September 19 & october 7, 1777
The "Battle of Saratoga" [referring to Saratoga County, New York] actually may be broken into two separate clashes, three weeks apart. The first took place on September 19, 1777 at Freeman's Farm. The second was at Bemis Heights on October 7.
The Battle of Saratoga was fought on two dates: September 19, 1777, and on October 7, 1777.
The Battles of Saratoga in September and October 1777 were decisive American victories in the American Revolutionary War, resulting in the surrender of an entire British army of over 6,000 men invading New York from Canada. This action, often referred to in the singular as the "Battle of Saratoga", was actually two battles fought eighteen days apart, but on the same ground, nine miles south of Saratoga, New York: the Battle of Freeman's Farm on September 19 and the Battle of Bemis Heights on October 7.
Forced to retreat after his defeat on October 7, General John Burgoyne and his entire army surrendered ten days later after being surrounded by much larger American militia forces. The capture of an entire British army secured the northern American states from further attack via Canada and prevented New England from being isolated. A major result was that France entered the conflict on behalf of the Americans, thus dramatically improving the Americans' chances in the war. The battles of Saratoga, and the entire Saratoga campaign that concluded with the surrender of Burgoyne, are commonly seen as the turning point of the Revolution.