The Japanese felt the Aleutian Islands could be a launching point for an attack on Japan by the United States. Sending two aircraft carriers to Alaska, the Japanese used the Aleutians to be a decoy to pull remaining forces away from Pearl Harbor. Then, a massive naval force from Japan would move in to attack Midway Island. The United States had broken the Japanese code and knew of the plan. Sending only enough resources to defend Alaska, the remaining Pacific Fleet was sent to greet the Japanese force and defeat it.
June 3rd and 4th of 1942, the Japanese attacked Dutch Harbor. The raids took 43 lives and wounded 64 more. June 6th and 7th saw virtually no resistance from the United States forces leaving Kiska and Attu Islands to be taken easily. The Japanese really had no need of the islands, once they lost Midway, other than to ensure that the Americans had no way to launch an offensive against their homeland. So they stayed.
The Americans monitored the waters off Alaska very closely. With Japan on our soil in the islands, there was a very real threat to the mainland of Alaska of an attack from the Bering Sea. A Japanese fleet was sighted on three occasions in the waters between St Lawrence and Pribilof Islands in June of 1943 and placed a sense of urgency on the plans to re-take Kiska and Attu Islands.
An attack was planned on Kiska, after moving American forces onto nearby islands. The Army engineers made short business of building runways for the fighters to take off from, even though they were bombed by Japanese fighters sent out from Kiska as they worked. It was decided that Attu would be re-taken first when it was determined that the troops on Attu numbered 500 compared to the 9000 thought to be on Kiska. What was meant to be a three day battle, turned into weeks. After the Japanese troop numbers on Attu was raised to 1500, more troops were called in to assist in the first attack. They were sent from the sunny, warm shores of California, dressed in their desert uniforms. A great many of the injuries from the long attack on Attu, were from weather related injuries from lack of proper clothing and footwear. May 29 ended the attack that began May 11. Americans reported 2,351 dead Japanese. The United States force totaled more than 15,000 men, with 549 killed, another 1,148 wounded, and about 2,100 men with disease and non-battle injuries.
Now, on to Kiska. The American troops were better equipped to handle the weather, with parkas and arctic boots. The estimation of Japanese on Kiska was increased and the plan was to land with over 34,000 troops including 5,500 Canadians. Good thing since they were so off on their counts of Japanese on Attu Island! Landing on August 15th, the troops headed for the hills unopposed, but expecting the same as was encountered on Attu, they felt the Japanese were dug in. The Japanese had in fact, vacated the island in July! The troops lost to this battle were from friendly fire and a navy vessel hitting a mine, totaling just over 300.
There had actually been talk of attacking Japan from the Aleutian Islands, but the truth of re-taking the islands was simple. It was a blow to the United States ego to have Japanese on American soil in the Alaskan Aleutian Islands. The Forgotten War would not be forgotten with the establishment of the 134-acre Aleutian World War II National Historic Area on Amaknak Island in the Aleutian Island chain.