Which 1781 naval battle stopped the British from relieving Cornwallis at Yorktown?

The Battle of the Chesapeake stopped the British from relieving Cornwallis at Yorktown in 1781.

Also called the Battle of the Capes, the engagement took place on September 5, 1781, near the entrance to Chesapeake Bay. A French fleet commanded by the Comte de Grasse fought a British fleet led by Rear Admiral Sir Thomas Graves. The battle was tactically indecisive, but the British fleet withdrew from the bay.

That withdrawal had major consequences. French control of the Chesapeake prevented the Royal Navy from supplying or evacuating Cornwallis’s army at Yorktown. De Grasse’s ships also supported the allied siege by helping maintain the blockade and transporting resources.

The American and French land forces completed the encirclement of Yorktown, leading to Cornwallis’s surrender on October 19, 1781. The naval battle is sometimes overshadowed by the land siege, but Washington later regarded control of the Chesapeake as essential to the victory.