Captain Brunnert was a veteran of World War II. In Korea, he was a Roman Catholic Chaplain assigned to Headquarters Company, 32nd Infantry Regiment, 7th Infantry Division. He was taken Prisoner of War while tending to the wounded and dying near Changjin Reservoir, North Korea on 2 December 1950 and died of wounds while a prisoner on 20 December 1950. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Brunnert was awarded the Purple Heart, the Prisoner of War Medal, 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 World War II Victory Medal.