English: Washington's March & Naval Actions Map August-September 1781: Fall of 1781 presented Continental Army General George Washington with an important opportunity - that of trapping and defeating British General Lord Cornwallis at a small Virginia port town named Yorktown. Cornwallis had been ordered to take a post with his army and await the arrival of a Royal Navy fleet to extract him. Washington learned of this and left a "ghost army" outside New York to fool the British there while moving the bulk of his army south into Virginia. After taking precautions to prevent his leaving by land the entrapment of Cornwallis was complete when the Royal Navy fleet sent for him was defeated by a French fleet off the Virginia Capes. NOTE: Click on the map once to obtain a larger image. (Online Atlas Collection, History Department, U.S. Military Academy at West Point).(this illustration incorrectly asserts that Admiral Graves returned to New York on September 4th.)