They call it the Fort that Saved America. It is the winter of 1777. The Revolutionary War has raged for more than two years. In Pennsylvania, the British troops are in dire need of resupply. Those supplies sit in the hold of Royal Navy ships, which stand ready to sail up the Delaware River and deliver them to the hungry redcoats. Just one thing stands in their way: Fort Mifflin. Garrisoned by a die-hard band of ragged Colonials,...