The Treaty of Alliance formally created a military alliance between the United States and France when it was signed in Paris on February 6, 1778. It was negotiated during the American Revolutionary War.
The treaty promised French military support if Britain attacked France because of the conflict and established conditions for cooperation against Britain. It was signed alongside the Treaty of Amity and Commerce, which recognized American independence and established commercial relations. The two agreements are often discussed together as the Franco-American Alliance.
France's entry transformed the war into a wider international conflict. French supplies, troops, naval forces, and financial assistance became important to the American war effort, especially during the Yorktown campaign. The military alliance was later strained by events in revolutionary France and formally ended in 1800 through the Treaty of Mortefontaine.