The 'Battle of Attu' was the ground fight of the 'Landcrab' amphibious operation, and was fought between US and Canadian forces on the one hand and Japanese forces on the other for the island of Attu in the Aleutian islands group off the western coast of Alaska (11/29 May 1943).

The 'Battle of Attu' was the only land battle in which Japanese and Allied forces fought in sub-arctic conditions and, lasting more than two weeks, ended only after most of the Japanese defenders had been killed in hand-to-hand combat after a final banzai charge had broken through the US lines.

The strategic position of the islands of Attu and Kiska off Alaska’s coast meant their location could control the sea lanes across the northern tracts of the Pacific Ocean. Japanese planners believed control of the Aleutian islands group would therefore prevent any possible US attacks from Alaska on the Japanese home islands. This assessment had already been intimated by a US pioneer of strategic bombing theory, Brigadier General W. L. Mitchell, who had told the US Congress in 1935 that 'I believe that in the future, whoever holds Alaska will hold the world. I think it is the most important strategic place in the world..

On 7 June 1942, six months after the USA had entered World War II, the 301^st Independent Battalion of Lieutenant General Kisaburo Hamamoto’s Japanese Northern Army had landed unopposed on Attu island in 'Aq', one day after the 'Aob' landing on nearby Kiska island. The US military now feared that both of these islands could be turned into Japanese strategic air bases from which attacks could be launched against mainland Alaska and the rest of the US west coast.

On 11 May 1943, units of the 17^th Infantry of Major General Albert E. Brown’s (from 28 May Brigadier General Eugene M. Landrum’s) 7^th Division made amphibious landings on Attu to retake the island from the Imperial Japanese army forces, more specifically the 2^nd District, North Seas Garrison led by Colonel Yasuyo Yamasaki. These forces comprised the 83^rd Independent Infantry Battalion, the 303^rd Independent Infantry Battalion, the Aoto Provisional Anti-Aircraft Battalion, the Northern Kurile Fortress Infantry Battalion and mountain artillery and engineer elements. Despite heavy naval bombardments of Japanese positions, the US troops of the Northern Force (1/17^th Battalion Combat Team) and the Southern Force (2/17^th, 3/17^th and 2/32^nd Battalion Combat Teams) encountered strong entrenched defences that made combat conditions extremely difficult. Arctic weather and exposure-related injuries also caused numerous casualties among the US forces. After two weeks of relentless fighting, however, US units managed to push the Japanese defenders back to a pocket around Chichagof Harbor.

On 21/22 May, a powerful Japanese naval force was assembled in Tokyo Bay in preparation for a sortie to repel the US attempt to recapture Attu. The force included the aircraft carriers Zuikaku, Shokaku, Junyo and Hiyo, the battleships Musashi, Kongo and Haruna, the cruisers Mogami, Kumano, Suzuya, Tone, Chikuma, Agano and Oyodo, and 11 destroyers. The Americans, however, completed their recaptured of Attu island before this naval force could depart.

On 29 May, and now without any hope of rescue, Yamasaki led his remaining troops in a banzai charge. The surprise attack broke through the US front-line positions, and deeply shocked US rear-echelon troops were soon fighting in hand-to-hand combat with Japanese soldiers. The battle continued until almost all of the Japanese had been killed. The failure of this charge effectively ended the battle for the island, although US Navy reports indicate that small groups of Japanese continued to fight until a time early in July 1943 and isolated Japanese survivors held out until as late as 8 September. In 19 days of combat, 549 men of the 7^th Division, which had been reinforced by three more battalion combat teams, one engineer battalion and one anti-aircraft regiment, had been killed and more than 1,200 injured. The Japanese had lost more than 2,351 men, including Yamasaki, and only 28 men survived to be taken prisoner.

The 'Battle of Attu' was the last action of the Aleutian islands campaign. The Northern Army secretly evacuated its last remaining garrison, on the nearby island of Kiska, ending the Japanese occupation in the Aleutian islands group, on 28 July.

The loss of Attu and the evacuation of Kiska came shortly after the death of Admiral Isoroku Yamamoto, commander-in-chief of the Combined Fleet, who was killed by US aircraft in 'Vengeance'. These defeats compounded the demoralising effect of Yamamoto’s loss on the Japanese high command, yet despite the losses, Japanese propaganda attempted to present the Aleutian islands campaign as an inspirational epic.