Veteran here. Speculation - take it for what's it's worth (not shit). There's a weird notion that the military is always just going to default to red, and while the total count definitely does lean red (cuz, y'know... most of us are fuckin dumbasses who vote against out own interests...) there IS a split... maybe... idk, 60-40? Point is there's a lot more blue in the military than we're typically painted as.

So, civil war. First off, not gonna happen cuz we don't have the spine for it. We'll just continue to bitch at eachother from the comfort of our couches; and while that bitching will probably get louder and we'll probably see some increase in domestic terrorism, it will not get to the point of actual war. But if we did... the military isn't going to just pick a side; it'll turn into the world's largest shitshow of infighting. Then once we've sufficiently hamstrung ourselves, we're going to get our asses handed to us by the enemies across the globe we've been collecting like fucking pokemon via our shitty foreign policy.

Tldr, the sides of our civil war are basically two yipping lapdogs that will bark louder and louder at eachother until we eventually prompt our pissed off neighbor to come over with a shotgun. The actual war that happens will kill both dogs well before we get to the point of a civil war.