The South had developped a unique society and a sense of Southern nationalism. The conflict with the North and the secession were an attempt to create an independent nation. Also a contrast, the South having developped a class system whereas the North was characterized by a social structure.
Ante Bellum South
A Southern ideology -based on aristocracy- justified slavery. Many (crazy) explanations were put forward like: "the African race is biologically inferior" or "physically and mentally under-developped". Through slavery, they could adjust to a better kind of life, be taught new morals and the "true religion". All that was part of the Southern ideology: "some people must work and sweat to provide those in charge with leadership". The Southern society is hedonistic when the North advocates the puritan ethic (moral - virtue - hard work, according to the Bible).
After 1830, abolitionists societies began violent campaigns against slavery. Garrison was an extremist abolitionist who printed/invented sensational stories about how cruelly black slaves were treated in the South. Slave holders were depicted as monsters and, in the North, slavery was seen as a sin against God (move on to the religious ground). Garrison wanted the "purification of the Nation from the guilt of slavery".
Slavery is the apparent cause of the Civil War: it was the spark that ignited the powder-keg. Yet, it should be obvious that the real cause of the conflict was the incompatible and irreconcilable economical, political, social and ideological difference between the 2 sections.
The South's economy relied on agriculture. The North kept taxing the Southern imports from Europe, hoping that the South would buy Northern products that were overpriced and more poorly manufactured. In retaliation, Europe raised prices on their imports, making it very expensive to purchase Southern cotton and tobacco. Since the US Government had Northern majority in the legislature, the South could do nothing except to be taxed. Before the outbreak of the war, Southern planters were paying 87% taxes on their goods. Enraged by only being able to keep 13% of their profits, the Southerners knew the government would not help and that they had to act.
As the 19th century slipped by, North and South drifted further and further away until the moment they had nothing left in common, not even a President. This is when the war broke out. Five years later, the South was defeated, conquered, occupied, Southerners were humiliated and slavery was at last abolished. The situation of the South was not unlike that of Nazi Germany at the end of World War II. Southerners were despised and shamed. The same questions were asked: how could people be slave holders/nazis ? Hence a feeling of guilt in the South.
On the other hand, many Southerners did not acknowledge their inhumanity and monstrosity. In order to justify themselves, they idealized the "Old South". This theme will later be pick up in literature, for instance in Gone with the Wind or in the personality of Faulkner"s characters, who cannot overcome their guilt but who realize they are the descendants of a cursed race.
Events leading to secession
In response to the events in Kansas (with the creation of the Republican Party), extremist parties began to emerge. Before the KKK, there has been a party with a strange name, the "Know-Nothings", which originated from secret political orders. The movement originated in New York in 1843 when it was called the American Republican Party. It spread to other states as the Native American Party and became a national party in 1845. In 1855 it renamed itself the American Party. The origin of the "Know Nothing" term was in the semi-secret organization of the party. When a member was asked about its activities, he was supposed to reply, "I know nothing." They were organized to oppose the political influence of immigrants (mainly Irish and Germans) and the political machine allowing such immigrants to vote. As a nationalist anti-foreign movement, it organized later under the name "American Party". It was hoped it would become a national party but as a matter of fact, it disintegrated after the elections of 1856.
In 1856, the Democrat James Buchanan was elected President. He favored popular sovereignty and won an easy victory over his opponent.
Several events during the Buchanan administration convinced the Southerners they would not be able to protect their interests any longer against the majority of Northerners. Secession seemed to be the solution.
The Dred Scott case of 1857 and the Missouri Compromise judged unconstitutional delighted the South. The Republicans denounced it as partism since several justices in the Court were Democrats. As the decision had no legal justification, the North refused to accept it. It alarmed the South.
1857: panic, sharp depression. The South suffered much less than the industrial North, gained confidence and asserted that this proved the "superiority of Southern economy". During the elections of 1857, the North voted strongly Republican and gave this party the lead in the House of Representatives. The series of debates between Lincoln and Douglas for the senate elections aligncenter on the slavery question. Douglas was the incumbent senator and Lincoln the challenger. At Freeport, Lincoln tried to embarrass Douglas by asking if the people of the territories could legally exclude slavery. Douglas, in his response called the "Freeport Doctrine", replied that people of the territories could keep slavery out by not passing local police regulations, necessary for its existence.
Douglas won but his answer did not satisfy the South and helped to widen the growing split between North and South Democrats. Thanks to these debates, Lincoln was popularized and won the presidential nomination in 1860. 1859: John Brown's raid. After his execution, the North made a martyr of him.
1860: the elections were the last event before the war. The Democrats met in the Supreme Court. There, the Southern extremists demanded that the party ask Congress to guarantee slave property in the territories. The North under Douglas defeated the demand and adopted Douglas" policy of popular sovereignty. The South made a clash.
The Republicans met in Chicago. Lincoln was chosen because he was the most moderate candidate. His platforms promised to exclude slavery from the territories.
Lincoln won every states in the North (except New Jersey) but he gained only a minority of popular votes. Another candidate won a state in the lower South. The rest was won by extremist candidates. The South declared that Lincoln's election would be the signal for secession. Lincoln was elected and the South proceeded to secede.