Exactly which human rights was it that the south had access to? You have me confused there.
There had already been a movement to send blacks back to Africa, which is how Liberia came into existance. And I think there had already been a belief that slavery would "die out on its own anyway," which is probably one of the reasons it was not confronted at the time the constitution was being written, aside from the fact that many at the convention owned slaves. In any case, it didn't die out on its own. Also, ending slavery didn't bring Great Britain into the war. And slavery was still viable and probably would be today.
None of that has anything to do with guns, though, now does it?
Shoot low, sheriff. They're riding Shetlands!
Underneath the starry flag, civilize 'em with a Krag,
and return us to our own beloved homes!
Buy War Bonds.