My research tells me the Southern states in rebellion seceded to defend slavery.
“The new Constitution has put at rest forever all the agitating questions relating to our peculiar institution—African slavery as it exists among us—the proper status of the negro in our form of civilization. This was the immediate cause of the late rupture and present revolution.”
Alexander H. Stephens
Vice President, Confederate States of America
If that is the only thing you are going to look for, that is the only thing you are going to find. And it's irrelevant anyways. The Southern states had a right to leave for any reason they liked, even if it was a reason of which *YOU* disapproved.
The Northern states had no right to invade and murder them because they were leaving and the Northern states had no right to pretend they did it because of "slavery", when they really did it because of money.
The deceitful Northern states passed the Corwin Amendment which would have protected slavery indefinitely. The Northern states would give them all the slavery they could want, but they would *NOT* allow the Southern states out of their economic control.
The War was about money which would have been lost to the north.