Lieutenant Haddock was a member of Company C, 1st Battalion, 35th Infantry Regiment, 25th Infantry Division. On 28 November 1950, he led his platoon into a North Korean village and was ambushed. He was last seen trying to aid a wounded comrade. He was listed as Missing in Action and presumed dead on 31 December 1953. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Haddock was awarded the Purple Heart, the Combat Infantryman 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.