Corporal O'Connor was a member of the 4.2" Mortar Company, 1st Marines, 1st Marine Division. He was Killed in Action while fighting the enemy in Korea on 9 June 1951.

O'Connor was awarded 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.