During the Battle of Midway in June 1942, the Japanese had captured Attu and Kiska in the Alaskan Aleutian islands. Due to the terrible combat conditions in Alaksa, an American assault on the outposts could not be accomplished until May 1943. Until then, U.S. bombers shelled the islands in preparation for an invasion. On May 11, with overwhelming superiority in air, sea, and ground forces, American troops landed on Attu. For 18 days, U.S. forces faced some of the fiercest counterattacks of the war. Finally, on May 31 the island was secured.