The point of land where the Monongahela and Allegheny Rivers meet to form the Ohio is a site of surpassing significance in the story of American expansion westward from the Appalachian Mountains. From the mid-18th century through the early years of the 19th, the Forks of the Ohio was a strategic key to the Ohio Valley and the vast territory drained by the upper Mississippi. Control of this point was a major objective in the struggle for North America, and men of three nations fought and died struggling for the forks. The bustling town of Pittsburgh arose sheltered by the series of fortifications on the point, the first permanent English settlement west of the Allegheny Mountains. This was a point of entry in the late 18th and early 19th centuries for the waves of settlement pushing into the Ohio and upper Mississippi Valleys, making it an early gateway to the West.
George Washington visited the forks in November 1753, during his mission to Fort Le Boeuf to sound out the intentions of the French and warn them away from the Ohio country. Washington strongly endorsed the forks as the best site to command the rivers. In February 1754 workmen of the Ohio Company under Capt. William Trent began building the first outpost at the forks. In April a force of French and Indians seized the hastily built stockade. They built Fort Duquesne, named in honor of the Governor General of New France. The rival French and British claims to the Ohio country, emphasized by the determination of each power to control the forks, precipitated the final pre-independence struggle, which spread abroad and became the Seven Years' War. - NPS