Gen. Cornwallis surrendered his forces at Yorktown to the Continental and French armies on 19 Oct 1781. The news traveled quickly up the North American coast. On 31 October Gen. William Heath, stationed outside New York, described various ways his troops celebrated, including this anecdote:
the company collected had determined to burn Gen. [Benedict] Arnold in effigy for his treachery at West Point; just as they were going to commit the effigy to the flames, one of the company observed that one of Arnold’s legs was wounded when he was fighting bravely for America, that this leg ought not to be burnt, but amputated; in which the whole company agreed, and this leg was taken off and safely laid by.Arnold didn’t have anything to do with Yorktown, of course. But these soldiers apparently wanted to burn something. It was mid-autumn, after all, and that’s when the British had enjoyed their Guy Fawkes bonfires for generations.
It was probably just a coincidence of when the Yorktown news arrived that this New York bonfire took place on 31 October. However, that celebration was a forerunner of how several of the British Empire’s 5th of November traditions eventually shifted to Halloween in America. The Bostonian Society’s online exhibit traces more of the shift.
In 1887, acting on impulses similar to Heath’s soldiers, the Saratoga Monument Association erected a monument to the leg where Arnold had been badly wounded in battle before he defected to the British.