The Siege of Yorktown became the final major land engagement of the American Revolutionary War in 1781.
American and French forces surrounded the British army commanded by Charles Cornwallis at Yorktown, Virginia. George Washington led the Continental Army, while French forces under the Comte de Rochambeau and French naval support under the Comte de Grasse helped make the siege decisive.
Cornwallis surrendered on October 19, 1781. The victory did not legally end the war immediately, and fighting continued in other places. However, Yorktown sharply reduced British willingness and political ability to continue major operations on the North American mainland.
The formal peace settlement came later. The Treaty of Paris was signed in 1783 and recognized the independence of the United States. Thus, 1781 is the key year for Yorktown, while 1783 is the year associated with the treaty that officially ended the war.