Born circa 1846, Hart was raised in Roane County in western Virginia, where she learned to be a skilled horse rider and an excellent shot with both rifles and pistols. In 1861 her brother-in-law William Price, a Confederate supporter, was abducted and killed by Union soldiers. The act drove Hart into a fury and just days later she joined the Moccasin Rangers, a pro-Confederacy guerrilla regiment led by Perry Conley.
For nearly two years Hart worked for the Moccasin Rangers as a spy and a scout, posing as a farm girl to gather intelligence. She saved the lives of a number of wounded Confederate soldiers by hiding them with sympathizers. She also personally led several cavalry raids against federal outposts. After one such skirmish she was briefly captured, but she persuaded the Union soldiers to let her go based on the fact she was a woman.
Conley died in the summer of 1862, and with his loss the Moccasin Rangers disbanded, although Hart continued to spy on Union movements. Her work prompted federal officials to put a large price on her head, ultimately leading to her capture and imprisonment in a Union camp. She did not remain in captivity long however, as she seduced a guard to steal his gun, killed him and escaped on horseback. A week later Hart returned to the Union camp with 200 Confederate Cavalrymen, capturing a number of federal officers with minimal resistance.
Hart married a fellow Moccasin Ranger named Joshua Douglas and after the war they had two sons. Hart died in 1902 and is buried on Manning Knob in Greenbrier County.