They went to "Independence" for that reason. They went to war because they were arrogant. As long as we are being picky, let's get it right.
They didn't care that he said that he wouldn't steer any effort at ending slavery - only keep it from spreading. The south's primary motivation wasn't independence - it was control.
Control of what? Their own States? Yeah, I think that's pretty much the point. They even were willing to give up slavery (toward's the end) to keep Independence.
There was no violent repression of anyone except for that which the south perpetrated against its neighbor.
And what violent repression of their neighbor did they commit? Who did they bloody or kill?
Make me laugh. That simply never happened. Even when the confederacy passed a resolution, by a razor-thin margin, a couple of weeks before surrender to recruit black soldiers, they included a clause that "nothing in this act shall be construed to authorize a change in the relation which the said slaves shall bear toward their owners, except by consent of the owners."