When Smallpox Became a Weapon

Here is the simple truth: when most people think about war in the 1700s, they picture powdered wigs, lines of uniformed soldiers yelling orders, and smoke hanging in the air. Somehow, what people usually don't picture are viruses. However, smallpox? Smallpox was causing damage that even cannons couldn't contend with.

Before vaccines, smallpox was deadly. It was transmitted through close contact. What's most surprising is that it spread through objects, clothing, and blankets. Fever, painful blisters covering your body, and high death rates were all common results. Even if you survived, these scars would be etched into your life. Smallpox wasn't rare; it wasn't mild. It was one of the most terrifying diseases in the world. 

And now we increase the heat. Many Indigenous nations in North America had never been exposed to smallpox before Europeans arrived around the 1500s. No prior exposure meant no built-up immunity, so when this outbreak finally took place, it tore through communities. Disease reshaped the demographics and population of this continent in ways that battles could never.

Then came 1763. 

There was a major conflict known as Pontiac’s War, a coordinated resistance by Indigenous nations in the Great Lakes and Ohio Valley region against British control after Britain took over French territory. One of the key locations? Fort Pitt.

Fort Pitt was under siege by native forces. British soldiers and colonists. And inside the fort… was smallpox.

During the siege, a meeting was held under a flag of truce. British officers gave native representatives “gifts,” including two blankets and a handkerchief taken from the fort’s smallpox hospital. Not random blankets. Not fresh supplies. Blankets from the smallpox ward.

We know this because a trader and militia officer named William Trent wrote about it in his journal, stating he hoped it would have the “desired effect.” That isn't vague or accidental, that's intentional. 

And it doesn't stop here. Around the same time, British general Jeffrey Amherst was writing to Colonel Henry Bouquet. In their letters, they openly discussed the possibility of spreading smallpox among indigenous groups resisting British rule. Amherst suggested it. Bouquet replied that he would try to carry it out in a way that wouldn’t infect British troops.

So this wasn’t just a rumor or a legend that appeared years later. It’s documented in journals and military correspondence. People in positions of power recognized that disease could be weaponized and were willing to capitalise on it. 

Now, here’s where it gets complicated. Smallpox was already spreading in the region at the time. War creates chaos: movement of people, food shortages, and overcrowding. All of that helps the disease spread faster. Indigenous communities near Fort Pitt did experience outbreaks afterward, but historians can’t say with certainty how much of the damage was a direct result of these blankets. Epidemics don’t leave clean, easy-to-trace fingerprints.

What we can say for sure is that there was a deliberate attempt to use smallpox as a weapon in 1763. That alone makes it one of the clearest early examples of biological warfare in North American history.

It’s also important not to oversimplify. The significant loss of Indigenous individuals wasn’t caused solely by organized germ warfare campaigns. Most of it resulted from repeated waves of disease spreading unintentionally through colonization, trade, displacement, and violence. The Fort Pitt incident stands out because it crossed from passive spread into active intent.

And that’s what makes this episode so striking. It forces you to realize that people in the 1700s understood exactly what smallpox could do. They didn’t need microscopes to grasp its power. They saw its effects. And at least in this case, they tried to turn that power into a weapon.

So when you hear the phrase “smallpox blankets,” it’s not just dramatic storytelling. It refers to a specific, documented event during Pontiac’s War. It shows that biological warfare isn’t just a modern fear tied to laboratories and international treaties. It has deep, unsettling roots in colonial history.