It was a crushing defeat.

The victorious army consisted in round numbers of 5500 continentals, 3500 militia, and 7000 French, and they were backed by the French fleet with entire control of the sea.
When Washington had once reached Yorktown with his fleet and army, the campaign was really at an end, for he held Cornwallis in an iron grip from which there was no escape.

The masterly part of the Yorktown campaign lay in the manner in which it was brought about, in the management of so many elements, and in the rapidity of movement which carried an army without any proper supplies or means of transportation from New York to the mouth of Chesapeake Bay.

The control of the sea had been the great advantage of the British from the beginning, and had enabled them to achieve all that they ever gained.

With these odds against him, with no possibility of obtaining a fleet of his own, Washington saw that his only chance of bringing the war to a quick and successful issue was by means of the French.