Master Sergeant Vann was a member of Company C, 1st Battalion, 21st Infantry Regiment, 24th Infantry Division. He was taken Prisoner of War while fighting the enemy in South Korea on 5 July 1950, forced to march to North Korea on the "Tiger Death March", and died while a prisoner at Hanjang-ni, North Korea on 6 January 1951. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

For his leadership and valor, Master Sergeant Vann was awarded the Bronze Star Medal, the Purple Heart, the Combat Infantryman Badge, the Prisoner of War 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.