France and the United States signed their Treaty of Alliance in 1778.
The treaty was signed in Paris on February 6, 1778, after the American victory at Saratoga helped convince France that the rebellion had a realistic chance of success. Benjamin Franklin, Arthur Lee, and Silas Deane signed for the United States, while Conrad Alexandre Gérard represented France.
A related Treaty of Amity and Commerce recognized the United States and established commercial relations. The Treaty of Alliance created military obligations if Britain attacked France because of the new connection. France soon provided weapons, money, troops, and naval support.
French participation became crucial at Yorktown in 1781, where French soldiers and warships helped trap Cornwallis’s army. The alliance also internationalized the conflict: Britain declared war on France in March 1778, and Spain later joined France against Britain. The wartime relationship eventually broke down and was formally ended in 1800.