 But were soon surrounded in a siege by a larger combined American-French army which had swiftly slipped away from guarding British occupied New York Town and marched quickly south laying siege to Cornwallis who was now trapped and isolated when the French Navy's West Indies fleet under Admiral de Grasse sailed north catching the British resupply and evacuation fleet, forcing its withdrawal in the offshore naval Battle of the Capes at the mouth of the Chesapeake Bay.A month later the beleaguered isolated Lord Cornwallis was forced to surrender to the superior allied Continental Army's General George Washington and French general comte de Rochambeau in October 1781.Two years later after further infrequent conflicts with dragged out treaty negotiations finally resulted in the Revolutionary War's end and British recognition of the new United States independence.