<P> The Battle of the Chesapeake , also known as the Battle of the Virginia Capes or simply the Battle of the Capes , was a crucial naval battle in the American Revolutionary War that took place near the mouth of Chesapeake Bay on 5 September 1781 . The combatants were a British fleet led by Rear Admiral Sir Thomas Graves and a French fleet led by Rear Admiral Francois Joseph Paul , the Comte de Grasse . The battle was strategically decisive , in that it prevented the Royal Navy from reinforcing or evacuating the forces of Lieutenant General Lord Cornwallis at Yorktown , Virginia . The French were able to achieve control of the sea lanes against the British , allowing them to provide the Franco - American army with siege artillery and French reinforcements -- all of which proved decisive in the Siege of Yorktown , effectively securing independence for the Thirteen Colonies . </P>
who was responsible for keeping british ships out of the waterways off the coast of virginia
French