in september 1755, croghan fortified the post after general edward braddock's defeat at the battle of the monongahela. this was done in order to protect his stores and the 200 iroquois that had fled there after george washington's defeat at fort necessity. a few months later, the post was taken over by pennsylvania. the post became a small fort that would protect villagers against attacking natives, and would be a launching point for militia expeditions. shirley along with forts granville, lyttelton and patterson formed a defensive chain that stretched from the lower juniata river and aughwick creek valleys. croghan's fort was strengthened by provincial troops and officially named fort shirley early in 1756 by the british under hugh mercer.