In 1830 Richard Walpole Cogdell, a husband, father, and bank clerk in Charleston, South Carolina, purchased a fifteen-year-old enslaved girl, Sarah Martha Sanders. Before her death in 1850, she bore nine of his children, five of whom reached adulthood. In 1857, Cogdell and his enslaved children moved to Philadelphia, where he bought them a house and where they became, virtually overnight, part of the African American middle class. An ambitious historical...