Interesting, I'll add that to my growing list of "Confederate attacks in states not directly adjacent to the Confederacy-proper".
So far I have California, Arizona, Colorado, Kansas and now Vermont.
I also question how many Confederate-sympathizers were involved in the New York City draft riots of 1863.
My reasons are: a) the number of blacks who were lynched -- what's up with that? plus b) the overall destruction seems more than the occasion itself called for, and c) strong pre-war commercial ties between NYC and the South, lots of people thrown out of work by the war.
Now, change history just a little bit, and put those NYC draft riots in the context of a Robert E. Lee victory at Gettysburg, imagine Lee has met his first objective and now sits encamped on the railroad junctions at Harrisburg, PA -- and don't things start to look pretty ugly?
I'm just saying... ;-)
Whether that really would have happened, considering probable additional battles in PA, we will never know.