Nation & World
Did the British unleash biological warfare against Washington’s troops?

Historians trace role of physicians, medicine, disease during war in articles marking 250th anniversary of Declaration of Independence

Sy Boles

Harvard Staff Writer

March 17, 2026 5 min read

“In the Revolution, physicians were relatively more prominent than they have been in subsequent moments of American history,” said David S. Jones.

Veasey Conway/Harvard Staff Photographer

In addition to coverage of related events and exhibits, the Gazette will publish a series of occasional features marking the 250th anniversary of the Declaration of Independence. This is the first.

George Washington had a problem in the winter of 1777.

Smallpox was devastating the already undermanned Continental Army, and much-needed new recruits were being quarantined for a month as a precautionary measure. In addition, Washington had intelligence that the British had devised a scheme to infect more troops.

So the general made a fateful decision. Every soldier and recruit would be inoculated, a technique by which they would be infected, likely get a mild case, and acquire immunity.

Washington wrote to military physician William Shippen Jr.: “If the business is immediately begun and favoured with the common success, I would fain hope they will be soon fit for duty, and that in a short space of time we shall have an Army not subject to this the greatest of all calamities.”

This case of potential Colonial biological warfare was recently recounted in the New England Journal of Medicine as part of a series looking at the role of physicians, medicine, and disease in the American Revolution to mark the 250th anniversary of the signing of the Declaration of Independence.

“In the Revolution, physicians were relatively more prominent than they have been in subsequent moments of American history,” said David S. Jones, one of the authors of the article as well as the A. Bernard Ackerman Professor of the Culture of Medicine at Harvard Medical School and a professor of epidemiology at the Harvard T.H. Chan School of Public Health.

“In these battles, as in most wars, more soldiers were dying of disease than were dying of combat,” he said.

“Colonial warfare was just a violent, awful thing. Is spreading smallpox any more violent or awful? It bugs us. I don’t think it bugged them at the time.”

Jones will be joined in the project by a team of fellow medical historians from Harvard and elsewhere. The list of potential subjects is not short.

Benjamin Rush, a physician and one of the signers of the Constitution, was a prolific and influential writer opposed to slavery and in favor of free public schools and prison reforms. John Warren, a Roxbury native and a Continental Army physician, went on to found Harvard Medical School; his son, John Collins Warren, founded the NEJM and served as Harvard Medical School’s first dean.

The parts of the stories that intrigue Jones most are the ones where open questions — or outright mysteries — remain.

Take Washington’s inoculation decision.

In December 1775, months before his decision to inoculate the entire army, Washington had Boston surrounded. Some 6,000 British soldiers and about 6,000 civilians had been trapped since spring, and smallpox and dysentery were rife in the besieged city.

The general received word that some refugees fleeing the city had been found to have smallpox. It fueled his suspicion — which was never conclusively proved — that the British were seeking ways to spreading the disease as an act of war.

“The patriots were convinced it was happening,” Jones said.

And it wouldn’t have been out of character, he said. Some of the British personnel trapped in Boston were among those who purposely gave blankets and other items from a smallpox infirmary to Native American diplomats in 1763 during an armed conflict.

“But no one has ever found a smoking gun [in the Boston siege]. No one has found a letter from [British Major General] Thomas Gage to someone in the British high command saying, ‘Let’s do this,’” Jones said.

And he has looked. Almost everything related to the American side of the Revolution has been digitized by the U.S. National Archives, but British materials are less readily available online. So he spent some time in U.K. archives searching for anything previous historians might have missed. No such luck.

Would it make a difference if there were hard proof? Not necessarily for the Continental Army at the time, who were convinced the biological warfare was happening and acted accordingly, setting up smallpox hospitals to contain the spread of the disease and even dipping letters in vinegar to disinfect them before they were read.

And knowing for sure wouldn’t necessarily change our understanding of Colonial-era warfare, Jones said.

Historians already know that both sides readily engaged in what we would now consider war crimes, from destroying the enemy’s crops to killing prisoners of war.

“Colonial warfare was just a violent, awful thing,” Jones said. “Is spreading smallpox any more violent or awful? It bugs us. I don’t think it bugged them at the time.”

Finding the proof would matter, Jones said, to thoroughly tell the truth about America’s founding war and medicine’s role in winning it.

“Battlefield conditions do a lot to advance the cause of surgery, but the most important contributions of physicians to wars have usually been how to keep soldiers healthy so they’re able to fight,” he said. That includes managing disease and hygiene, digging latrines, and providing and protecting safe and sanitary food and drinking water.

Jones is being joined in the project by collaborators Scott Podolsky, professor of global health and social medicine at Harvard Medical School; Jeremy Cannon, M.D. ’98, professor of surgery at the University of Pennsylvania’s Perelman School of Medicine; and Justin Barr, transplant surgeon at New Orleans’ Ochsner Medical Center.

The group plans to publish as many as eight pieces through September 2033, the 250th anniversary of the end of the Revolution.