Rebellion against the Europeans and civil war further destabilized the Americas making them ideal for European conquest.
Recognizing the deadly power of the virus, Sir Jeffrey Amherst, the commander-in-chief of the British forces in North America during the French-Indian war (1754 - 1763), suggested the idea of using smallpox as biological warfare. In the 19th century, historian Francis Parkman came across correspondence in which Amherst discussed its use with Col. Henry Bouquet, an officer positioned at the western frontier. The speculation is that Amherst and his army gave smallpox infected blankets to their Native American foes in an attempt to infect them. However, it was never confirmed whether or not such a biological attack ever occurred.
Realizing how easily the smallpox virus could spread, methods were developed to control the outbreaks. One of the first methods, dating back to 6th century China was the use of variolation. Variolation was the process by which matter from smallpox sores was purposely transferred to people who had never been infected.
The goal was to deliberately infect individuals with a small dose of the virus in the hopes of inducing a mild form of the infection to which they could mount antibodies and develop immunity.
In contrast to the Asian and African method of inoculation (blowing dried smallpox scabs up the nose), the procedure most commonly carried out in Europe and America involved rubbing the smallpox matter into superficial skin scratches. With variolation, patients usually went on to develop smallpox-like symptoms; however, much fewer people died from variolation (1-2%) than if they had naturally acquired smallpox (30%).
Despite variolation, smallpox continued to wreak havoc among the rich and the poor alike. In the 17th and 18th centuries, it killed several European monarchs including Queen Mary II of England, Czar Peter II of Russia, and King Louis XV of France. Queen Elizabeth I of England and American President Abraham Lincoln also both came down with smallpox during their times in office, though they survived. By the end of the eighteenth century, the disease accounted for nearly 400,000 deaths per year, worldwide.