@foxnews: Six U.S. presidents served in the Navy before becoming commander-in-chief. From John F. Kennedy's service aboard the PT-109 to George H. W. Bush's 58 combat missions as a Navy pilot, these future presidents served in roles spanning aircraft carriers, submarines, and naval aviation. Five served in the Navy during World War II, while Jimmy Carter entered the U.S. Naval Academy in 1943 and went on to serve as a submarine officer after the war. Swipe to learn about the six presidents' Navy service. Happy 251st birthday, U.S. Navy!