The Battle of Midway is frequently referred to as "the turning point in the Pacific." After a series of losses, the United States won a decisive victory over the Japanese Imperial fleet. Damages to the Japanese carrier fleet were insurmountable and their momentum was broken. The Japanese were never able to replace the four aircraft carriers and 332 aircraft. Nor could they replace their top, combat tested, pilots, lost in the battle. After the Battle of Midway, the Japanese Navy fought defensively in the Pacific rather than offensively.
The Japanese had hoped to surprise the American military on Midway Island and claim this crucial location. However, American Navy cryptologists stationed in Hawaii had made some breaks into the Japanese Navy Fleet Code, known to cryptanalysts as JN-25B. Although they were breaking less than 15% of JN-25, CDR Rochefort, the Officer-In-Charge of the cryptanalysts, came to believe that the Japanese were planning to attack a target codenamed AF. Rochefort believed AF referred to Midway. With the approval of RADM Nimitz, instructions were given to the Marines on Midway to send a plaintext message complaining about the lack of fresh water. Two days later, 12 May 1942, a JN-25 message was decoded stating: “AF is short of water.”
Knowing Midway would be attacked, the U.S. Navy and Marines were able to adjust their forces and combat the attack head on. Although the battle raged for portions of three days, and significant numbers of U.S. and Japanese lives were lost, the Americans defeated the Japanese fleet. The U.S. lost 307 men, one carrier (the Yorktown,) one destroyer, and 147 aircraft. The Japanese lost 2,500 men, four carriers, one heavy cruiser, and 332 aircraft.