Fort Bosley

Fort Bosley was a fort fortified in 1777 in the Susquehanna Valley frontier to protect settlers. It was one of roughly a dozen frontier forts in the immediate Susquehanna Valley region. It was located near a grist mill built by John Bosley in 11773.

With the signing of the Treaty of Fort Stanwix (1768) between Great Britain and the Iroquois, permanent European settlement began to occur throughout much of present-day Pennsylvania, including the Susquehanna Valley. One of the first settlers near present-day Washingtonville was John Bosley who had moved to the area with slaves from Maryland.

Bosley built a grist mill along the eastern banks of Chillisquaque Creek near its convergence with Mud Run in 1773 (although the Commonwealth of Pennsylvania recognizes the Borough of Washingtonville’s settlement as 1775). With the large area of fine arable land along the Chillisquaque between the Muncy Hills to the north and Washingtonville Hill to the south, Bosley’s Mill became a necessity for settling farmers of the immediate area.

Despite authorized European settlement throughout the Susquehanna Valley, hostilities with natives of the area were commonplace. The magnitude of these tensions only intensified after the outbreak of the Revolutionary War. Following the defeat of General George Washington at the Battle of Brandywine, the decision was made to develop a system of forts along the Susquehanna Valley frontier to protect settlers and support the greater defense of Fort Augusta at present day Sunbury. Almost all of these frontier forts, roughly a dozen in the immediate Susquehanna Valley region, were developed either along the north or west branches of the Susquehanna River. Bosley’s Mill, which was fortified in 1777, was one of the few protected locations off of the two river branches.

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