Corporal Whalen was a member of Company B, 2nd Chemical Mortar Battalion, U.S. Army. He was listed as Missing in Action while fighting the enemy near Unsan, North Korea, on 2 November 1950. He was presumed dead on 31 December 1953. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Whalen was awarded the Purple Heart, 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.