After attempting to enlist in the U.S. Marine Corps during World War II but being pulled out by his father "because I was underage", Colan at "18 or 19" enlisted in the Army Air Corps. Originally scheduled for gunnery school in Boulder, Colorado, plans changed with the war's sudden end. "I was going to be an aerial gunner. A bomber. But it never materialized", he recalled in 2001. After training at an Army camp near Biloxi, Mississippi, he joined the U.S. forces in the Philippines. There Colan rose to the rank of corporal, drew for the "Manila Times", and won an art contest.