That feeling was not universal, especially in the North that had more interstate infrastructure and an integrated economy. But many Southern officers stayed in the US army. Lee chose. He put himself where he wanted to be.
Well yes, but the tie to your state was stronger then it is now, and states did have more power. I mean hell, local history time...
The army engineer that came from Mass. to build For Pickens went hard core slave owning local. But quick thinking on the part of the people in charge meant that Pensacola itself was maybe confederate for a few weeks, if that? [And after the war, the locals were really pissed when the Gov of Florida put up confederate monuments in town, according to my spouse.]
So, like there were northerners who went with the South and insurrection too. The point being...
Trump actively started this shit - Lee chose the wrong side, but he did not start the war - in fact, the war started before Virginia decided to join the south. [Like wtf but whatever].
And Lee was a good, capable general, Twitler isn't.