However, I dig deeper. Secession was never intended to protect slavery, for secession was the true goal, slavery was a red herring. Secession or disunion was the goal of both the fire-eaters and the abolitionist.
1. As far back as the 1820s there was a movement by idealogs of seperation of North and South. Several different causes were tried and failed (nullification, state admissions, foreign wars) but the one that stuck was the issue of slavery. See Andrew Jackson's own words on the subject.
2. Secession actually accerated the end of slavery, it could not protect it, it could not expand it, it could not control it. This was obvious to many Southerners, especially slave owners.
3. The wording of documents constantly expressing the devotion to the slavery cause is an overblown attempt to remind people what they were angry about, this practice evaporates from the bulk of official documents and the media after Fort Sumter.