What was the name of the 1778 pact that formalized the U.S. alliance with France?

The Treaty of Alliance formalized the military alliance between the United States and France in 1778.

The treaty was signed in Paris on February 6, 1778, by American commissioners Benjamin Franklin, Arthur Lee, and Silas Deane, along with French representative Conrad Alexandre Gérard. It followed the separate Treaty of Amity and Commerce, which established formal commercial relations and recognized American independence.

France had already provided covert aid, weapons, money, and supplies to the American cause. The American victory at Saratoga in October 1777 persuaded France that the rebellion had a realistic chance of succeeding. The treaty committed France to military cooperation if Britain attacked and barred either ally from making a separate peace with Britain.

French involvement became decisive during the later stages of the war. French troops and naval forces helped trap the British army at Yorktown in 1781. The treaty is sometimes called the Franco-American Treaty or part of the Franco-American Alliance, but its formal English title was the Treaty of Alliance.