“So the southerners who rebelled - and proudly said it was over slavery - were “leftards”?”
No, but people who think the wartime bluster of a *few* slaveholders represents the thinking of the whole Confederacy have been deceived by leftards.
And there’s no justification for putting “leftards” in danger quotes. It is both accurate and appropriate.
Since there were no polls there can be no consensus of “the whole Confederacy” but it was clearly the sentiment of the leadership that slavery was their primary motivation. I don’t think that they were “leftards” - just wrong.