Under imminent attack by Gen John Forbes, the French abandoned and burned Fort Duquesne. The fort was in the area named Pittsburgh in honor of William Pitt. The earliest known reference to the new name, Pittsburgh, is in a letter sent on this date from General John Forbes to William Pitt the Elder, 1st Earl of Chatham. This letter notified Pitt that his name had been given to the place, spelled “Pittsborough”.
Fort Mercer was then built by the British, as a temporary structure to replace Fort Duquesne, to defend the forks of the Ohio.