You have a quote or something? If they were going to war for Slavery, I would have thought their first attack would be at the Capitol in DC. Was Fort Sumter the seat of all the Anti-Slavery activity or something?
The new Constitution has put at rest forever all the agitating questions relating to our peculiar institutions—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. Jefferson, in his forecast, had anticipated this, as the “rock upon which the old Union would split.” He was right. What was conjecture with him, is now a realized fact. But whether he fully comprehended the great truth upon which that rock stood and stands, may be doubted. The prevailing ideas entertained by him and most of the leading statesmen at the time of the formation of the old Constitution were, that the enslavement of the African was in violation of the laws of nature; that it was wrong in principle, socially, morally and politically. It was an evil they knew not well how to deal with; but the general opinion of the men of that day was, that, somehow or other, in the order of Providence, the institution would be evanescent and pass away... Those ideas, however, were fundamentally wrong. They rested upon the assumption of the equality of races. This was an error. It was a sandy foundation, and the idea of a Government built upon it—when the “storm came and the wind blew, it fell.”
Our new Government is founded upon exactly the opposite ideas; its foundations are laid, its cornerstone 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 moral condition.
Alexander Stephens. pretended VP of the pretended confederacy
To be fair, they did attempt to assissinate Lincoln in Maryland. Further, they attempted to stuff DC with slave power militia units to prevent Lincoln from being inaugurated.
Fortunately Pinkerson sniffed out the assassination attempt, and loyal US Army officers went around to the militia companies demanding that their officers execute a loyalty oath in front of their men. Those that refused were disbanded, the weapons collected, and the weapons issued to loyal companies.
"What did we go to war for, if not to protect our property?" - CSA senator from Virgina, Robert Hunter, 1865
What was the reason that induced Georgia to take the step of secession? This reason may be summed up in one single proposition. It was a conviction, a deep conviction on the part of Georgia, that a separation from the North-was the only thing that could prevent the abolition of her slavery. -- Speech of Henry Benning to the Virginia Convention
History affords no example of a people who changed their government for more just or substantial reasons. Louisiana looks to the formation of a Southern confederacy to preserve the blessings of African slavery, and of the free institutions of the founders of the Federal Union, bequeathed to their posterity. -- Address of George Williamson, Commissioner from Louisiana to the Texas Secession Convention
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. --Mississppi Declaration of the Causes of Secession
"[Recruiting slaves into the army] is abolition doctrine ... the very doctrine which the war was commenced to put down." - Editorial, Jan 1865, North Carolina Standard