Private First Class Yellen was a member of Company E, 2nd Battalion, 7th Marines, 1st Marine Division. He was seriously wounded while fighting the enemy at the Chosen Reservoir, North Korea and died of those wounds on 1 December 1950.

Yellen 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.