If a sitting prez is about to launch one half of this nation against the other (and I don't care what the reasons are) and anyone who doesn't go along with it like a lapdog is a "traitor" in your opinion, then you're sheeple pure and simple.
6 million dead in today's numbers folks! Go into Manhattan and murder everyone in it and you're still not even close.
But the southern position is that they weren't half of the nation anymore. They were a separate nation.
The sitting prez did NOT "...launch one half of this nation against the other...". He did, much to your chagrin, respond to attacks on American forces as any president MUST.
If you have any concern about the death toll you should place the blame for it where it belongs - on the Slaver ruling class of the South as sorry a set of dogs as ever roamed the earth.