TURTLE CREEK, A RELICT PRE-GLACIAL VALLEY OF STRATEGIC IMPORTANCE TO PITTSBURGH DURING THE FRENCH AND INDIAN WAR

Turtle Creek is a major tributary of the Monongahela River approximately 13 km (8 miles) upstream of the confluence of the Monongahela and Allegheny Rivers. This confluence, known as the Forks of the Ohio (present-day Pittsburgh), comprised a strategic location in the French and English struggle for the dominance of the Ohio Valley region. During the French and Indian War (1754-1763), two major British expeditions were organized for the purpose of capturing the French Fort Duquesne at the Forks of the Ohio: the Braddock Campaign in 1755 and the Forbes Campaign of 1758. The French, themselves, destroyed Fort Duquesne in November of 1758 during the approach of General Forbes’ army. The above campaigns as well as future expeditions originated from the east and involved several thousand troops, supply wagons, and herds of livestock. Road building was a major effort that occurred during the progress of the expeditions, and roads had to either cross, traverse, or avoid Turtle Creek Valley before approaching the Forks. The topography of Turtle Creek Valley is the product of a pre-Illinoisan drainage system that carried much of the water from the Appalachian Plateau north to the pre-glacial St. Lawrence Valley. The relict Turtle Creek Valley is larger and wider than surrounding contemporary valleys and presents either a large steep valley to cross or a gently-sloping access to the Monongahela River and Fort Duquesne when traversed. The latter is in sharp contrast to the steep, rugged topography of the dissected uplands surrounding present-day Pittsburgh. Turtle Creek Valley also contained several, narrow gorge-like areas where conditions were ideal for ambush-style warfare. The British were aware of these locations and the 1755 Braddock expedition crossed the Monongahela River purposely avoiding the valley for these reasons.