Nope, sorry. It was slavery. Dressed up in the noble robes of States' Rights, but largely about the right of states to permit slavery.
Surely the Vice-President of the CSA knew what he was talking about when he said:
(Our new government's) foundations are laid, its corner-stone rests, upon the great truth that the negro is not equal to the white man; that slavery-subordination to the superior race-is his natural and normal condition. This, our new government, is the first, in the history of the world, based upon this great physical, philosophical, and moral truth.
But let's not take his word for it. South Carolina listed a Declaration of the Immediate Causes Which Induce and Justify the Secession of South Carolina from the Federal Union , in which they listed... the US Government's hostility to slavery.
They weren't the only ones, though. Georgia created a similiar document. It begins:
The people of Georgia having dissolved their political connection with the Government of the United States of America, present to their confederates and the world the causes which have led to the separation. For the last ten years we have had numerous and serious causes of complaint against our non-slave-holding confederate States with reference to the subject of African slavery.
Took them two whole sentences to get to the point.
Mississippi's was similarly direct, opening with:
In the momentous step which our State has taken of dissolving its connection with the government of which we so long formed a part, it is but just that we should declare the prominent reasons which have induced our course.
Our position is thoroughly identified with the institution of slavery-- the greatest material interest of the world.
And finally - Texas, not to be outdone, wrote its own declaration.
Texas abandoned her separate national existence and consented to become one of the Confederated Union to promote her welfare, insure domestic tranquility and secure more substantially the blessings of peace and liberty to her people. She was received into the confederacy with her own constitution, under the guarantee of the federal constitution and the compact of annexation, that she should enjoy these blessings. She was received as a commonwealth holding, maintaining and protecting the institution known as negro slavery-- the servitude of the African to the white race within her limits-- a relation that had existed from the first settlement of her wilderness by the white race, and which her people intended should exist in all future time.
Look, I'm sympathetic to a bunch of noble freedom-fighters who recoil against Federal control and rebel in the name of liberty, but these guys weren't that. They were fighting to preserve their state's right to own slaves.
Well? Make up your mind, darn it. Was it or wasn't it? Largely means it is part of something more. :-)
And finally - Texas, not to be outdone, wrote its own declaration.
Texas should have simply renounced the 1845 Treaty and reclaimed its status as a Republic. That unique status kinda separates us from everybody else except Hawaii.