I’m highly doubtful that a second Civil War would be like the first. I’m more of the opinion that we’d see something along the lines of the Troubles in Ireland.

Maintaining a fighting force requires a ton of money and the loss of international markets in the Civil War hurt the Confederacy greatly. Inflation in the Confederacy shot through the roof. Paired with the Union’s successful blockade, the Union securing most rivers, and the Union pretty much destroying every bit of infrastructure in the Confederate States, the Confederacy had massive economic woes that plagued morale.

I’m really doubtful that any State wanting to secede wants to lose access to the US dollar as it would wreck their economy. I just don’t see it being the way the Civil War was fought as it would almost guarantee a repeat.

Wars are fought along a lot more lines than just the ones where bullets matter.