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.
Saipan was the first objective in Operation Forager, the campaign to occupy the Mariana Islands that got underway at the same time the Allies were invading France in Operation Overlord. After a two-day naval bombardment, the U.S. 2nd Marine Division, 4th Marine Division, and the Army's 27th Infantry Division, commanded by Lieutenant General Holland Smith, landed on the island and defeated the 43rd Infantry Division of the Imperial Japanese Army, commanded by Lieutenant General Yoshitsugu Saitō. Organized resistance ended when at least 3,000 Japanese soldiers died in a mass gyokusai attack, and afterward about 1,000 civilians committed suicide.