During the early phase of the American Revolutionary War, the Continental Army struggled to supply food, clothing, weapons, pack horses, and lead for small arms ammunition, so Pennsylvania authorities turned to lead ore deposits in Sinking Valley. In the spring of 1778, an expedition from Carlisle under General Daniel Roberdeau was organized to mine local lead for the army, after the Pennsylvania Assembly approved him on March 30, 1778, to vest the lands and mine the lead. Named for Roberdeau and nicknamed for its mining purpose, Fort Roberdeau was built largely from April to June 1778 as a frontier fort for defense against Indian incursions and to help prevent evacuation of the frontier. On June 4, 1778, Roberdeau reported to General Washington that he had built at the mine in Sinking Springs Valley at the foot of Tussey Mountain a log fort, cabin fashion, fifty yards square with a bastion at each corner. Its horizontal log walls likely reflected ground too hard and rocky for a more common stockade wall, and the projecting bastions allowed a few men to survey and defend the area around the fort in several directions. The fort was never directly attacked and served as a safe haven for soldiers, lead miners, and local settlers.