About a month and a half after Pontiac and his forces begin their attack on Fort Detroit, the uprising had spread to Fort Pitt. While considered a part of what is called Pontiac's rebellion, this war was a decentralized uprising of many Indigenous groups across Ohio Country and Allegheny Plateau areas. In the area of what would become Pittsburgh, Six Nations (Haudenosaunee), Lenape (Delaware), and Shawnee forces in the previous years had switched alliances during the Seven Years war to assist the British in taking Fort Pitt with the express promise that the British would vacate the area after defeating the French. Additionally, the British forces and settlers should have left the area due to it being on the westward side of the Proclamation Line. This and other general settler encroachments and disrespects had led to heightened tensions between the Indigenous groups and the settlers/British forces. The attack began on this day in 1763 and the siege lasted August 10th. It is notable for being one of the documented instances of biological warfare. At the time of the seige there was a current outbreak of smallpox within the fort, and on June 24th, a Lenape leader Turtleheart or Tahkoxitèh went in to negotiate and was given two blankets and a handkerchief from the smallpox hospital. American fur trader, merchant, and proponent of westward expansion William Trent's journal states "we gave them two Blankets and an Handkerchief out of the Small Pox Hospital. I hope it will have the desired effect." This was approved by Thomas Gage British Commander-in-Chief, North America. Further, Jeffery Amherst a month later in letter to Colonel Bouquet wrote "You will do well to try to inoculate the Indians by means of blankets, as well as to try every other method that can serve to extirpate this execrable race. I should be very glad your scheme for hunting them down by dogs could take effect, but England is at too great a distance to think of that at present." Eight towns across Canada and the US are still named after Amherst as well as a high school and a university. While Pontiac's uprising was successful in the fall of almost a dozen forts across Ohio country, the siege on Fort Pitt was ultimately unsuccessful. It remained under British control throughout Pontiac's war and stayed occupied after the Royal Proclamation which was supposed to (temporarily) stem westward expansion and settler encrouchment past the Continental Divide. It served an important role in settler expansion and land grabs during the era between the end of the Seven Years War and the American Revolution (fought in part to allow unregulated westward expansion by settlers into Native lands).