Hiryu, a 20,250-ton aircraft carrier built at Yokosuka, Japan, was completed in July 1939. Active throughout the first six months of the Pacific War, she took part in the December 1941 Pearl Harbor attack as well as operations in the East Indies and Indian Ocean area. On 4 June 1942, during the Battle of Midway, Hiryu's aircraft inflicted serious bomb and torpedo damage to USS Yorktown (CV-5), causing her abandonment. Later that day, Hiryu was hit by U.S. carrier dive bombers. Though she remained underway for a time, she had been fatally damaged. Abandoned early the following morning, Hiryu sank at about 0900 on 5 June, the last of four Japanese aircraft carriers to be lost in the battle.