First Lieutenant Gilles was the pilot of a F-94B Starfire fighter with the 319th Fighter Interceptor Squadron, U.S. Air Force. On the night of 8 July 1953, he was returning from a mission over North Korea, when his aircraft struck a mountain a mile and a half west of Suwon Airfield (K-13), South Korea.

Gilles was awarded 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.