[Non-Sequitur]

Slavery was wrong. It would have disappeared from the South under far friendlier terms had the Confederacy survived.

But none of the southern leaders of the period agreed with that, nor did virtually any of the white southern population as a whole.

[=Intervention=]

One in ten people who could own slaves in the South, did. You must also bear in mind that slavery wasn't just a Southern thing. It existed in most states of the Union. I daresay that precious few of those in the North thought of blacks as equals -- Lincoln sure didn't.