Agreed, I don't actually think it'd be a geographically clean, traditional war. I'm just assuming the scenario assumed in the meme. That set of states versus the other set of states...who wins?

I don't think the right-wing larpers are necessarily super organized, agreed, but that they at least have arms (including surprisingly powerful stuff), military vehicles, camo, and a lot of them were in the military and very devoted.

Also the 18th century was basically a different world. They didn't have tanks, aircraft carriers, planes, etc. It's like how people assume Julius Caesar completely dominated the Gauls because he was from the more advanced culture. Certainly he won and he was always going to win, but since the tech level differences were smaller, it was a much harder battle than we in the modern day can truly appreciate.

So an actual civil war along these lines would involve half the military fighting the other half, with regular citizens being conscripted and sent to the front lines. It's at the front lines that the more gun-savvy and militiamen will have an advantage over the left. For the people not fighting, the conservative faction will simply shut off the roads, railroads, electricity, supply chain, and food for the enemy.

In actuality, I think any "civil war" would probably be more like small insurgencies that the government as a whole would try to take down, and it's not going to resemble the first american civil war in a "cleanly geographical" way.