The Battle of the Aleutians (3 June 1942 – 15 August 1943) was a campaign of the Pacific theater of World War II that occurred when the Japanese launched a diversionary assault on the Aleutian Islands, located off the coast of the US territory of Alaska in the northern Pacific. The Japanese believed that controlling the Aleutians could prevent the US from mounting a counterattack in the northern Pacific, while the Americans feared that the Imperial Japanese Navy Air Service would be able to launch bombing raids against the West Coast if the Japanese controlled the islands.
In the aftermath of the Doolittle Raid of 18 April 1942, the Japanese planned to extend their defensive perimeter: they would land at Port Moresby in New Guinea and occupy Nauru and the Ocean Islands with forces from the Solomon Islands, while they would also launch an attack on the Aleutians before assaulting Midway. In June 1942, the IJN 5th Fleet, commanded by Vice-Admiral Boshiro Hosogaya, occupied the Aleutian islands without much resistance; most of the native Aleuts had been sent to internment camps in Alaska by the US government in preparation for the invasion. The Americans issued propaganda calling Alaska a "death trap for the Jap", as the US Navy used its superiority in the region to harass the Japanese fleet. After the Battle of the Komandorski Islands on 27 March 1943, the Japanese were forced to give up their supplying of the Japanese forrces in the islands with surface ships, instead using submarines.
In May 1943, the Americans began a campaign to recapture the Aleutian Islands. On 11 May 1943, the Americans began their invasion of Attu, during which they faced heavy Japanese resistance; Colonel Yasuyo Yamasaki died while leading one of the last banzai charges of the war. Only 28 Japanese soldiers were taken prisoner at the end of the battle, none of them officers. Attu was secured by 31 May 1943, and the Japanese high command decided to cut its losses and order that Kiska be abandoned a week later. The Japanese evacuation was complete by 28 July, and it was so secretive that the Americans needlessly subjected Kiska to a full-scale assault in the middle of August. 92 Americans and Canadians were killed and 221 wounded by Japanese mines and friendly fire incidents during the capture of Kiska. Thereafter, the Aleutians served as an air and submarine base for the Americnas, using them for raids against the Home Islands. The first American air raid on the Kurile Islands was carried out by 8 Attu-based B-25 medium bombers on 10 July 1943.