major effort by the Japanese to allow uncontested landings for the purpose of creating a kill zone inland . Background . The island of Biak dominates the entrance to Geelvink Bay , near the western end of New Guinea . The island was held by 11 , 000 Japanese troops under the command of Colonel Kuzume Naoyuki . Disdainful of the doctrine of destruction at the water ' s edge , he decided instead to allow the Americans to come ashore unopposed so that they would stroll unwarily into the trap he had prepared for them . This would turn the area around the vital airfield there into a martial honeycomb of caves and pillboxes filled with riflemen , automatic weapons , artillery , batteries of mortar s , and Type 95 Ha - Go light tanks . Kuzume also stockpiled these positions with enough ammunition , food and water to sustain his defense for months . Water was less than abundant on Biak , where heat and humidity would take a toll equal to enemy gunfire . It was known from an intercepted message dated 5 May 1944 that the IJA 2nd Area intelligence thought that next allied landing would probably be on Biak , and a preliminary landing was made on 17 May at Wakde on the way to Biak . There a smaller airfield was available , which could be used as an advanced base until the Biak strips were ready . While initial G2 estimates of enemy troops was approximately 5000 , an intercepted message at the end of April gave the ration strength as 10 , 800 , though it was thought this was a figure based upon projected , rather than , current strength . Battle . The 41st Division of the United States Army landed on Biak on 27 May 1944 , initially with the 162nd Infantry Regiment , and soon followed by the remainder of the division . By 5 : 15 in the afternoon 12 , 000 troops had landed , with 12 Sherman tank s , 29 field gun s , 500 vehicles and 2400 tons of supplies . It was to be their bloodiest fight . After a brief attack on the beachhead by a group of Japanese light tanks , defeated by a group of M4 Shermans , the regiment moved inland quietly confident and expecting little opposition . This perception all changed when they reached the airfield , where from out of low - lying terrain and the ridges above came a terrible storm of shot and shell that pinned them to the ground . It was not until dark that amphibious tractors could be brought up to extricate them from the trap . The next day they reached the end of Mokmer airstrip . Sorido airstrip was the objective . The Japanese held firm , delaying the capture of Mokmer airstrip . With the slow progress the US command pulled their forces back , relieved General Fuller of command of the 41st Division and reinforced the division with the 34th RCT of the 24th Infantry division . The 34th RCT made the assault on the airfields taking Mokmer 2 days later . The US forces had been delayed 10 days . With the delay , the 5th Air Force Command looked for alternative sites from which they could operate . They arranged the capture of the nearby island of Owi on 2 June and built two 7 , 000 ft airstrips there . An advanced echelon was stationed there composed of a bombardment group , two fighter groups , a P - 61 Black Widow night fighter group , and a garrison of 15 , 000 troops . Control of Biak nearly became a critical turning point battle in the campaign for the Pacific . The Japanese had been seeking to engage the Americans in a decisive battle , the Kantai Kessen , that would enable them to win the war . Biak was not far from major Japanese fleet units and there were a number of land airfields near by that could support the land based aircraft the Japanese were hoping to concentrate to defeat the US fleet . The Imperial Navy ' s Chief of Staff , Admiral Ryunosake Kusaka , believed Biak represented the allies ' main effort , and a counterattack at Biak could provoke the US Navy into engaging in a major action . Admiral Toyoda , commander of the Japanese Mobile Fleet , initially attempted to reinforce Biak to hold the airstrips , but his first reinforcement sent 1 June was turned back when a Japanese scout plane mistakenly reported a US aircraft carrier in the vicinity . A second relief effort on 8 June was intercepted and driven off by American and Australian naval forces . A third attempt , with the support of the super - battleships Yamato and Musashi was scheduled for 13 June , but the American invasion of the Marianas forced the Imperial Navy to redirect their forces to the Marianas for a major confrontation in the Philippine Sea . No . 1 Wireless Unit RAAF , an radio transmission intercept and monitoring unit , learned that at the time of the invasion Lieutenant General Takuzo Numata , the Chief of Staff of the 2nd Area Army , was on the island for an inspection tour . He sent messages to command requesting to be evacuated . A float plane was sent in from Korin Bay on the night of 20 June to bring him off . After two more days of intense fighting , Colonel Kuzume burned the regimental colours , indicating to his men that the regiment would make the defense of Biak their final battle . He then committed hara kiri , showing his men he did not fear death . The Americans broke through the Japaneses defences on 22 June , with a coastal strip from Bosnek to Sorido captured , including the three airfields at Sorido ( 4500 ft ) , Borokoe ( 4500 ft ) and Mokmer ( 8 , 000 ft ) . There were about 3 , 000 Japanese remnants trying to organize a final counterattack up to 17 August . One oddity Bleakley recalls is of a bamboo shack of Japanese recreational equipment in a sort of PX containing " dozens of pairs of ice skates " – " on a Godforsaken island on the equator ! " . He kept a pair as a souvenir for a while , and says the Japanese troops were told they were on an island off San Francisco and were soon to invade America . He was with No . 1 Wireless Unit RAAF , the only Australian forces on the island . Aftermath . The capture of Biak Island cost the Americans nearly 3 , 000 casualties , with 474 killed and 2 , 428 wounded . The Japanese fought to annihilation , with 6 , 100 killed and 450 submitting to being captured . In addition , some 4 , 000 Japanese were unaccounted for , missing in action and presumed dead . Biak was a grinding , shot - for - shot battle . The Japanese tactics of allowing the landing and delaying their firing until there were a great many targets were repeated at the Battle of Peleliu , the Battle of Iwo Jima , and the Battle of Okinawa . The losses suffered in these battles convinced the United States Marine Corps and the United States Army that ultimate victory would be costly , not only in time and equipment , but in the far more valuable lives of their servicemen .