During the first months of the war in the Pacific, the Navy OP-20-G group broke the very complex Japanese Imperial Navy JN-25 code. In decrypted transmissions, they saw the code “AF” mentioned several times and thought it might mean an attack was coming on that location. To affirm it was Midway Island, they used a communications cable that ran on the bottom of the ocean and had the Navy send a “in the clear” radio message that said, “water distillation plant damaged…send fresh water.” The JN-25 code then produced a message saying, ”AF needs fresh water.” They knew where and when the attack would happen as well as enemy strength because of SIGINT. It helped win the Battle of Midway and became one of the greatest intelligence coups in naval history.