John Knoepfle was attending Xavier University in Cincinnati, Ohio when the Japanese attacked Pearl Harbor. He joined the Navy's V-12 program for training officers, and in 1944 was assigned to the USS Deuel, an attack transport ship. He served as a small boat officer, and in that capacity led eight Higgins Boats (LCVPs) onto the beach at Iwo Jima in February1945. He was wounded while his ship supported operations on Iwo Jima, recovered and was still with the ship for the Okinawa campaign when his injury flared up. He was sent back through a series of naval hospitals in search of a surgeon who could perform a very complicated operation. That finally happened at Great Lakes Naval Training Center, where he was treated and later released in 1946.