Shera said:
I've personally always found it incomprehensible how the Southern elite managed to get the rest of their countrymen to support them in a war that was against their interests.
Because it was about a whole lot more than just slavery. The protectionists tariffs hurt the poor farmers and families a lot more than it did the elites. In fact, the biggest reason for the increasing rift between the northern and southern states throughout the first half of the 19th century was the tariff issue.
Then there was the issue of creeping Federal power, which the northern states liked because they were the majority in both houses and the southern states didn't like for the same reason.
But even then, they ultimately didn't cry war, just secession. If Lincoln hadn't sent in the troops, and had surrendered Fort Sumter like he did the rest of the military bases, no one would have been attacked. The South was on the defensive.
But this was not the cause of the Civil War. Like you say Tariffs caused a strain in relations only in the first half of the 19th century, not the latter.
Only one state threatened to leave the Union over tariffs and that was South Carolina in the 1830s. SC and the Federal government were able to reach a compromise. The tariffs rate were lowered and the federal govt wast still able to use tariffs to nurture a growing manufactuing base that could not hope to be competitive against the more established and mature European one for quite some time. Many politicians were in favor of the tariffs because they wanted a strong manufacturing base in the advent that the nation had to go to war again.
I have a transcript of the Lincoln Douglas debates in 1858 by Holzer. In the seven debates that each occurred over many hours (attention spans were longer then

) Douglas only mentions Tariffs a few times, and each time it was only to cite it as an example of one of the differences between the Whig and Democratic parties that stopped being an issue after 1850.
As for "creeping Federal power" -- it was supportive of the Southern States right to have slavery within their own borders. Congress even passed a law requiring law enforcement in the Northern States to cooperate and return runaway slaves to their Southern owners. (
Fugitive Slave Act of 1850)
IMHO, the Southern States succeeded after Lincoln won the presidency because even though he had said that he would do nothing to interfere with the institution of slavery within the South, they didn't believe him. In the debates, when asked, he would say that he believed that eventually the USA would be entirely all free or all slave. As a result I don't think the Southern states trusted that he wouldn't do anything to interfere with slavery. But ironically, if they had not succeeded from the Union, there is no reason to believe (based on his previous statements, actions and personal beliefs) that Lincoln would have.
So I still stand by my opinion that it was not logical for the 66% (based on Mike B's links which uses 1860 census statistics) or the 75% (based on the Sparknotes link in my post #60 which probably used the 1850 census statistics) of the white southerners who didn't own slaves to support their wealthier neighbors by joining them in the Civil War.
The real reason that the southern non-slave owners may have supported the war was because growing up and being indoctrinated in a stratified society it was no doubt of great importance to them that they were not in the absolute bottom social tier. But I'm straying too far away from the OP ...