Private First Class Johnston was a member of Company D, 2nd Battalion, 7th Marines, 1st Marine Division. He was Killed in Action while fighting the enemy near Chorch-Tong, Korea along the Western Outposts on 24 July 1952.

Johnston was awarded the Purple Heart, the Combat Action Ribbon, 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.