France and the United States signed the Treaty of Alliance on February 6, 1778.
The treaty created a defensive alliance during the American Revolutionary War. France agreed to support the American cause against Britain, while the United States promised not to make a separate peace. The agreement was signed in Paris by representatives of King Louis XVI and the Second Continental Congress.
French assistance had already reached the colonies secretly through arms, supplies, loans, and volunteers. The American victory at Saratoga in October 1777 helped persuade France that the rebellion had a realistic chance of succeeding. The treaty then made French military support official and open.
The Treaty of Alliance was signed alongside the Treaty of Amity and Commerce. These agreements are sometimes collectively called the Franco-American Alliance. France’s naval, military, and financial aid became especially important during the later campaigns, including the operations that culminated at Yorktown.