Battle of Fort Duquesne 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 . 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 outmanouevred , 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 . 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 . British forces . Forbes commanded between 6 , 000 and 8 , 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 , acting commander of the 77th Regiment of Foot ( Montgomerie ' s Highlanders ) . hi Battle . On September 11 , 1758 , Grant led over 800 men to scout the environs of Fort Duquesne ahead of Forbes ' main column . Bouquet believed the fort to be held by 500 French and 300 Indians , a force too strong to be attacked by Grant ' s detachment . Grant , who arrived in the vicinity of the fort on September 13 , believed there were only 200 enemy within , and sent a small party of 50 men forward to scout . These saw no enemy outside the fort ; they burned a storehouse and returned to Grant ' s main position , two miles ( 3 km ) from the fort . The next morning , Grant divided his force into several parts . A company of the 77th , under a Capt . McDonald , approached the fort with drums beating and pipes playing as a decoy . A force of 400 men lay in wait to ambush the enemy when they went out to attack McDonald , and several hundred more under the Virginian Maj . Andrew Lewis were concealed near the force ' s baggage train in the hope of surprising an enemy attack there . The French and Indian force was in fact much larger than anticipated , and moved swiftly . They overwhelmed McDonald ' s decoy force and overran the party that had been meant to ambush them . Lewis ' s force left its ambush positions and went to the aid of the rest of the force but the French and Indians had by then gained a point of high ground above them and forced them to retire . The Indians used the forest to their advantage ; " concealed by a thick foliage , their heavy and destructive fire could not be returned with any effect " . In the one - sided battle in the woods , the British and American force suffered 342 casualties , of whom 232 were from the 77th Regiment , including Grant , who was taken prisoner . Out of the eight officers in Andrew Lewis ’ s Virginian contingent , 5 were killed , 1 was wounded and Lewis himself was captured . Nevertheless , most of Grant ' s force escaped to rejoin the main army under Forbes and Bouquet . The Franco - Indian force suffered only 8 killed and 8 wounded . A plaque on the Allegheny County Courthouse , erected in 1901 commemorates the site of the battle , and the hill where the battle was fought is today called Grant Street , in Pittsburgh . French retreat . Though the French had beaten off the initial British attack , Lignery understood that his force of about 600 could not hold Fort Duquesne against the main British force of more than ten times that number . The French continued to occupy Fort Duquesne until November 26 , when the garrison set fire to the fort and left under the cover of darkness . As the British marched up to the smoldering remains , they were confronted with an appalling sight . The Indians had decapitated many of the dead Highlanders and impaled their heads on the sharp stakes on top of the fort walls , with their kilts displayed below . The British and Americans rebuilt Fort Duquesne , naming it Fort Pitt after the British prime minister William Pitt , who had ordered the capture of that strategic location .