During the summer of 1781, the armies of Generals Washington and Rochambeau were encamped in lower Westchester County at Dobbs Ferry, Ardsley, Hartsdale, Edgemont and White Plains. It was a time of military deadlock and grim prospects for the allied Americans and French. Washington recognized that a decisive victory was needed or America would never achieve independence. In August, he marched these soldiers to Virginia to face General Cornwallis and his redcoats. Washington risked all on this march. Its success required secrecy, and he prepared an elaborate deception to convince the British...