Pontiac (Ottawa leader) On May 9, he laid siege to the fort, and was eventually joined by more than 900 warriors from a half-dozen tribes. While Pontiac was besieging Fort Detroit, messengers spread word of his actions. Indians made widespread attacks against British forts and Anglo-American (but not French) settlements, and at one point controlled nine of eleven British forts in the Ohio Valley. They destroyed Fort Sandusky. In July 1763, Pontiac defeated a British detachment at the Battle of Bloody Run, but he was unable to capture the fort. In October, he lifted the siege and withdrew to the Illinois Country, where
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