The Battle of Saipan was an amphibious assault launched by the United States against the Empire of Japan during the Pacific campaign of World War II between 15 June and 9 July 1944. The initial invasion triggered the Battle of the Philippine Sea, which effectively destroyed Japanese carrier-based airpower, and the battle resulted in the American capture of the island. Its occupation put the major cities of the Japanese home islands within the range of B-29 bombers, making them vulnerable to strategic bombing by the United States Army Air Forces. It also precipitated the resignation of Hideki Tōjō, the prime minister of Japan.