Whose error made the victory at Yorktown possible?

Answer 1

In June 1781, British general Lord Cornwallis instead attacking the inferior American Army of 4,500 men, led by the Marquis of Lafayette, the Baron von Steuben and gen. John Wayne, with his overwhelming force of 7,500 men, chose to retreat eastward to the coast to maintain sea communication with Sir Henry Clinton in New York City.

As the British Fleet had been driven off the Bay of Chesapeake by De Grasse's French Fleet, he could not relieved and evacuated and remained trapped in Yorktown between Washington's and Rochambeau's Army coming from the north and Lafayette's Army of Virginia.