First Lieutenant Hartman was a member of Battery A, 52nd Field Artillery Battalion, 24th Infantry Division. He was taken Prisoner of War while fighting the enemy in South Korea on July 5, 1950, forced to march to North Korea on the "Tiger Death March", and died while a prisoner at Hanjang-ni, North Korea on March 8, 1951. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.