The gristmill was built in about 1773 by John Bosley, who moved to the area from Maryland a few years before the American Revolution. For the early settlers of this region, hostilities with the Native Americans of the area were commonplace, which 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 in the Susquehanna River Valley to protect settlers and support the defense of Fort Augusta. About a dozen forts were then established along the branches of the Susquehanna River, one of which was Bosley’s Mill, which was fortified and stockaded in 1777.
It became a haven of refuge for area families while their husbands and fathers were fighting in the war. It was soon recognized by the military authorities as a post of importance and was garrisoned by troops. After the fall of Fort Freeland in July 1779, the fort became even more important, holding the forks of the Chillisquaqua River and defending the stream below it. During its tenure, there are no records of any attacks.
John Bosley sold his mill and surrounding land in 1795. It burned down in 1826 and no evidence of the mill exists today. A historic marker along Route 54 in Washingtonville, Pennsylvania.
Compiled by Kathy Weiser-Alexander, updated February 2020.