The 1777 American Revolutionary War event near Saratoga, New York, that helped persuade France to ally with the United States was the Battles of Saratoga.
The Battles of Saratoga consisted of two major engagements in the Saratoga campaign: the Battle of Freeman’s Farm on September 19, 1777, and the Battle of Bemis Heights on October 7. American forces under General Horatio Gates opposed the British army commanded by General John Burgoyne. Burgoyne surrendered his army on October 17.
The American victory demonstrated that the rebellion could defeat a major British force. France consequently became an open American ally, signing the Treaty of Amity and Commerce and the Treaty of Alliance in 1778. French military and financial support became a major factor in the eventual American victory.
A frequent source of confusion is the wording. “Saratoga” can refer to the two battles, the wider Saratoga campaign, or the surrender that followed. The Battles of Saratoga are the specific engagements most often identified as the war’s turning point.