The Smallpox Crisis
Throughout the American Revolution, disease killed far more soldiers than combat — historians estimate that roughly two soldiers died of illness for every one killed in battle. Smallpox (Variola major) was the most feared of these diseases, capable of killing 20–30 percent of those it infected and leaving survivors disfigured or blinded. For an army drawing heavily on young men from rural communities with limited prior exposure to the disease, an uncontrolled outbreak could be catastrophic.
The disaster unfolded early. The American invasion of Canada in 1775–1776 — initially promising, capturing Montreal in November 1775 — collapsed in part because smallpox tore through troops besieging Quebec. By June 1776, approximately 5,000 of the 10,000 American soldiers sent to Canada were ill, the majority with smallpox. The retreat from Canada was less a military defeat than a medical evacuation. Meanwhile, British forces had long practiced systematic inoculation, giving them a significant asymmetric advantage: their troops were largely immune while American forces remained devastatingly vulnerable.
The disease also struck the freedom-seekers who had joined British forces. In mid-1776, Dunmore’s Ethiopian Regiment — enslaved Virginians who had escaped to join the British in exchange for freedom — suffered approximately 500 deaths from smallpox on Gwynn’s Island alone, reducing an effective fighting force of over 800 to roughly 150 men. (See: Dunmore’s Ethiopian Regiment.)
The Inoculation Procedure: Variolation
The technique available to Washington was variolation (also called inoculation), not the vaccine developed by Edward Jenner in 1796. The two procedures are distinct. In variolation, material taken from a smallpox pustule — either dried scab or fluid — was deliberately introduced into a healthy person’s skin, typically through a small incision. This produced a controlled case of smallpox: milder than natural infection in most cases, followed by lasting immunity.
The procedure carried real risk. In experienced hands, variolation killed roughly 1–2 percent of patients — dangerous, but far better than the 20–30 percent fatality rate of uncontrolled smallpox infection. Recovery took four to six weeks, during which patients were contagious and incapacitated. It was this recovery period that had led Washington to initially ban inoculation in May 1776: he feared that inoculating troops would render them useless for weeks precisely when British forces might strike.
Variolation had been practiced in the Ottoman Empire and parts of Asia for generations before reaching colonial America. In 1721, during a Boston smallpox epidemic, Puritan minister Cotton Mather — who had learned of the technique from his enslaved man Onesimus — persuaded physician Zabdiel Boylston to inoculate 287 Bostonians. Of those, six died (2 percent), compared to roughly 14 percent of uninoculated Bostonians who contracted the disease naturally. Despite this evidence, widespread fear and theological objections kept variolation controversial throughout the colonial period.
Washington’s Decision
As the catastrophic scale of disease losses became undeniable, Washington reconsidered. He had survived a smallpox infection himself as a teenager during a visit to Barbados in 1751 — the only time he left North America — and carried lifetime immunity. This personal experience gave him unusual perspective among American commanders.
On February 5, 1777, Washington issued orders for the mandatory inoculation of all incoming Continental Army recruits. He directed the program through Dr. William Shippen Jr., whom he appointed Director General of the Military Hospitals of the Continental Army. The logistics were carefully designed: new recruits would be inoculated immediately upon enlistment in Philadelphia — then the primary mustering point for soldiers from southern states — and would spend their recovery period being outfitted with uniforms and equipment. By the time they were fit to march, they would be immune and ready to join the main army in the field.
Washington deliberately conducted the program in secrecy. He wrote to Shippen: “Finding the Small pox to be spreading much and fearing that no precaution can prevent it from running thro’ the whole of our Army, I have determined that the Troops shall be inoculated.” He feared that publicizing the temporary weakness of partially inoculated troops would invite British attack during the vulnerable recovery period.
By March 1777, Washington extended the mandate: all recruits were to be inoculated in Philadelphia before joining the main army, and no soldier who had not been inoculated would be permitted to join the force in the field. This represented the first mass immunization policy in American history, implemented by executive military order rather than legislative action.
Implementation at Valley Forge and Beyond
The policy’s timing proved critical. Washington’s army spent the brutal winter of 1777–1778 encamped at Valley Forge, Pennsylvania — conditions famous for extreme hardship. Historians have noted that while disease ran rampant through the camp (typhus, dysentery, and pneumonia killed thousands), a devastating smallpox outbreak was largely averted because of the inoculation program already underway. The 2,500 soldiers who died at Valley Forge succumbed primarily to diseases other than smallpox — a stark contrast to what might have occurred without the immunization campaign.
Washington’s army at Valley Forge numbered approximately 11,000 men at its peak. That the force survived the winter as a coherent fighting force, despite losses, is partly attributable to the control of smallpox — though contemporary accounts focused more on the heroism of endurance than on medical logistics.
The program required significant medical infrastructure. Inoculation hospitals were established in Philadelphia and other locations, staffed by military surgeons working under Shippen’s direction. Managing thousands of temporarily incapacitated recruits — feeding, housing, and equipping them during a four-to-six-week recovery window — required coordination across the Continental Army’s stretched supply system.
Scientific and Medical Context
Washington’s decision placed him ahead of most of his contemporaries in applying medical evidence to policy. Opposition to variolation in America ran deep: religious objections held that deliberately inducing illness was an affront to Providence; practical concerns focused on the contagion risk; class anxieties noted that the well-to-do could afford private inoculation while the poor could not. Washington swept these objections aside in the name of military necessity.
The campaign also intersected with developments elsewhere in the Atlantic world. In Britain, variolation had become relatively standard medical practice for the wealthy by the 1760s. British military forces routinely inoculated, which contributed to their relative immunity advantage. French forces, allied with the Americans, were less consistent in their inoculation practices, suffering their own epidemic losses.
Washington’s inoculation mandate laid conceptual groundwork for institutional public health in America. Historian Elizabeth Fenn, in her 2001 study Pox Americana, argues that the smallpox epidemic of 1775–1782 was as significant a factor in the Revolution’s course as any military engagement — and that Washington’s response to it was one of his most consequential decisions. The policy foreshadowed later developments: the 1796 cowpox vaccine discovered by Edward Jenner, systematic military vaccination in the 19th century, and eventually the global eradication of smallpox in 1980.
Outcomes and Legacy
The inoculation program succeeded militarily. By 1778, smallpox had largely ceased to be an existential threat to the Continental Army, even as it continued to ravage civilian populations and, to some extent, British and Hessian forces. (See: Hessian Troops in the American Revolution.) Washington’s forces, while suffering from other diseases, typhus, and dysentery, were no longer losing entire campaigns to smallpox.
The policy’s legacy extends beyond the Revolution. It demonstrated that:
- A military commander could mandate medical intervention as a strategic necessity
- Large-scale immunization was logistically feasible under wartime conditions
- The benefits of controlled inoculation risk far outweighed the risks of epidemic spread
Washington’s decision remains one of the earliest examples of evidence-based public health policy in American history — a rational, pragmatic response to epidemiological reality that defied cultural opposition and proved decisive.
Sources
- History of Vaccines: Washington’s War Against Smallpox
- Army Heritage Center Foundation: Smallpox During the Revolutionary War
- American Battlefield Trust: Washington Inoculates an Army
- HISTORY: How Crude Smallpox Inoculations Helped George Washington Win the War
- National Geographic: How a smallpox epidemic nearly derailed the American Revolution
- Fenn, Elizabeth A. Pox Americana: The Great Smallpox Epidemic of 1775–82. Hill and Wang, 2001.