The fort was built from 1759 to 1761 during the French and Indian War, next to the site of former Fort Duquesne, at the confluence the Allegheny River and the Monongahela River. The French built Fort Duquesne in 1754, at the beginning of that war, and it became a focal point due to its strategic river location. The Braddock expedition, a 1755 attempt to take Fort Duquesne, met with defeat at the Battle of the Monongahela at present-day Braddock, PA. The French garrison defeated an attacking British regiment in September 1758 at the Battle of Fort Duquesne. They abandoned and destroyed the fort at the approach of General John Forbes's expedition in November.
The Forbes expedition was successful where the Braddock expedition had failed because the Treaty of Easton of 1758 reduced French alliances with Native American tribes. Chiefs of 13 American Indian nations agreed to negotiate peace with the colonial governments of Pennsylvania and New Jersey and to abandon any alliances with the French. The nations were primarily those of the Iroquois, Lanape (Delaware), and Shawnee, who agreed to the treaty in return for the British governments' promising to respect their rights to hunting and territory in the Ohio country, to prohibit establishing new settlements west of the Appalachian Mountains, and to withdraw British and colonial military troops after the war. The Indians wanted a trading post at Fort Duquesne, but they did not want a British army garrison or colonial settlement. The colonists built a new fort and named it Fort Pitt, after William Pitt the Elder.
After the war and in the face of continued colonial encroachment, in 1763 the western Delaware and Shawnee took part in Pontiac’s Rebellion, an effort to drive the settlers out of the region. The Indians' siege of Fort Pitt began on June 22, 1763, but they found it too well-fortified to be taken by force. In negotiations during the siege, Captain Simeon Ecuyer, the commander of Fort Pitt, gave two Delaware emissaries blankets that had been exposed to smallpox, in hopes of infecting the surrounding Indians and ending the siege. The attempt was probably unsuccessful. On August 1, 1763, most of the Indians broke off the siege to intercept an approaching force under Colonel Henry Bouquet. In the Battle of Bushy, Bouquet fought off the Indian attack and was able to relieve Fort Pitt on August 20.
After Pontiac's War, the British Crown no longer needed Fort Pitt. They turned it over to the colonists in 1772. At that time, the Pittsburgh area was claimed by the colonies of both Virginia and Pennsylvania, which struggled for power over the region. After Virginians took control of Fort Pitt, they called it Fort Dunmore, in honour of Virginia's Governor Lord Dunmore. The fort served as a staging ground in Dunmore’s War of 1774. Notice was given to area residents of an auction of all salvagable remains of the fort on August 3, 1797 after the U.S. Army decommissioned the site.
Photos supplied by Contemporary Makers' European Correspondent, Manfred Schmitz.
Copy from Wikipedia.