Private Rethmeier was a Heavy Weapons Infantryman with the 35th Infantry Regiment, 25th Infantry Division. He was Killed in Action while fighting the enemy on Hills 717 and 682 in North Korea on 7 September 1951.

Rethmeier 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.