U.S. slaves by the thousands left went British forces in both the Revolutionary War and the War of 1812 to be set free. The actions like these caused legal actions by the United States against Great Britain for compensation for stealing slaves.
Prior to Floridas purchase by the United States, that Spanish territory was a refuge for runaways from Georgia, and it was draining that slave state dry of slaves and making its southern boarder unstable. Military forces were sent several times to exterminate the growing population of runaways in that region (The Battle of Negro Fort). By acquiring territory, and passing laws giving protections to the slave, and protections to slave owners property, the slave states created an institution that was fairly stable in controlling the slave populations.
By 1860, the slaves new the end was near, and were passively waiting for it to come. Even though they were not supposed to understand, they new of the abolitionist debates as clear as any person with the skills to read. With a Republican controlled Congress, and a large majority of states, slavery could be easily removed as a state right as it was in 1866. Where would that leave the original seven seceding slave states? With a small free population and an extremely large bonded population boardered, on two sides by large free nations, a border thousands miles long, the institution would eventually have collasped, most probably from the shear cost to maintain the institution, and the cost of doing business with foriegn nations because of the import dependent economies of these slave states.
The leaders of the 1860 secession knew this, they had to, whatever their cause it was not inline with the wants of the Southern unionist majority. All of this changed when Lincoln called to invade the South in 1861. He wasn't just attacking the slave owners, he was attacking the South. When the common Southerner realized all would be lost, and realized the decades old myth was wrong and slaves really wanted to be free, you start seeing the calls for negro troops in the South. By this time they didn't care about the slavery institution and those who prospered from it, they wanted their rights, protections and independence more. This is most probably why the leaders of the original secession movement are not known or remembered in the South, they were cast aside for real men of vision.