Fort Loudoun (or Fort Loudon, after the modern spelling of the town) was a fort in colonial Pennsylvania, one of several forts in colonial America named after John Campbell, 4th Earl of Loudoun. The fort was built in 1756 during the French and Indian War by the Second Battalion of the Pennsylvania Regiment under Colonel John Armstrong, and served as a post on the Forbes Road during the Forbes expedition that successfully drove the French away from Fort Duquesne. A replica of the fort was built on the original site in 1993.