France’s navy helped trap Cornwallis at Yorktown, a decisive 1781 event remembered by America250.
The key naval action was the Battle of the Chesapeake, also called the Battle of the Capes, fought on September 5, 1781. The French fleet under Admiral François Joseph Paul de Grasse prevented the British fleet from gaining control of Chesapeake Bay.
That result isolated the British army under General Charles Cornwallis at Yorktown. Without reliable naval support or an open route for evacuation, Cornwallis faced the combined American and French armies commanded by George Washington and the Comte de Rochambeau. The siege ended with Cornwallis’s surrender on October 19.
France had formally entered the war against Britain in 1778, after the American victory at Saratoga helped secure the Franco-American alliance. French military, naval, financial, and logistical assistance was crucial, although the United States remained responsible for its own political independence.