The Rev. Calvin Dill Wilson (1857–1946) was a Presbyterian minister and author. His book 'Black Masters,' first published in 1904, explore the history of wealthy free African-Americans who became slave-owners. According to Wilson's research, there were around 6,200 black slave-holders in the years before the Civil War, who owned some 18,000 slaves. By owning their families, free colored men and women could protect them against oppressive local laws. The earliest documentary evidence of such a transaction dates from 1724, in Boston, Massachusetts while most of the cases discussed here concern the states of Louisiana, Maryland, Mississippi and South Carolina.