The event that marked the culmination of the American Revolutionary War was the Siege of Yorktown in 1781. This decisive battle occurred when British General Cornwallis and his troops were surrounded by American and French forces, leading to his surrender on October 19, 1781. The successful siege effectively ended major military operations in the colonies and prompted peace negotiations. The victory at Yorktown significantly boosted American morale and patience for independence and later led to the Treaty of Paris in 1783, officially recognizing the United States' sovereignty and independence from Great Britain.