The Battle of Saratoga was the 1777 American victory that persuaded France to formally support the Revolution.
The Saratoga campaign took place in northern New York. British General John Burgoyne led an army south from Canada, aiming to divide New England from the other colonies. American forces stopped his advance, and Burgoyne surrendered at Saratoga on October 17, 1777.
Saratoga mattered beyond the battlefield. The surrender demonstrated that the Continental Army could defeat a major British force, making the American cause appear viable to European observers. France had already supplied secret aid, but the victory encouraged the French government to enter an open alliance.
The Treaty of Alliance with France was signed on February 6, 1778. Saratoga is therefore often described as a turning point, although the war continued for several more years. It should not be confused with Yorktown, the later campaign whose British surrender led directly toward peace negotiations.