32. The Code Breaker Who Tricked the Japanese Into Revealing Their Intentions
Jimmy Doolittle’s bombing of Tokyo in the spring of 1942 gave the Japanese military a black eye. So they set out to draw the US Navy into a climactic battle in which they hoped to inflict a crushing defeat on the Americans. Evidence began piling up that the Japanese were gearing up for a major move, but nobody was sure about their target.
American cryptanalysts had cracked Japanese ciphers, and knew that they planned to attack a target codenamed “AF”. However, nobody knew what AF was. So Navy cryptanalyst Joseph Rochefort tricked the Japanese into showing their hand. Suspecting that AF was Midway Island, Rochefort directed Midway’s radio station to send an uncoded message, stating that its water purification system had broken down and that the island was running out of drinking water. 24 hours later, American code breakers intercepted a Japanese message to the effect that “AF” was running out of water.