ary Postell, Birchtown, was the slave of a wealthy South Carolina planter when the war began. She managed to get herself and her children away from him, and they claimed freedom behind the British lines. Her certificate of freedom was taken from her, however, by a White person who pretended he wanted to see her papers. When Charleston surrendered to the Americans, she went to St. Augustine, Florida, with her husband and family, as servants to Jesse Gray. There, Gray claimed she was legally his slave, and sold her to his brother Samuel.

Samuel and Jesse Gray emigrated to Nova Scotia, taking Mary and her daughters along. At some point, Samuel sold Mary back to Jesse. She became very afraid that Jesse Gray would sell her away from her children. One night, she escaped with them from his house. Gray went to court to prove he owned her; then, to punish her, he took her down the coast to Argyle, where he sold her to William Maugham for one hundred bushels of potatoes. Ignoring Mary's desperation and heartbreak, he sold her daughter Flora to John Henderson, keeping another daughter, Nell, as his own property. Such was the terrible reality of slavery in Nova Scotia.