In 1842, one of the most respected residents of Washington, D.C. died in his sleep at age 62. Prominent peers had previously described him as “upright” and “honorable”; his obituary stated that he possessed “unflinching integrity.” A posthumous portrait of him shows a genteel, serious figure in a top hat and fine clothes, turning to gaze at the viewer through spectacles.

The man’s name was William Costin, and he was listed in the 1820 census as “colored.” He was also probably Martha Washington’s grandson—the child of her son from her first marriage, John “Jacky” Parke Custis, and an enslaved woman.

Over the past 20 years, a number of historians (including Mount Vernon research historian emerita Mary Thompson) have argued that Costin may have been a blood relation of the first lady. When the first account of Costin’s life was published in a government report in 1871, the focus was on his mother, a woman identified as Ann Dandridge. The report stated that Dandridge’s grandfather was Cherokee, and her mother was an enslaved woman, while her father was John Dandridge—also Martha’s father.

First Family: George Washington's Heirs and the Making of America

Award-winning historian Cassandra A. Good shows how the outspoken step-grandchildren of George Washington played an overlooked but important role in the development of American society and politics from the Revolution to the Civil War.

This story, highlighting Ann Dandridge as Martha’s half-sister, has been widely repeated in history books but is almost certainly untrue. The dates don’t line up, and there is no sign of an Ann Dandridge at Mount Vernon; perhaps two women’s stories were conflated. Instead, the latest research about Costin’s mother indicates she was enslaved by the Custis family (probably living on their Tidewater Virginia plantations) and went by Ann or Nancy. She married twice, taking her husbands’ last names, Costin and Holmes, in turn.

The case for Costin’s father is much clearer. Drawn together, evidence including Costin’s manumission (release from slavery) by a Custis relation, his choice of names for his children, his ownership of Washington and Custis family heirlooms, and oral histories from his family strongly suggest he was Jacky’s son. Indeed, Costin’s daughter directly identified Jacky as her grandfather in the late 1860s.

George Washington was Martha’s second husband. She married her first husband, Daniel Parke Custis, a prominent Virginia landowner and enslaver, in 1750. They had four children, two of whom survived childhood: Jacky and Martha “Patsy” Parke Custis. In 1757, Daniel died, leaving Martha an exceedingly wealthy widow. In early 1759, she married Washington and moved with Jacky and Patsy to Mount Vernon. (Historians believe that Washington was likely sterile; Martha never bore him any children.) Patsy died at age 17, but Jacky lived long enough to marry and have four surviving white children with his wife, Eleanor Calvert Custis: Martha, Eliza, Nelly and Wash Custis. Just a year before his death in 1781, Jacky apparently fathered another child by an enslaved woman: Costin, who later took his stepfather’s last name.

Details of Costin’s early life are difficult to pin down. But historical records suggest he and his mother were enslaved by the Custis estate and inherited by Jacky’s son-in-law Thomas Law, likely as part of his wife Eliza’s dowry. Law freed both Costin and his mother in 1802, shortly after Martha Washington’s death. Costin then married Philadelphia Judge, the enslaved sister of Ona Judge, who served as Martha’s personal maid before she famously fled to freedom in the 1790s. Law and Eliza had inherited Philadelphia from the Custis estate upon Martha’s death, so it’s possible Costin met her in their household.

A circa 1859 watercolor of Martha Washington
A circa 1859 watercolor of Martha Washington Smithsonian American Art Museum
Costin's likely father, John "Jacky" Parke Custis
Costin's likely father, John "Jacky" Parke Custis Public domain via Wikimedia Commons

In 1807, Law freed Costin’s maternal half-siblings (four from his mother’s first marriage and two from her second), as well as his wife and two young daughters, Louisa and Ann. Costin and Philadelphia went on to have five more children, all born free. In keeping with Custis family tradition, Costin gave all seven of his children the middle name “Parke.” He even gave one son the middle name “Custis Parke.” The young man later went by “Custis.”

Costin was also in close contact with Jacky’s four white children. Working as a paid carriage driver in D.C., he ran errands for Nelly and Eliza. In 1809, Eliza called him “my faithful ‘tho humble friend Billy”; in 1824, Wash signed a quick note to Costin “Your friend.”

While Costin was never wealthy, he rose above his humble beginnings to become one of D.C.’s most prominent Black residents. Around 1818, he was hired as a porter for the Bank of Washington, entrusted with carrying large sums of money. His salary was sizable enough that he was able to sign a 99-year lease for a lot now occupied by the Library of Congress’ Jefferson Building. In 1842, Costin insured the two-story house he built there, as well as the furniture within it, for $250 (around $9,000 today). Among his possessions were several objects that had been owned by George and Martha Washington at Mount Vernon, including a valuable French porcelain figure similar to one in the estate-turned-museum’s collection, a Windsor chair and a vase—all further evidence of his close ties to the Washington and Custis families.

An 1824 letter from Wash to Costin
An 1824 letter from Wash to Costin The George Washington Presidential Library at Mount Vernon

Costin’s neighbors were mostly small tradesmen and government clerks, the majority of whom were white and some of whom enslaved people. Over the next 20 years, Costin amassed enough wealth to buy several more lots and houses. By the 1840s, he was one of the most prolific Black property owners in the nation’s capital.

Admitted to the upper echelons of D.C. society, Costin promoted causes related to the city’s growing Black community. In the 19th century, work opportunities and less restrictive racial codes (compared with neighboring Virginia) attracted an increasing number of free Black people to D.C. In 1800, nearly 30 percent of the city’s population was Black, but only around 20 percent of these individuals were free. By 1840, the city was still 30 percent Black, but 65 percent of these residents were free. The city had many race-based restrictions that made life more difficult for Black Washingtonians, including limits on the type of jobs they could have, so the community formed charitable organizations to help.

Elizabeth "Eliza" Parke Custis Law
Elizabeth "Eliza" Parke Custis Law Public domain via Wikimedia Commons
Eliza's husband, Thomas Law
Eliza's husband, Thomas Law Public domain via Wikimedia Commons

Costin served as the first president of the Resolute Beneficial Society, formed in 1818 to support the Black community on issues ranging from education to burials. He was also a founding member of D.C.’s first independent Black church, Israel Metropolitan Christian Methodist Episcopal Church (still in operation today), and belonged to the city’s first Black Freemasonry organization.

In addition to securing his own family’s freedom, Costin purchased and freed three enslaved people from his probable half-brother, Wash, in 1827. He raised one of them—a 4-year-old child named Montgomery Parke (possibly related to the Custises)—in his own family.

Opportunities to participate in antislavery efforts in D.C. were limited, as most activists were located further north, but Costin did take one bold step: a nonviolent protest of a new racist law in the city in 1821. The law required all free Black people to show written evidence of freedom, ask three white residents to vouch for their character and post a $20 bond that could be forfeited if they failed to conduct themselves properly or became impoverished. Those who refused could be fined, jailed or even expelled from the city—but Costin was apparently willing to take this risk. He had been living as a free man for nearly 20 years and would not bow to these new rules. The city fined him, but he didn’t back down, instead appealing to the D.C. Circuit Court.

Costin and his lawyer, Supreme Court clerk Elias Boudinot Caldwell, didn’t just argue against the law. As Caldwell told Judge William Cranch, “The Constitution knows no distinction of color. … All who are not slaves are equally free [and] equally citizens of the United States.” As citizens, free Black people had the right to live in any state and could not be required to post bond like someone convicted of a crime. While Caldwell acknowledged that free Black people, like free white Virginians who didn’t own property, couldn’t vote or serve on juries, he argued they still deserved “all the privileges and immunities of citizens”—protections later guaranteed under the 14th Amendment.

Eleanor "Nelly" Parke Custis Lewis
Eleanor "Nelly" Parke Custis Lewis Public domain via Wikimedia Commons
George Washington "Wash" Parke Custis
George Washington "Wash" Parke Custis Library of Congress Prints and Photographs Division

Whether free Black people were in fact citizens was a matter of debate. In 1820, when Missouri was admitted to the union as a slaveholding state, Congress had discussed but never resolved the issue. By identifying his community as citizens, Costin used his court case to make a bold statement about civil rights.

Ultimately, Costin won his case but lost on principle. Cranch ruled that nowhere in the Constitution were states barred from restricting political rights based on race. Besides, he said, “I can see no reason” why a state can’t “require security for good behavior from free persons of color,” “vagrants” and “persons of ill-fame.” Cranch’s only issue with the law was that it was being applied retroactively to free Black people who had lived in the city for years, many of whom were “useful members of society” who paid taxes. It surely helped Costin’s case that he was so highly regarded in D.C.

A portrait of the Washington family
A portrait of the Washington family, depicting (left to right) Wash Custis, George Washington, Nelly Custis, Martha Washington and an enslaved man Public domain via Wikimedia Commons

Indeed, even after Costin’s sudden death in his sleep in May 1842, he was praised as a model citizen whose example showed why African Americans were deserving of equal rights. That June, Representative (and former President) John Quincy Adams delivered an impassioned speech to Congress, using Costin as the centerpiece of his argument against the addition of the word “white” to D.C. voting qualifications. Why should “a good citizen, a good husband, good father and kind neighbor” like Costin be barred from voting because of the color of his skin? As one Black newspaper noted, Costin and others like him “give the lie to the aspersions of slavery and caste.”

No records indicate that Costin was ever publicly acknowledged as a member of the Custis family during his lifetime. He could not lay claim to the fame his likely half-siblings built as the adopted grandchildren and heirs of America’s first president. But that fact didn’t render him powerless; in fact, in his advocacy for D.C.’s Black community, he did far more than most white Americans, including Martha’s other grandchildren, to advance the ideals of liberty and equality that George Washington fought for in the American Revolution. In that way, then, Costin may have been the true inheritor of the finest aspects of Washington’s legacy.

Get the latest History stories in your inbox?

Click to visit our Privacy Statement.