Merlin joined the Air Corps Reserve at aged 17 and was called to active duty in February 1944 when he turned 18. He trained as a gunner, assigned to an air crew and crossed the Atlantic in January 1945. He flew on seven combat missions in the ETO before returning to the States in June and beginning training on the B-29. He re-enlisted following the Japanese surrender, serving in Korea and Viet Nam- where he became a Green Beret, retiring in 1965.