T/Sgt. Sheehan served in World War II as a member of the 301st U. S. Bomb Group, 352nd Bomb Squadron, 8th U.S. Army Air Force, as a tail gunner on a B-17 bomber. He was shot down on 22 July 1944 after his craft completed a bombing run over the Ploesti Oil Fields. He parachuted to safety but was ultimately captured and spent the remainder of the war as a prisoner of the Germans.