Sergeant Reckless was a mare of Mongolian Horse breeding. Out of a racehorse dam, she was purchased by the United States Military in October 1952 from a Korean stableboy at the Seoul racetrack who needed money to buy an artificial leg for his sister. She was trained as a pack horse for the 5th Marine Regiment, 1st Marine Division.
She quickly became part of the unit and was allowed to roam freely through camp, entering the Marines' tents, where she would sleep on cold nights, and was known for her willingness to eat nearly anything, including scrambled eggs, beer, Coca-Cola and, once, about $30 worth of poker chips.
Sgt. Reckless was a remarkably intelligent and charismatic animal who was known for her ability to learn supply routes - on which she carried up to 9 24lb shells - after only a few trips. She served a career of 9 months and was highly decorated with a rank of corporal and later Sergeant, earning two Purple Hearts and a Marine Corps Good Conduct Medal amongst other honors for her service. She was highlighted for her incredible achievement in the Battle for Outpost Vegas where she completed 51 unsupervised resupply trips to multiple frontline units. On completing her service, she was retired to the United States after the war.