It’s clear that the Deep South states seceded because Lincoln had been elected, and they saw that as a threat to slavery and an indication that the northern states intended not to abide by the Constitution in that regard. The Middle South states, however, did not secede until Lincoln began to take unconstitutional actions to put down Deep South secession.
The best book on the Deep South is Charles B. Dew’s Apostles of Disunion…, and the best book about Middle South secession is Crofts’ Reluctant Confederates….
