Comte de Grasse commanded the French fleet that helped trap the British at the 1781 Siege of Yorktown. His naval forces prevented British relief ships from breaking the Franco-American blockade.
De Grasse sailed from the Caribbean to the Chesapeake Bay with a large French fleet. The resulting Battle of the Chesapeake on September 5, 1781, ended without a decisive tactical victory, but the British fleet withdrew. That withdrawal left General Charles Cornwallis isolated at Yorktown.
George Washington’s Continental Army and French troops under Comte de Rochambeau then completed the land siege. Cornwallis surrendered on October 19, 1781. De Grasse’s role is sometimes confused with Rochambeau’s: Rochambeau commanded French land forces, while de Grasse commanded the naval force essential to controlling the Chesapeake.