Marching Orders: The Untold Story of How the American Breaking of the Japanese Secret Codes Led to the Defeat of Nazi Germany and Japan

by Bruce Lee

“I know from firsthand experience,” Whitlock says, “that from the fall of 1941 through the attack on Pearl Harbor we did not read any JN-25 codes. The first message we read of JN-25 on Corregidor was on March thirteenth, 1942. This message was the one in which the Japanese used the designator ‘AF’ to identify Midway. Nobody, including the British, with whom we worked closely, was reading JN-25 on a current basis up to the start of the war.”