After four days of carrier warfare near Midway Atoll, American dive bombers had already sunk three Japanese fleet carriers on June 4; on June 6 the fourth, Hiryu, succumbed and the Japanese fleet withdrew. The US lost the carrier Yorktown but the balance of naval power in the Pacific shifted decisively toward the Allies, ending Japan's six-month string of unbroken victories.
Admiral Chester Nimitz had a crucial advantage: American codebreakers had cracked Japan's naval code and knew Admiral Yamamoto's plan almost before his own captains did. Three US carriers lay in ambush for four Japanese carriers steaming toward what Yamamoto assumed would be an easy conquest of Midway Atoll.
June 4 delivered the decisive blow, when American dive bombers caught Japanese flight decks crowded with fueled, armed aircraft and turned three carriers into infernos within minutes. Hiryu survived that day's carnage and launched punishing counterstrikes that mortally wounded USS Yorktown, but American bombers returned to sink Hiryu itself. By June 6, as the Japanese fleet retreated, the once-dominant Imperial Navy had lost four fleet carriers and over 200 aircraft along with their irreplaceable veteran pilots.
Historians consider Midway the turning point of the Pacific War. Japan never again launched a major offensive; the initiative passed permanently to the United States, which spent the next three years pushing steadily toward Tokyo.