Second Lieutenant Guion was the pilot of an AD-3 Skyraider dive bomber with Marine Attack Squadron 121, Marine Air Group 12, 1st Marine Air Wing. On 8 October 1952, while on a combat mission over North Korea, his aircraft was struck by anti-aircraft fire and crashed. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Guion was awarded the Air Medal, the Purple Heart, the Combat Action Ribbon, the Korean Service Medal, the United Nations Service Medal, the National Defense Service Medal, the Korean Presidential Unit Citation and the Republic of Korea War Service Medal.