Cletus was rejected for service in WWII because of a small kidney. He instead applied to the Civil Service, and was granted a commission by the Naval Department as a shipwright supervisor. He was assigned to the naval base at Pearl Harbor in July, 1943, where he worked repairing ships for 18 months. He assisted in the raising of the battleship Oklahoma, sunk by the Japanese on December 7, 1941. In February 1945, he was transferred to the naval base at Norfolk, Virginia, where he remained until his discharge in 1945.