How the French Navy helped win America's Independence

The naval force that played the most important role in achieving American independence was not American at all--it was French.
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As the British established themselves at Yorktown, Washington and his army of 9,000 camped around New York City. Seeking an opportunity to cut off Cornwallis's contact with the Royal Navy, Washington urgently requested the support of the French fleet then operating in the Caribbean. Washington's plan called for a combined naval and land offensive against Cornwallis. Rear Admiral J. P. Compte de Grasse responded to Washington's call by sailing his French battle fleet of twenty-eight ships north toward Virginia. Simultaneously, on August 21, 1781, Washington began moving his army south.

Leaving 2,500 troops with Major General Heath in New York to screen the withdrawal of the remainder of the American army, Washington began the long trek south through New Jersey and Philadelphia to the northern end of the Chesapeake Bay.