Which American victory helped persuade France to ally with the United States in 1778?

The American victory at the Battle of Saratoga helped persuade France to ally with the United States in 1778.

The Saratoga campaign took place in 1777 in northern New York. American forces forced British General John Burgoyne to surrender his army at Saratoga on October 17. The outcome demonstrated that the rebellion could defeat a major British field force.

France had already provided covert assistance, but Saratoga changed the diplomatic calculation. In February 1778, France formally recognized the United States and signed treaties of alliance and commerce. French military, naval, and financial support became crucial to the American war effort.

Saratoga is sometimes overshadowed by Yorktown, where British General Cornwallis surrendered in 1781. Yorktown was decisive in ending major combat, but Saratoga was the earlier victory that helped secure France as an open American ally.