In 1943, Smyth enlisted in the U.S. Marine Corps and was assigned to the V-12 Navy College Training Program at Pennsylvania State University. He played for the 1943 Penn State Nittany Lions football team. Smyth later served in the Pacific Theatre of World War II and participated in the first day landings in the Battle of Iwo Jima. In the fall of 1945, he played for the Marines All-Star football team. He returned to Cincinnati after the war and played for the 1946 Cincinnati Bearcats football team that compiled a 9–2 record.
