Corporal Greenwood was a light weapons infantryman with Company F, 2nd Battalion, 38th Infantry Regiment, 2nd Infantry Division. He was Killed in Action while withdrawing from the Chinese near Kunu-ri, North Korea, on 30 November 1950.

Greenwood was awarded the Purple Heart, the Combat Infantryman's Badge, 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.