One third of the Southern population already had freedom denied it. The other two thirds were bound and determined to make sure it stayed that way. I'd say hypocrisy was just as prevalent in the Southern cause as you say it was in the Northern cause.
And you’d be wrong given that slavery was a U.S institution and would (and for a while, did) continue to exist in the U.S. You have to be intellectually honest and admit that the war was fought to preserve the union, NOT free slaves, just as Lincoln said.