I find it hard to believe that you can’t see the moral distance between treating a group of people badly and treating a group of people like property. Hell I know it’s an axiom of arguments that you lose as soon as you mentioned the Nazis but I will say that the fact the confederates didn’t want to exterminate blacks put them morally above the Nazis who wanted to exterminate groups of people.
The fact you are unwilling to accept is that believing all men should be free, as Abraham Lincoln did from an early age, put him morally head and shoulders above any leader of the southern rebellion. Here is an excerpt from a letter he wrote to his good friend Joshua Speed (who was a slave owner) in 1855 where he talks about the trip they took down the mississipi river in their younger days. Read it and tell me that isn’t a man who is deeply upset by the injustice of slavery.
“you know I dislike slavery; and you fully admit the abstract wrong of it... I also acknowledge your rights and my obligations, under the constitution, in regard to your slaves. I confess I hate to see the poor creatures hunted down, and caught, and carried back to their stripes, and unrewarded toils; but I bite my lip and keep quiet. In 1841 you and I had together a tedious low-water trip, on a Steam Boat from Louisville to St. Louis. You may remember, as I well do, that from Louisville to the mouth of the Ohio, there were, on board, ten or a dozen slaves, shackled together with irons. That sight was a continued torment to me; and I see something like it every time I touch the Ohio, or any other slave-border. It is hardly fair for you to assume, that I have no interest in a thing which has, and continually exercises, the power of making me miserable. You ought rather to appreciate how much the great body of the Northern people do crucify their feelings, in order to maintain their loyalty to the Constitution and the Union. … How can any one who abhors the oppression of negroes, be in favor of degrading classes of white people? Our progress in degeneracy appears to me to be pretty rapid. As a nation, we began by declaring that “all men are created equal.” We now practically read it “all men are created equal, except negroes.” When the Know-Nothings get control, it will read “all men are created equal, except negroes, and foreigners, and catholics.” When it comes to this I should prefer emigrating to some country where they make no pretence of loving liberty—to Russia, for instance, where despotism can be taken pure, and without the base alloy of hypocrisy.”
Long before Lincoln's War the states of New York, New Jersey, New Hampshire, Connecticut, Massachusetts, Pennsylvania, Rhode Island, Delaware, and Maryland voted to include slavery into the U.S. constitution. These states voted for slavery along with the states of Virginia, North and South Carolina and Georgia.
And prior to the war not one Congressman or Senator from the northern states - to my knowledge - ever introduced a constitutional amendment to end slavery. Not even Congressman Lincoln.
But there was, of course, a very good reason such an amendment was not introduced: it was not in the economic or political best self-interest of the northern states.