Private Mariano was a member of the 32nd Infantry Regiment, 7th Infantry Division. He was Killed in Action while fighting the enemy in North Korea on 26 April 1951.

Mariano was awarded the Purple Heart, the Combat Infantryman's Badge, the Good Conduct Medal, 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.