The allied nation that provided crucial naval support during the Battle of Yorktown was France.

France was the allied nation that offered vital naval support during the Battle of Yorktown. The French navy was instrumental in the 1781 siege by preventing British reinforcements and supplies from reaching the area, effectively trapping General Cornwallis's troops on land. This strategic blockade enabled American and French forces, led by General George Washington, to coordinate their attack successfully. The partnership between the two nations highlighted the importance of international alliances in the American Revolutionary War. Ultimately, the French naval support was crucial in securing Cornwallis's surrender, playing a significant role in the pursuit of American independence and influencing the nation's future.