It was a not very well-kept Washington family secret that Martha Washington had a sister who was black.

Ann Dandridge was the daughter of Martha Washington’s father, John Dandridge, and an unknown slave of mixed African and Native American blood. After John Dandridge’s death in 1756, Ann, who was a young girl at the time, went to live with George and Martha at Mount Vernon and was kept by them as a slave.

Why didn’t Martha free her little sister from slavery? If she had felt any resentment towards her half-sister, Martha could easily have sold or otherwise gotten rid of her, yet she didn’t. She kept her around, lived with her, let her children play with her, but did not set her free.

To Martha, this may have seemed like benevolence. After all, there was no place in 1759 Virginia society for a free black Dandridge female. Ann’s choices in life would have been very limited. She could perhaps have obtained a position as a servant girl to a rich family, but no white man of any substance would have married her. If she had found a black husband, he would most likely have been a slave; her dark-skinned children would have been perpetually at risk of enslavement. Martha may have felt it best to keep Ann enslaved and under her own protection.

So Ann lived at Mount Vernon with her half-sister and brother-in-law. What she did there is unknown, but she probably spent much of her time knitting or sewing in the parlor along with the mistress of the estate and the female house slaves. To visitors she would have seemed just another mixed-race servant, perhaps the mistress’s favorite.

Martha’s “protective” ownership of Ann was not foolproof. Sometime around 1780, Ann Dandridge bore a son, William. It appears that Martha’s son, an unsavory character named Jacky Custis, exerted the rights of a master over a slave; he fathered a child with Ann, who was his aunt as well as his property. Ann’s son William was both grandson and nephew to Martha Washington.

After giving birth to the child of Jacky Custis, Ann married a slave named Costin. The couple had four daughters, all of them nieces of Martha Washington, and all of them born slaves-for-life of the Custis estate. Yet William, her first child and Martha’s grandson, was legally regarded as free, by request of the mistress herself.

Once George and Martha were both dead and Ann was in her forties, she came into the possession of Martha’s granddaughter, Eliza Custis Law.

Eliza and her husband, Thomas Law, were uniquely sensitive to the plight of mixed-race people, for Thomas, before marrying Eliza, had been an official of the East India Company, and had three half-Indian sons.

Upon inheriting ownership of Ann Dandridge in 1802, the Laws freed her almost immediately. Five years later, they emancipated all Ann’s children, her grandchildren, and William Costin’s wife.

(Wiencek 84-86, 282-290)