The Americans won the Battle of Yorktown because the British were low on reinforcements and got the assistance of the French. The Battle of Yorktown was an important and historic battle because it was the last battle of the American Revolution. The British had won a series of victories against the Americans in past battles.
After the Battle of Guildford Court, British General Charles Cornwallis moved his army to the coast of North Carolina. He was ordered to stay in the Carolinas to support the British army, but he chose not to remain. Instead, Cornwallis moved his troops to Yorktown, Va. Because the British army had just fought the Battle of Guildford Court, they were low on reinforcements and were waiting for more from New York. At the same time, the American army was planning to attack the British army in New York with the help of the French army.
The British were aware that the American army was planning to attack New York, so they failed to send reinforcements to Yorktown. General Cornwallis was ordered to bring his troops to New York, but again he declined. The Americans won the battle, and on October 6, 1781, the Americans and the French attacked the British army in Yorktown, forcing them to surrender.