In October 1952, the owner of the three-year-old filly, whose original name was “Ah Chim Hai,” which means “Morning Flame,” sold her to Lieutenant Eric Pedersen of the 5th Marine Regiment’s Recoilless Rifle Platoon so that he could buy a prosthesis for his sister, who had lost a leg in a land mine explosion.
Pedersen was willing to pay $250 for her because he needed help supplying his positions in mountainous terrain that had proven too difficult for motorized vehicles. To prepare her for her new job, Technical Sergeant Joe Latham put her through “hoof camp,” a boot camp for horses where she learned to accept the chaos and noise of battle and to carry the 24-pound ammunition shells that the Marine’s 75mm recoilless rifles required. The filly also learned how to step over communication lines and barbed wire, and she learned to respond to a shouted ‘Incoming!’ by running to a bunker or trench and lying down. By the time she was ready for service, she had learned to navigate all the service roads between the supply depot and the front lines by herself.
Once she was named after them, Reckless became "one of the men." She followed them everywhere, sleeping with them in their tents and eating with them in the mess hall. Reckless ate bacon, scrambled eggs and coffee for breakfast, and she liked to snack on candy bars and Coca-Cola. She even drank beer with her fellow Marines.
Reckless carried supplies to the front and evacuated wounded Marines back down the slope for medical treatment without a human escort. On a single day in March 1953, when the unit was entrenched at a place called Outpost Vegas, so named because it would be a gamble to hold, Reckless made 51 rounds trips through a no-man’s land of rice paddies and steep hills. She delivered almost 9,000 pounds of ammunition from the supply point to the gun teams and probably saved the lives of the dozens of men she brought back to the medical unit.
Reckless received two shrapnel wounds that earned her a pair of Purple Hearts. She was given a battlefield rank of corporal in 1953 and promoted to sergeant after the war, when she was also awarded a Marine Corps Good Conduct Medal. She was the only animal ever awarded an official rank in the Marine Corps.