Yes, the last time was the “War of Northern Aggression” in 1861. But this one will be the War of Socialist Aggression! The largest armed population in the world is the American public.
I believe the operative model for the Feds will be Sherman’s concept of “Total War.”
It's not going to be pretty. Nothing can be as bloody as a national feud. And nothing will be so complete as the rooting out of every single person who thinks they can escape the true justice of what the U.S. Constitution terms, capital "C", "Citizens."
Just ask the Gods of the Copybook Heading, who originally penned the phrase, "What goes around, comes around."