Corporal O'Hara was a Browning Automatic Rifleman with Company E, 2nd Battalion, 5th Infantry Regimental Combat Team. He was Killed in Action while fighting the enemy near Kumji-ri, North Korea, on 4 April 1951.

O'Hara 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, the Republic of Korea War Service Medal and the Army of Occupation Medal (Germany).