Jean Cooper was an engine mechanic in the 393rd Bomber Squadron of the 509th Composite Group serving in both Wendover, Utah and Tinian Island in the Pacific. Cooper enlisted in the Army in 1943 after 2 1/2 years at Central Michigan University. After basic training at Miami Beach he was assigned to airplane mechanic school at Amarillo, Texas, before transferring to Chanute Field in Illinois for electrical training. Finally he was sent to Renton, Washington where he was introduced to the newly designed B-29 Superfortress.
His first assignment was as line mechanic with the 393rd Bombardment Squadron at Fairmont, Nebraska. This squadron formed the core of the 509th Composite Group when it was activated. Jean moved with the squadron to Wendover, UT and finally to Tinian Island where he worked as the engine mechanic on the #4 engine of the Enola Gay, the B-29 that dropped the first atomic bomb on Hiroshima, Japan.