Final answer:
The siege of Yorktown was the conclusive battle of the American Revolution, where American and French forces besieged British General Cornwallis's troops, leading to their surrender and effectively ending the war.
Step-by-step explanation:
The siege of Yorktown in October 1781 was a pivotal moment in the American Revolutionary War. A combined force of American and French troops, numbering over 16,000, surrounded and laid siege to the British forces led by Lord Cornwallis in Yorktown, Virginia. The French fleet, under Admiral de Grasse, defeated the British fleet, gaining naval control and preventing Cornwallis's retreat by sea. After being trapped and unable to receive promised help from Lieutenant General Henry Clinton, Cornwallis's last hope failed when a breakout attempt across the York River was aborted. He surrendered his forces on October 19, 1781, effectively ending major hostilities in the war and paving the way to American independence.