Private Gillespie was a member of the 23rd Infantry Regiment, 2nd Infantry Division. He was seriously wounded by the enemy in North Korea on 21 October 1951 and died of those wounds later that day.

Gillespie was awarded the Purple Heart, the Combat Infantryman's Badge, 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.