In May 1943, units from 17th Infantry of the U.S. 7th Infantry Division made amphibious landings on Attu to retake the island from Japanese Imperial Army forces led by Colonel Yasuyo Yamasaki…. Arctic weather conditions and exposure-related injuries also caused numerous casualties among U.S. forces. But after two weeks of relentless fighting, American units managed to push the Japanese defenders back to a pocket around Chichagof Harbor.
On 29 May, without hope of rescue, Yamasaki led his remaining troops in a banzai charge. The momentum of the surprise attack broke through the American front line positions. Shocked American rear-echelon troops were soon fighting hand-to-hand combat with Japanese soldiers. The battle continued until almost all of the Japanese were killed. The charge effectively ended the battle for the island, although U.S. Navy reports indicate that small groups of Japanese continued to fight until early July.
In 19 days of battle, 549 soldiers of the 7th Division were killed and more than 1,000 injured. The Japanese lost over 2,850 men; only 29 prisoners were taken alive.
Attu was to be the last action of the Aleutian campaign. The Japanese Northern Army secretly evacuated their remaining garrison from nearby Kiska, ending the Japanese occupation in the Aleutian Islands on 28 July 1943.