Private First Class Bartnick was a member of Company K, 3rd Battalion, 31st Infantry Regiment, 7th Infantry Division. He was listed as Missing in Action while fighting the enemy during the battle for the Chosin Reservoir in North Korea on 12 December 1950. He was presumed dead on 31 December 1953. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Bartnick was awarded the Purple Heart, the Combat Infantryman's Badge, the Good Conduct Medal, 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.