Which battle's American victory helped persuade France to enter the Revolutionary War as a U.S. ally?

The Battles of Saratoga's American victory helped persuade France to enter the Revolutionary War as a U.S. ally.

The Saratoga campaign consisted of two major battles near Saratoga, New York: Freeman's Farm on September 19, 1777, and Bemis Heights on October 7. The British force, commanded by General John Burgoyne, surrendered on October 17 after becoming isolated and outnumbered.

The victory demonstrated that the Continental Army could defeat a major British field army. It also strengthened American diplomacy in Europe. France had already provided secret assistance, but Saratoga helped convince King Louis XVI's government that the American cause had a realistic chance of success.

France then signed the Treaty of Amity and Commerce and the Treaty of Alliance with the United States on February 6, 1778. French money, troops, ships, and military supplies became especially important later in the war, including during the campaign that led to the British surrender at Yorktown.