Sorry to point out another error, my friend, but what South Carolina declared was they were seceding for two principles: "the right of a State to govern itself; and the right of a people to abolish a Government when it becomes destructive of the ends for which it was instituted." The South Carolina Convention further declared, "The guaranties of the Constitution will then no longer exist; the equal rights of the States will be lost."
Respectfully,
D J White
South Carolina's Declaration of Secession says the main reason for secession was to preserve slavery.