<P> The Battle of Fort Duquesne was a British assault on the eponymous French fort (later the site of Pittsburgh) that was repulsed with heavy losses on 14 September 1758, during the French and Indian War . </P> <P> The attack on Fort Duquesne was part of a large - scale British expedition with 6,000 troops led by General John Forbes to drive the French out of the contested Ohio Country (the upper Ohio River Valley) and clear the way for an invasion of Canada . Forbes ordered Major James Grant of the 1st Highland Regiment to reconnoiter the area with 850 men . When Grant proceeded to attack the French position, his force was out maneuvered, surrounded, and largely destroyed by the French and their native allies led by François - Marie Le Marchand de Lignery . Major Grant was taken prisoner and the British survivors retreated fitfully to Fort Ligonier . </P> <P> After repulsing this advance party the French, deserted by some of their native allies and vastly outnumbered by the approaching Forbes, blew up their magazines and burnt Fort Duquesne . In November the French withdrew from the Ohio Valley and British colonists erected Fort Pitt on the site . </P> <P> Forbes commanded between 5,000 and 7,000 men, including a contingent of Virginians led by George Washington . Forbes, very ill, did not keep up with the advance of his army, but entrusted it to his second in command, Lt. Col. Henry Bouquet, a Swiss officer commanding a battalion of the Royal American Regiment . Bouquet sanctioned a reconnaissance of Fort Duquesne by Major James Grant of Ballindalloch, </P>

He british are defeated in the battle of ft. duquesne