Alaska was the only American soil on which ground fighting occurred during World War II; the Aleutian Islands Campaign began following the Japanese bombing of Dutch Harbor and seizure of Attu and Kiska islands in the Aleutian Chain in June 1942. The successful battle by the U.S. to retake Attu in May 1943 was proportionately one of the most costly amphibious assaults of World War II in the American and Pacific theaters in terms of American casualties suffered. The Japanese secretly evacuated Kiska in late-July 1943, several weeks prior to U.S. and Canadian forces seizing the island in mid-August 1943. At the end of the war, most Army installations throughout the state closed permanently or transferred to other agencies. Postwar emphasis turned to training.