When he was 11 years old, Washington inherited 10 slaves from his father’s estate. He continued to acquire slaves — some through the death of family members and others through direct purchase. Washington’s cache of enslaved people peaked in 1759 when he married the wealthy widow Martha Dandridge Custis. His new wife brought more than 80 slaves to the estate at Mount Vernon. On the eve of the American Revolution, nearly 150 souls were counted as part of the property there. In 1789, Washington became the first president of the United States, a planter president who used and sanctioned black...