In 1777, the British sent Burgoyne's invasion force from Canada south to New York to seal off New England. Their aim was to isolate New England, which the British perceived as the primary source of agitation. Rather than move north to support Burgoyne, the British army in New York City went to Philadelphia in a major case of mis-coordination, capturing it from Washington. The invasion army under Burgoyne was much too slow and became trapped in northern New York state. It surrendered after the Battles of Saratoga in October 1777. From early October 1777 until November 15, a siege distracted British troops at Fort Mifflin, Philadelphia, Pennsylvania, and allowed Washington time to preserve the Continental Army by safely leading his troops to harsh winter quarters at Valley Forge.