Corporal Mireles was a member of Company D, 1st Battalion, 29th Infantry Regimental Combat Team. He was listed as Missing in Action while fighting the enemy near Hadong, South Korea, on 27 July 1950. He was presumed dead on 5 March 1954. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Mireles 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.