Louis XVI allied France with the United States after the American victory at Saratoga.
Louis XVI was king of France from 1774 until 1792. His government had already provided the American Patriots with covert supplies and financial assistance, but the Saratoga victory in October 1777 convinced France that the rebellion had a realistic chance of defeating Britain.
France and the United States signed the Treaty of Amity and Commerce and the Treaty of Alliance on February 6, 1778. The agreements recognized the United States as a trading partner and committed France to support the American war effort. French involvement expanded the conflict into a global war.
French troops, money, weapons, and naval power became crucial to the American cause. French naval operations helped prevent British relief at Yorktown in 1781, where General Cornwallis surrendered. Louis XVI's support for the American Revolution also worsened France's financial problems, which contributed to the crisis preceding the French Revolution.