Rear-Admiral Donald Mac Showers joined the U.S. Navy’s codebreakers at Pearl Harbor in 1942 and went on to serve three decades in the American intelligence community. Today, he talks about the contribution of codebreaking to the defeat of Japanese naval forces at Midway in 1942, and he reveals how cryptanalysts helped U.S. forces locate and kill Admiral Isoroku Yamamoto, the mastermind of the Japanese attack on Pearl Harbor.