Final answer:
The Siege of Yorktown began on September 28, 1781, with American and French forces, led by General George Washington, laying siege to British forces commanded by Lieutenant General Lord William Cornwallis, which ultimately surrendered on October 19, 1781.
Step-by-step explanation:
The start of the Siege of Yorktown was on September 28, 1781. This significant military engagement was led by American commander General George Washington and French forces against British commander Lieutenant General Lord William Cornwallis. The Americans and the French combined their armies at Williamsburg, Virginia, marching to Yorktown to conduct a siege, effectively trapping the British forces on the peninsula. Despite plans for a breakout or relief from British forces, none succeeded, leading to Cornwallis's surrender on October 19, 1781. This decisive battle marked the last major action of the American Revolution and paved the way for American independence.