Fort Duquesne, c. 1754.I thought Fort Fayette was near or at the site of the French Fort Duquesne and British Fort Pitt (from which Pittsburgh takes its name). Both forts were built on the point of land where the Allegheny and the Monongahela rivers join to form the Ohio. Actually, it turned out to be located on the Allegheny River a mile or so upstream from the point. Although massive, the British fort was flooded and damaged several times, and the American government sold the land and moved the military post to the upstream site.
An early American map of Pittsburgh. The ruins of Fort Pitt still stood at the confluence of the rivers but Fort Fayette was the active military base (note the overland route to Philadelphia, which was originally the military road cut by General Forbes' Expedition during the French and Indian War).
Fort Duquesne was a threat to British settlements in the western Pennsylvania and Virginia region that had to be wiped out. They sent a big expedition under General Braddock in 1755, consisting of two Regiments of Foot, the 44th and 48th, recently arrived from Ireland. Several hundred Provincial militia, including the young Colonel Washington, also accompanied the force.
It did not go well.
Here you can see some of the remains of the expedition.
Braddock's men debarked in Alexandria, Virginia (a couple miles outside of modern Washington, D.C.) and blazed a road overland nearly to the forks of the Ohio. They dragged cannon with them to use against the French outpost.
The outnumbered French had sent a force to harass the column, but it unexpectedly ran into a British vanguard before a ambush could be set.
The British foot regiments had flankers but they were not equipped or trained to fight in the woods. The disorganized column tried to repulse the French with platoon volleys but had no room to rally and reorganize itself. After taking considerable casualties a rout ensued.
General Braddock was killed, and his volunteer Aide-de-Camp, Colonel Washington, took command and led the troops back a ways.
Although this remnant of a cannon was not labeled, I assume it was dug up near the other relics. The British Colonel who eventually took over command of the survivors ordered the artillery to be buried and the wagons burned before retreating. This cannon has had its trunnions knocked off, a common way to disable artillery.
Braddock himself was buried anonymously in the road named after him. Remains believed to be his were dug up in 1908 and interred in a proper tomb but who knows?