Private First Class Simpson was a member of Company A, 1st Battalion, 5th Marines, 1st Provisional Marine Brigade. He was Killed in Action while defending his position at the Pusan Perimeter in South Korea on 3 September 1950.

Simpson 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.