In 1943, at the age of 17, Leonard graduated from The University of Detroit High School, and tried to join the Marines, but was rejected because of poor vision. He was subsequently drafted and assigned to the Seabees, the fighting construction battalion of the United States Navy. He served for a little more than a year and a half in the Admiralty Islands and the Philippines before returning home in January of 1946. He was assigned to a ship for six and a half months and was discharged from the Navy in June of that year.
