U.S. Navy codebreakers had cracked Japanese naval ciphers, allowing Admiral Chester Nimitz to ambush a numerically superior fleet. Dive bombers from USS Enterprise and Yorktown caught Japanese carriers Akagi, Kaga, and Soryu refueling and rearming planes on deck, turning them into infernos within a ten-minute span. The Imperial Japanese Navy never recovered the initiative in the Pacific.
The Battle of Midway hinged on minutes and miscalculation. Japanese Admiral Chuichi Nagumo had just decided to re-arm his reserve aircraft with bombs for a second strike on Midway's airfield when scout reports revealed American carriers nearby, forcing a frantic, unfinished switch back to torpedoes. Flight decks were littered with fuel lines and ordnance when the American dive bombers arrived undetected, having been drawn to the fleet's wakes after a nearly disastrous, uncoordinated approach.
In roughly six minutes, Akagi, Kaga, and Soryu were transformed into blazing wrecks; Hiryu was hit and sank by nightfall. The U.S. lost the carrier Yorktown, but the trade was catastrophic for Japan, which lost four irreplaceable fleet carriers and hundreds of experienced aircrew.
The victory owed enormously to cryptanalysts at Station HYPO in Hawaii, who had broken enough of the JN-25 code to deduce that 'AF' — Japan's target designator — meant Midway, confirmed by a deliberately leaked false message about a water shortage there. Historians still call Midway the most consequential naval battle of the twentieth century.