Siege of Fort Detroit had apparently been informed of Pontiac's plan, and the garrison of about 120 men was armed and ready. Pontiac withdrew and, two days later, laid siege to the fort. A number of British soldiers and civilians in the area outside the fort were captured or killed; one of the soldiers was ritually cannibalized, as was the custom in some Great Lakes Indian cultures. The violence was directed only at the British: French colonists were left alone. Eventually more than 900 Indian warriors from a half-dozen tribes joined the siege. On May 28, a supply convoy commanded by Lieutenant Abraham Cuyler
Siege of Fort Pitt become by 1763 and how far British officers were willing to go in ignoring their own soldiers' code of warfare. A devastating smallpox epidemic plagued Native American tribes in the Ohio Valley and Great Lakes area through 1763 and 1764, but the effectiveness of these instances of efforts to spread smallpox remain unknown. After extensive review of surviving documentary evidence, historian Francis Jennings concluded the attempt at biological warfare was "unquestionably effective at Fort Pitt"; Barbara Mann deduced "it is important to note that the smallpox distribution worked"; Howard Peckham noted the resulting fatal epidemic "certainly affected their vigorous prosecution