When the U.S. entered World War II, Stewart was drafted into the Army but was rejected because he was underweight for his height. He worked with colleagues to put on the necessary pounds, and successfully enlisted with the Air Corps. He was stationed at Moffett Field, California as an enlisted man. During his nine months of training at that base, he also took extension courses with the idea of obtaining a commission...His college degree and extensive flight time played to his favor, and he received his commission after the attack on Pearl Harbor. Because he had logged over 400 hours as a civilian, he was permitted to take basic flight training at Moffett and earned his pilot wings. During the next nine months, he instructed in AT-6, AT-9, and B-17 aircraft and flew bombardiers in the training school at Albuquerque, N.M. In the fall of 1943, Stewart went to England as Commanding Officer of the 703d Bomb Squadron, equipped with B-24s. He began flying combat missions and on March 31, 1944, was appointed Operations Officer of the 453rd Bomb Group and, subsequently, Chief of Staff of the 2nd Combat wing, 2nd Air Division of the 8th Air Force. Stewart ended the war with 20 combat missions. He remained in the USAF Reserve and was promoted to brigadier general on July 23, 1959. He retired on May 31, 1968.