Washington was not mistaken.  The work was indeed done.  Tarleton early in the siege had dashed out against Lauzun on the other side of the river and been repulsed.  Cornwallis had been forced back steadily into the town, and his redoubts, as soon as taken, were included in the second parallel.  A sortie to retake the redoubts failed, and a wild attempt to transport the army across the river was stopped by a gale of wind.  On the 17th Cornwallis was compelled to face much bloody and useless slaughter, or to surrender.  He chose the latter course, and after opening negotiations and trying in vain to obtain delay, finally signed the capitulation and gave up the town.  The next day the troops marched out and laid down their arms.  Over 7000 British and Hessian troops surrendered.  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.  It is difficult to manage allied troops.  It is still more difficult to manage allied troops and an allied fleet.  Washington did both with infinite address, and won.  The chief factor of his success in this direction lay in his profound personal influence on all men with whom he came in contact.  His courtesy and tact were perfect, but he made no concessions, and never stooped.  The proudest French noble who came here shrank from disagreement with the American general, and yet not one of them had anything but admiration and respect to express when they wrote of Washington in their memoirs, diaries, and letters.  He impressed them one and all with a sense of power and greatness which could not be disregarded.  Many times he failed to get the French fleet in cooeperation, but finally it came.  Then he put forth all his influence and all his address, and thus he got De Barras to the Chesapeake, and kept De Grasse at Yorktown.