You do realize that I actually live in the area, making it not of theoretical interest in my personal experience.

They definitely don't have access to the sea, however. That is an isthmus-protected large bay, yes – but as depicted it would be entirely under the control of the Union on the north side of the bay, and well within the range of the canons in the northern parts of North Carolina. Nothing would get in or out without the tacit approval of both sides, and that's before we factor in whether or not the South decided to actually build up a more significant naval force as a result.

Foreign sympathizers is great, but they can't get the support there, neither from the north nor the south because that is a lot of land to cross, so whoever they're bringing it from has to be also be buying off one side or the other.

Coal they certainly might have, but that's only going to make them a protected trading partner from the north with the factory production of the Union historically, and much less interesting to those in the South who are largely agricultural. Food being a resource that your Republic of Zion is going to be terribly short on.

While simultaneously robbing the north of a lot of what would become inner-city cheap factory workforce, while we're at it.

And let me tell you – "socialist and labor-oriented policies" were not the socialist and labor-oriented policies you are familiar with. And they have always been actively and grossly contentious, largely oppositional to the Jacksonian political inclination of the region.

Let me look outside real quick.

Nope, still very much like that.

This would be very much like me suggesting that Provençal became a breakaway slave state established by escaping Moorish and North African slaves, fully accepted by the locals, except that Provençal actually has pretty decent transport access.

For all that we suggest that game designers should learn European history before writing northern European fantasy, we also have to support that European game designers should learn American history before trying to write North American fantasy. If we don't, what good are they?