He is the eighth living recipient to be awarded the Medal of Honor for actions in Iraq or Afghanistan.

Carpenter served as an Automatic Rifleman with Company F, 2d Battalion, 9th Marines, Regimental Combat Team-1, 1st Marine Division (Forward), I Marine Expeditionary Force (Forward). In July 2013, he was medically retired as a Corporal due to his wounds.

Carpenter is credited with attempting to shield a fellow Marine, Lance Cpl. Nick Eufrazio, from Plymouth, Massachusetts, from a grenade blast on a rooftop security post in combat operations near Marjah, Helmand Province, Afghanistan on 21 November 2010.

Both Marines survived the blast but suffered major injuries. Carpenter lost his right eye and most of his teeth. His jaw and right arm were shattered and he has undergone dozens of surgeries.