Take a look at this map.
As the article in Ranker.com states, this is a map produced by the US Coast Survey which depicts the proportion of the residents of each county in the South who were slaves, the darker the shading, the higher the percentage of slaves. The darkest areas, along the Mississippi and some other regions, were counties with more than ninety percent of their population in bondage. This map clearly shows the extent in which the rural South had become dependent on slave labor, particularly in those regions most suitable for the establishment of large plantations. In many such regions, the Black slaves outnumbered the White population. The population of slaves in such urban regions that existed in the Old South along with areas, such as the Appalachian Mountains and West Texas that were ill suited for plantation agriculture was far lower.
While interesting in itself, this map of slavery might also provide an clue which tells us just what why the South seceded and what they were really fighting for in the Civil War.
It is not easy to determine just how many people in the South actually were in favor of secession. Public opinion polls did not exist yet. In most cases, the Southern states seceded by calling for special conventions of elected delegates, who voted on the question of secession. Obviously, the men who were sent to these conventions were already predisposed to be in favor of secession, but the actual votes were closer than one might expect, given the controversy that the election of Abraham Lincoln had produced throughout the South. It is possible that if enough time had been allowed for passions to cool, and for the Southern leaders opposed to secession to organize, the secession crisis might have been averted. As it was the Secessionists moved quickly and there is evidence that they acted to intimidate opponents of succession in some areas.
Still, while support for secession was far from unanimous in the South, it is likely that a majority of the people throughout the South did support secession. There was considerable regional variation, though. In general, it seems that the support for secession was greatest in the seven states of the Lower South who were the first to secede. There was likely less support for secession in the four states of the Upper South which succeeded later, as war became imminent Eastern Tennessee and Western Virginia were notorious for their pro-Union sentiments, and the western counties of Virginia themselves succeeded to form the state of West Virginia. Of the four slave states that stayed in the Union, only Delaware with almost no actual slaves had no movement towards succession, while the remaining three had at least enough people opposed to succession to keep their states in the Union, although there was enough support for succession in Missouri and Kentucky for there to be a Civil War within each state.
Now, if you look at that map of slavery again, you may notice that, in general, support for succession tended to be highest in those regions that that were most dependent on slave labor. Since the end of the Civil War, there have been those who have argued that secession and the Civil War were not about slavery. The Civil War was fought over states’ rights or the economic policies of the North, particularly the high, protective tariffs Northern manufacturers favored. This map gives the lie to such assertions. Support for the Confederacy was highest where slaves were most numerous. Where slavery was rare, so was enthusiasm for secession. If you don’t believe what the Southern leaders themselves said about their reasons for succession, believe what the map shows, a clear link between slavery and succession.
That is not to say that slavery was the only cause of the secession and Civil War, nor that the men who fought for the Confederate States did so in order to protect the institution of slavery. There were a lot of other factors, both political and economic, behind the sectional tensions between North and South, but slavery was the one issue that made compromise impossible. They might be able to meet each other half way on issues like tariffs, but slavery was a moral issue which aroused people’s emotions. The country could not remain half slave and half free. It is true that most of the men who enlisted in the Confederate Army were only fighting for their country, but the way wouldn’t have been fought at all if it were not for slavery.
The American Civil War was fought over slavery. There is simply no way to deny it without completely ignoring the historical evidence. The men who fought for the South May have been brave and honorable, but they were fighting for the worst cause imaginable.