but I'd never heard this about him:
During World War II, McMahon was a fighter pilot in the United States Marine Corps serving as a flight instructor and test pilot. He was a decorated pilot and was discharged in 1946, remaining in the reserves.
After college, McMahon returned to active duty. He was sent to Korea in February 1953. He flew unarmed O-1E Bird Dogs on 85 tactical air control and artillery spotting missions. He remained in the Marine Corps Reserve, retiring with the rank of Colonel in 1966 and was then commissioned as a Brigadier General in the California Air National Guard.