The Epidemic of 1793

Yellow fever struck Philadelphia in August 1793. At the time, the vibrant port city and capital of the young United States was home to 50,000 Americans. By November, ten percent of them would be dead. A virus endemic to tropical regions, yellow fever traveled to Philadelphia in the bloodstreams of refugees from the Haitian Revolution. From there, mosquitoes teeming in the summer heat transmitted it from person to person as doctors struggled to contain a disease that, at its peak, killed one hundred people a day.[1]

The death toll and devastation reminded Dr. Benjamin Rush (class of 1760) of the Black Plague. “It comes nearer to it than any disease we have ever before had in this country,” he wrote during the first weeks of the epidemic.[2] A signer of the Declaration of Independence and the nation’s preeminent physician, Rush diagnosed the city’s first case of yellow fever in August. Symptoms progressed rapidly, from chills, high fevers, and headaches to delirium, cold hands and feet, and “a feeble slow pulse.”[3] Eyes “at first suffused with blood” before turning yellow as liver and kidney function failed and victims vomited blood and “black matter.”[4] Neither common fever remedies (wine and sweating) nor Rush’s own prescriptions (bleeding and purging) had any effect.[5] Some patients died in a matter of hours. Few survived more than four days.

“It not only mocks the power of medicine,” the doctor wrote of the disease, “but has spread through several parts of the city remote from the spot where it originated.”[6]

With the plague spreading rapidly, Rush advised Philadelphians to leave the city: “There is but one preventative that is certain,” he told his patients, “and that is ‘to fly from it.’”[7] Twenty thousand residents did just that, with government officials, affluent families, and any man or woman with the means to leave fleeing the city. The poor—including large numbers of African Americans—were left behind to fend for themselves.[8] Rush stayed behind as well to tend to those who remained, though he wasn’t optimistic about his chances of success.

“Tell the whole village of Princeton to pray constantly and fervently for us,” he wrote his wife Julia, a member of Princeton’s distinguished Stockton clan, who had been visiting family in New Jersey when the disease struck.[9] Only God could save them, “for vain – vain now is the help of man.”[10]

Yet Rush did have help in Philadelphia. Across the city, African Americans (whom many white Americans wrongly assumed to be immune to the disease on account of prejudiced ideas of racial difference) served as nurses, caretakers, and gravediggers in large numbers.[11] The city’s “African brethren” were “indefatigable,” Rush said, even as many of them succumbed to the disease themselves in the course of their labors.[12] But the doctor was most personally indebted to Marcus Marsh, a former slave who would become the famous physician’s most trusted medical assistant during the epidemic.

Benjamin Rush

Portrait of Benjamin Rush (class of 1760), physician and Founding Father.

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“I cannot tell you how much we all owe to Marcus”

Marcus Marsh was born into slavery on April 1, 1765, on the Stockton family’s Morven plantation in Princeton.[13] After his mother’s death, the lady of the house—poet Annis Boudinot Stockton—who was nursing her own child at the time, also nursed the infant Marsh, raising him (she said) “almost as my own son.”[14]

The “almost” was key. As a slave, Marcus Marsh was human property with no rights, as New Jersey would not pass a gradual emancipation law until 1804. But in 1781, Annis manumitted Marsh after the death of her husband Richard Stockton. A free man, Marcus Marsh went to live and work in the home of Benjamin Rush and his young wife Julia (Annis and Richard’s daughter), whom Marsh would have grown up alongside at Morven.

Benjamin Rush was an early critic of slavery and the slave trade, arguing that Africans were white Americans’ moral and intellectual equals in a 1773 pamphlet, though he himself owned a slave: William Grubber, whom Rush described as a “native African” he’d reformed from drunkenness, swearing, and other “vices.”[15] Rush purchased him from a ship’s captain in Philadelphia, where Grubber had likely gained his experience as a sailor—and, apparently, a sailor’s foul mouth.[16] Throughout the 1780s he was hired out to work on other ships, spending long periods at sea; when he returned to Philadelphia, Rush recorded in his papers, Grubber “always made my house his home.”[17] The money Grubber earned also made its way to Rush’s home: as an enslaved man, he couldn’t own property.

Rush justified his practices by asserting that Grubber’s labor was “a just compensation for having paid for him the full price of a slave for life.”[18] In 1788, the doctor calculated that six more years of service would be sufficient repayment, and promised to free Grubber in 1794; Rush would ultimately free him before then, by 1793 at the latest.[19] William Grubber, however, would enjoy his freedom for only a few years before his death in 1799.[20]

Aside from his letter of manumission and brief account of Grubber’s death, Rush rarely mentioned the enslaved man in his letters or papers. Marcus Marsh, on the other hand, appeared frequently. In 1793, 28-year-old Marsh’s presence proved vital to the middle-aged physician as he endeavored to treat victims of the yellow fever epidemic in Philadelphia. At times, Rush referred to his assistant in patronizing terms, praising “the fidelity and affection of our humble black friend.”[21] But the doctor clearly respected Marsh’s skill and intelligence.

“I told you formerly how universal his talents were,” Rush wrote Julia in October 1793.[22] Marsh was “equal to any apothecary in town,” more competent even than some physicians Rush knew—“bark and wine doctors” Rush considered no better than charlatans.[23] On one occasion, he compared Marsh to the deity Briareus of Greek mythology, a giant with one hundred arms and fifty heads:

Marcus has not, like Briarius, a hundred hands, but he can turn his two hands to a hundred different things.[24]

He prepared powders, treated patients with “blisters” (hot blankets soaked in vinegar and wrapped around the legs), and gave clysters (enemas), all according to Rush’s methods.[25] “I cannot tell you how much we all owe to Marcus,” the doctor wrote his wife:

Half the servants in the city have deserted their masters, and no wonder, for they were much exposed from the nature of their duty to taking the disorder, and when sick suffered and died from neglect.[26]

But Marcus Marsh remained to fight the epidemic alongside Rush. Marsh himself “yielded to the disease” in late September, but Rush reported that he was on the mend just four days later, and soon back at work.[27] When Rush fell ill in October, Marsh nursed him back to health. He slept in the doctor’s room, bringing him food, water, and medicine in the night—feeding him soup by hand as if Rush were “a child, or an old man.”[28] As the weakened physician recovered, Marsh visited Rush’s son and daughter in the countryside, examining them for signs of the illness and reporting back that both were in “good health.”[29] Little Benjamin Jr. was especially grateful: though shy in conversation, he told Marsh that “he loved him.”[30]


Present-day photo of Morven, the historic Stockton family residence and plantation farmed extensively by slave labor.

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At the end of October 1793, Benjamin Rush noted (no doubt with relief) that “the disease visibly and universally declines.”[31] By November the epidemic was over, cold weather having killed off the city’s mosquito population—though scientists would not identify mosquitos as the yellow fever vector until 1881, and the virus itself wouldn’t be isolated until 1927. In Philadelphia, Rush and others debated the origin of the disease and how best to prevent similar devastation in the future.[32]

Marcus Marsh, meanwhile, returned to the Rush home “to clean and whitewash the house and to purify all the infected articles of furniture in it,” in preparation for Julia and the children’s return.[33] His work had been invaluable, but in payment for his service, Marsh received only the suit of clothes Dr. Rush had worn during the fever.[34]

Five years later, 33-year-old Marcus Marsh sought a change of career. He applied for a Seamen’s Certificate for the Port of Philadelphia—inspired, perhaps, by the example of the sailor William Grubber. Marsh received his certificate with the help of Annis Boudinot Stockton; in 1798 she wrote a formal letter of manumission that officially documented Marsh’s legal status, and which he would need to carry on his person at all times to prove he was a free man.[35] Marsh was literate, and Annis—who corresponded regularly with George Washington and other prominent Americans—wrote to him as well, though no letters by Marsh survive.[36]

The details of his life after leaving the Rush household remain unknown. But as Benjamin Rush’s letters describe, without his skill and courage, the nation’s preeminent physician might have numbered among the 5,000 Philadelphians who perished during the 1793 epidemic.

About the AuthorPanel Toggle

R. Isabela Morales is an award-winning author and public historian. Her first book, Happy Dreams of Liberty: An American Family in Slavery and Freedom, received the 2023 Frederick Douglass Book Prize, the 2023 Tom Watson Brown Book Award, the 2023 Shapiro Book Prize, the 2023 William Nelson Cromwell Book Prize, the 2024 James F. Sulzby Book Award, and was a finalist for the prestigious Harriet Tubman Prize. Dr. Morales received her Ph.D. in history from Princeton University in 2019. She has been involved in the Princeton & Slavery Project since its founding as a researcher, contributing writer, editor, and project manager.

View all stories by R. Isabela Morales »

BibliographyPanel Toggle

A shorter version of this essay first appeared in the April 10, 2019 issue of the Princeton Alumni Weekly as "Benjamin Rush 1760: A Great Physician Had Help From a Freed Slave."

For a collection of primary sources related to Benjamin Rush's thoughts on race and slavery as well as the Yellow Fever epidemic of 1793, see The Benjamin Rush Portal Project, Penn Libraries.

ReferencesPanel Toggle


Janet A. Tighe, “Negotiating the Health of the Public: Yellow Fever in 1793 Philadelphia,” OAH Magazine of History 19, No. 5 (September 2005): 30-35; Jacquelyn C. Miller, “The Wages of Blackness: African American Workers and the Meanings of Race during Philadelphia’s 1793 Yellow Fever Epidemic,” The Pennsylvania Magazine of History and Biography 129, No. 2 (April 2005): 163-194.


Benjamin Rush to Julia Stockton Rush, letter dated 29 August 1793, Letters of Benjamin Rush, ed. L. H. Butterfield (Princeton, NJ: Princeton University Press, 1951), accessed 21 May 2019,


Benjamin Rush to Julia Stockton Rush, letter dated 29 August 1793.




Benjamin Rush to Julia Stockton Rush, letter dated 25 August 1793. See also Chris Holmes, “Benjamin Rush and the Yellow Fever,” Bulletin of the History of Medicine 40, No. 3 (May-June 1966): 246-263.


Benjamin Rush to Julia Stockton Rush, letter dated 25 August 1793.


Benjamin Rush to Julia Stockton Rush, letter dated 29 August 1793.


In 1790, more than 2,000 African Americans lived in Philadelphia (the vast majority free, with 301 enslaved). Miller, “The Wages of Blackness,” 169.


Benjamin Rush to Julia Stockton Rush, letter dated 21 September 1793.


Benjamin Rush to Julia Stockton Rush, letter dated 26 September 1793.


See Miller, “The Wages of Blackness"; Gary B. Nash, Forging Freedom: The Formation of Philadelphia's Black Community, 1720-1840 (Cambridge, MA: Harvard University Press, 1991).


Ibid., 177.


Martha J. King, “‘A Lady of New Jersey’: Annis Boudinot Stockton, Patriot and Poet in an Age of Revolution” in Women in the American Revolution: Gender, Politics, and the Domestic World (Charlottesville, VA: University of Virginia Press, 2019).


Annis Boudinot Stockton to Benjamin Rush, letter dated 3 November 1793, as quoted in ibid.


Benjamin Rush, An Address to the Inhabitants of the British Settlements in America, upon Slave-Keeping (Philadelphia: John Dunlap, 1773); Benjamin Rush, The Autobiography of Benjamin Rush, ed. George W. Corner (Princeton, NJ: Princeton University Press, 1948).


Stephen Fried, Rush: Revolution, Madness, and the Visionary Doctor Who Became a Founding Father (New York: Crown, 2018), 316.


Rush, The Autobiography of Benjamin Rush, 246; Fried, Rush, 290.


Fried, Rush, 316-317.


Ibid, 316-317, 346. Thanks to Stephen Fried for contacting the author about William Grubber's emancipation date. A previous version of this essay stated that he was not freed until 1794.


Rush, The Autobiography of Benjamin Rush, 246.


Benjamin Rush to Julia Stockton Rush, letter dated 15 October 1793.






Benjamin Rush to Julia Stockton Rush, letter dated 21 September 1793.




Benjamin Rush to Julia Stockton Rush, letter dated 15 October 1793.


Benjamin Rush to Julia Stockton Rush, letter dated 22 September 1793.


Benjamin Rush to Julia Stockton Rush, letters dated 15 October 1793 and 17 October 1793.


Benjamin Rush to Julia Stockton Rush, letter dated 20 October 1793.




Benjamin Rush to Julia Stockton Rush, letter dated 28 October 1793.


Rush subscribed to the (incorrect) theory that the disease had originated in Philadelphia itself rather than being carried into the city on infect ships, a position that put him at odds with city leaders, who feared that he would “destroy the character of Philadelphia for healthiness, and drive Congress from it.” Benjamin Rush to Julia Stockton Rush, letter dated 28 October 1793. See also Benjamin Rush, An Account of the Bilious Remitting Yellow Fever, as it Appeared in the City of Philadelphia, in the Year 1793 (Edinburgh: John Moir, Patterson’s Court, 1796), accessed 21 May 2019, Eighteenth Century Collections Online.


Benjamin Rush to Julia Stockton Rush, letters dated 28 October 1793 and 8 November 1793.


Wall text, Marcus Marsh, Morven Museum & Garden, Princeton, NJ.


“Record of Manumission of Marcus Marsh, 1798,” as quoted in Ibid.


Annis Boudinot Stockton to Benjamin Rush, letter dated 3 November 1793, as quoted in King, “‘A Lady of New Jersey’: Annis Boudinot Stockton, Patriot and Poet in an Age of Revolution.”

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