For the 1885 action in the Canadian North-West Rebellion, see the Battle of Fort PittThe Siege of Fort Pitt took place in 1763 in what is now the city of Pittsburgh, Pennsylvania, United States. The siege was a part of Pontiac's Rebellion, an effort by American Indians to drive the British out of the Ohio Country and back across the Appalachian Mountains. The Indian effort to capture Fort Pitt ultimately failed. This event is best known for the allegation of biological warfare.