@Didymos Thomas,
Are you guys serious?! So you suppose that all of a sudden everyone 'realized' the cruelty in being the better end of slavery? Today, there is definitely slavery, and we get the better end. We 'realize' this ofcourse, but what difference is that making?
Rationalists 'realize', empiricists empathize. There has to be a reconciliation of the two in order for people to act.
Sure the war may have been the direct result of the growing popularity of Abolitionism(abolitionist perspective becomes the mass and individuals want to realize and become a part of the mass, yet empathize in their own little ways), but if we could talk to these soldiers who did the fighting, I doubt many would tell you they did it because ending slavery was the primary motive.
In fact, based on novels, I got the idea most people didn't want anything to do with slavery. They, for a long time, realized the cruelty in slavery, but there was no desire to empathize other than for impertinent tangents in one's own self interest.
People must've understood that slavery was inevitably going to end, war just made it happen sooner. In an average citizen's mind, it makes more sense not to have a war at all. Without the empathy, there lacks passion, because heart is something spoon-fed nowadays.