The Battles of Saratoga are widely called a turning point of the American Revolutionary War because they helped bring France openly into the conflict.
The campaign consisted of two major battles near Saratoga, New York, on September 19 and October 7, 1777. American forces ultimately forced the British army commanded by General John Burgoyne to surrender on October 17.
The victory demonstrated that the American cause could defeat a major British field army. France had already been secretly supplying the Americans, but news of Saratoga encouraged King Louis XVI's government to formalize support. The United States and France signed the Treaty of Amity and Commerce and the Treaty of Alliance on February 6, 1778.
Saratoga is sometimes described as one battle, but the name properly refers to the campaign's two principal engagements. Yorktown came later, in 1781, and was decisive but was not the event that first secured France's formal alliance.