It was June of 1775 and the British army was in control of Boston. George Washington had only recently become the commander of the colonial army and, while he had not fought at Bunker Hill, he arrived there shortly thereafter. He and his soldiers hid in the woodlands around the city watching and waiting for an opportunity to take Boston back. There were several problems with that plan, though. First, Washington did not have the weapons on hand for a siege. Second, even if the weapons had been available, they wouldn’t have done him much good since he didn’t have enough troops to actually lay siege. Yet both of these problems paled in comparison to the third. There was a smallpox outbreak in the city.
You can say what you like about Covid-19, but when you compare it to the great many diseases that have infected human beings throughout history, it is not as bad as most of them. I am not trying to make light of a pandemic that killed millions, but it is important to put it in perspective. Even at the very beginning, when there were no vaccines and no known treatments, Covid-19 rendered roughly 15 percent of those who caught it in North America and Europe seriously ill. Many of these sufferers ended up in the hospital. Some developed complications. Some of those with complications died. In short, for those who were identified as carrying Covid-19, the chance of dying from the disease in 2020 was around 1 to 3 percent. Now let’s take a look at smallpox.
Early stages of smallpox were not much different from Covid-19 and influenza. People would get a fever, they’d have aches and pains, they’d feel tired, and often develop nausea. Then the real horror of the virus emerged. Little pimples started to appear on the patient’s forehead.
These multiplied rapidly, covering the face and the inside of the mouth. They then spread pretty much everywhere else on the body. Over the next few days, these pimples filled with fluid. They transformed into the dreaded pustules (pox) that smallpox is known for. These were horrible round, hard, and raised structures that looked like Rice Krispies that had been inserted under the skin.
Patients were often covered with them from head to toe. The infectious liquid inside these pustules then slowly started leaking until, a couple weeks after the disease appeared, the pustules dried out, broke off the skin, and left behind permanent disfiguring scars. This was the “ordinary” version of smallpox, and conservative records indicate that it killed 30 percent of those who caught it. There were more deadly versions of the disease (aptly named the malignant and hemorrhagic variants). They killed just about everyone who caught them.
Washington knew smallpox well. The colonies had experienced some outbreaks, but they had not been as large or as frequent as those that had taken place back in England. This alone gave him pause, because while medical science at the time hadn’t developed the tools to tackle other serious diseases, it had made great strides against smallpox. So awful and devastating was the disease that extraordinary attention was being given to try and defeat it.
That attention started long before the war in the colonies. It did not start in Europe either. It was in China where the vile remains of the pustules from smallpox victims were being used as tools to help fight the disease. In some cases, the pustules were left to dry out for a few days after falling off of the body before being crushed into a fine powder and then blown through a pipe up a person’s nose. In other cases, the fluids from the pustules were collected and exposed to steam and a range of herbs before being placed onto cotton that was then stuck up a person’s nose.
Regardless of the method used, the person who had the smallpox essence put up their nose would catch a relatively mild form of the disease. Yes, they would be infectious, develop some pustules, and feel ill for a few days, but their chance of dying dropped from 30 percent to around 2 percent. More importantly, catching this mild form of the disease rendered the person immune to smallpox for life, just as if they had caught it normally. (A much safer vaccine was not invented until 1796.)
Some experts suggest that Taoist monks developed the technique as early as 1000 A.D., presenting the treatment as a form of magic.
The mild disease and immunity happened because the virus was not being transmitted in the usual manner of highly infectious respiratory droplets being coughed or sneezed from a very ill individual to the mouth or nose of a healthy person. More importantly, the smallpox virus particles were being intentionally damaged, by either the drying process or the steam and herb exposure process. These methods dramatically reduced the infectious load of viral material that a person was exposed to and gave their immune system a much better chance of getting the disease under control quickly. This is why fewer disfiguring pustules appeared, and why the fatality rate was much lower.
Precisely when these practices — collectively known today as inoculation — began and which ones were used first is difficult to determine because of greed. There are written records of Chinese alchemists having inoculated people during the 1500s, but they would not disclose their methods for fear of creating competition. After all, there was good money to be made, and being the only alchemist in town with the ability to stave off smallpox allowed such people to demand pretty much whatever price they wanted.
Some experts suggest that Taoist monks developed the technique as early as 1000 A.D., presented the treatment as a form of magic, and then passed the tradition along orally to other monks over the course of several centuries. There is a lot of debate about this and evidence is thin, but as an expert on the boundary between myth and science, I can certainly say that we have a long history of explaining things that we do not understand as the stuff of sorcery and then passing this along over centuries through stories, so the notion of a “magical inoculation recipe” being communicated with accuracy from generation to generation is certainly plausible.
The secrets of inoculation did not remain secret forever. Whether they made their way from China, India, or Northern Africa, the practice was known to be used in Turkey during the 1600s. By the time they got to Constantinople, the inoculation technique had changed somewhat. Cassem Algaida Aga, the ambassador from Tripoli to the Court of St. James, who had seen inoculation firsthand, reported, “If anyone hath a mind to have his children inoculated, he carries them to one that lies ill of the smallpox at the time when the pustules are come to full maturity. Then the surgeon makes an incision upon the back of the hand, between the thumb and the forefinger, and puts a little of the matter squeezed out of the largest and fullest pustules into the wound.”
Aga then went on to explain that “Out of a hundred persons inoculated not two die, whereas on the contrary, out of a hundred persons that are infected with the smallpox the natural way, there die commonly about thirty.”
Despite Aga’s letter, interest in inoculation remained low in England, but that was about to change. Lady Mary Wortley Montagu was the wife of Edward Wortley Montagu, the English ambassador to Constantinople in 1716. Her brother had died of smallpox just a couple of years earlier, and she herself had suffered a terrible bout of the disease that left her permanently disfigured.
She wrote many letters to her sister back in Britain, and one of them noted with astonishment that the women at the Turkish baths never had smallpox scarring on their skin. This led Montagu to question how the people of Turkey were avoiding the disease. She learned about inoculation and, desperate to keep smallpox from killing her son as it had her brother, she arranged for him to be treated against the disease.
After the boy responded well to the inoculation, Montagu tried to arrange for her younger daughter to be treated too, but was unsuccessful. When she came back to England in 1721, there was such a terrible smallpox outbreak that she decided to take the risk and have an English physician inoculate her daughter using the methods that she had learned about in Constantinople.
The procedure went well, so well that the physician used the same process to inoculate his own daughters. News of this technique spread quickly to the ear of Caroline, the Princess of Wales, who decided that the royal children ought to be protected against smallpox too. Soon, royalty all across Europe were being inoculated, including King Frederick II of Prussia, King Louis XVI of France, and Catherine II of Russia.
Those who were inoculated were often not told by the “experts” conducting the procedure that they should isolate themselves after being exposed to the virus. Sure, they might have had a weakened version of the disease, but they were still contagious, and could give a much stronger version of smallpox to those whom they came into contact with.
Just as Chinese alchemists tried to keep their inoculation methods secret to keep prices up, some English physicians tried to keep inoculation from becoming a procedure that just anybody could conduct. Arguing that bad blood needed to be removed before the inoculation could be successfully conducted, these physicians recklessly drained patients of their blood just before exposing them to smallpox. Far from helping in any way, these quacks sapped their patients of vital immune strength when they would need it most. It is not unreasonable to argue that their shameful methods actually increased fatality rates.
Amid the chaos and uncertainty created by British physicians miserably trying to commercialize inoculation, there were the politicians who were making matters even worse. While the Whig Party was, on the whole, supportive of smallpox inoculation, the Tory Party argued that inoculation was dangerous and best to be avoided.
It was against this complicated political and scientific environment in 1775 that George Washington weighed whether to try and retake Boston or delay his attack until the epidemic had passed. Reports from the time reveal that British deserters described that more than 2,000 soldiers in the city were ill with smallpox. They also reported to Washington that the British commander, General Howe, was making room in the city for reinforcements by forcing some of Boston’s residents to leave. Crucially, Howe was intentionally infecting these people just before they were displaced with, as one deserting British sailor reported, “the design of spreading the smallpox throughout the country and the [revolutionary] camp.”
This was, quite literally, germ warfare, and it forced George Washington to do what he did best: adapt. Rather than lay a traditional siege, he handpicked 1,000 men who reported that they had previously endured smallpox. Howe, with his diseased division in shambles, was forced to retreat and Washington’s 1,000 men, immune to the ravages of smallpox, secured Boston. This would not be the last time that smallpox would turn the tide of battle during the Revolutionary War.
George Washington’s understanding of smallpox, and his willingness to employ inoculation, paved the way for the 13 colonies to soon become the United States.
After Bunker Hill, Washington was convinced that a small regiment of British forces, along with residents in Canada, were likely to make an attack on Albany in upstate New York. To stave off this attack, 2,000 colonial soldiers and frontiersmen went up the St. Lawrence River. They got to Quebec and were successfully laying siege when smallpox reared its ugly head again. Nine hundred of the 2,000 colonials fell ill and were forced to retreat. In the end, nearly a third of them died from the disease.
Fear of smallpox, and a poor understanding of how much benefit could be granted by inoculation, led the Continental Congress to make a proclamation in 1776 banning the procedure. Washington knew this was a mistake. Indeed, he wrote to William Shippen, the director general of hospitals for the Continental Army, saying, “Should the disorder infect the Army in the natural way and rage with its usual virulence we should have more to dread from it than the Sword of the Enemy.”
With this in mind, he told the Continental Congress that its proclamation was wrong. Washington ordered mass inoculations of his troops and paired the procedure with strict follow-up quarantine measures to make sure that inoculated soldiers did not spread the full-strength disease to others.
The campaign worked. There were few fatalities and the Continental Army was soon composed of soldiers who were immune to the scourge of smallpox. It is not an overstatement to say that George Washington’s understanding of the disease, and his willingness to employ inoculation, paved the way for the 13 colonies to soon become the United States. It was also a pivotal moment for science.
Matt Kaplan is a science correspondent at The Economist whose work has appeared in National Geographic, New Scientist, Nature, and The New York Times. He is the author of “The Science of Monsters” and “Science of the Magical,” and is the co-author of David Attenborough’s “First Life: A Journey Through Time.”