Corporal Duffy was a member of Weapons Company, 3rd Battalion, 1st Marines, 1st Marine Division. He was Killed in Action while fighting the enemy in the Punch Bowl area, Korea on 3 June 1951.

For his leadership and valor, Corporal Duffy was awarded the Bronze Star Medal with Combat Valor Device, 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.