The Treaty of Alliance was the 1778 agreement that formally allied France with the United States during the Revolutionary War.
The treaty was signed in Paris on February 6, 1778, alongside the Treaty of Amity and Commerce. France had already been providing covert assistance to the American rebels, but the American victory at Saratoga helped convince the French government to recognize the United States and enter an open alliance.
Under the agreement, France promised military support and pledged not to make peace with Britain unless American independence was recognized. The alliance brought French troops, ships, weapons, money, and naval power into the conflict. French assistance became especially important during the Yorktown campaign, when a French fleet helped prevent British reinforcement or evacuation.
The Treaty of Alliance is different from the Treaty of Paris of 1783, which ended the war and secured British recognition of American independence. It is also distinct from the 1778 commerce treaty, which regulated trade and diplomatic relations. Together, the agreements marked a major international expansion of the American Revolution.