Greg Bear wrote a book called "Fire on the Mountain".
Where exactly that happens, but it's a mass slave revolt. As bad in it's own way as Ward Moore's "Bring the Jubilee", and "Man in the High Castle". Things happen for no real reason, a handful a volunteers break what would have been a blockade that would have been airtight, Mexico suports the slaves when she had almost no government and was about to be invaded by France, Britain, and Austria. And as for "Man in the High Castle", it's not really an alt at all, just a what if with no reason for the Axis' power's victories.