Prefacing my post with a quote from Abe Lincoln.
"I have no purpose to introduce political and social equality between the white and black races. There is physical difference between the two which, in my judgment, will probably forever forbid their living together upon the footing of perfect equality, and inasmuch as it becomes a necessity that there must be a difference, I, as well as Judge Douglas, am in favor of the race to which I belong having the superior position."
See more Lincoln quotes after the post.
The South had an economy stronger than the North. The South exported, while the North imported. The South leaving the Union and the Union demanding the South stay is strong evidence that the South did not need the North, but the North needed the South.
The South had no interest in taking over the North, so the name "Civil War" is a misnomer. It was much more about economics than the disingenuous high ground the North tried to present. The two regions were economically different. The South had all the resources in raw materials. The South's raw materials dominated the US economy. They provided 2/3 of the world's cotton. The tariff was an ongoing issue. First in 1828. The last straw was the Morrill tariff of 1861.
The North sought industry protection instead of letting people freely choose where they would buy their goods. The South had the wealth and their exporting was hurt by the tariff. The North could not freely compete with the rest of the world.
England and Europe favored the South because they did not favor the tariff. Lincoln knew he could not sell the war internationally on the tariff/economics, so he played the slavery card. England (rightly) opposed slavery, so the US government played that angle. Most people did not really care about slavery, at least to the point of killing one another over it. Lincoln was a shrewd and insincere racist who just manipulated the slavery angle. If the South had not been so greedy and just given up their slaves, then the North would not have had an argument. It was a poor decision on their part, but they were greedy. Their economy would have been better than, or at least equal to, the North because of their raw materials, even without slavery.
More Lincoln quotes:
“I will say then that I am not, nor ever have been in favor of bringing about in any way the social and political equality of the white and black races.”
"And inasmuch as they cannot so live, while they do remain together there must be the position of superior and inferior, and I as much as any other man am in favor of having the superior position assigned to the white race.”
Lincoln was not interested in freeing slaves: “I have no purpose, directly or indirectly, to interfere with the institution of slavery in the states where it exists. I believe I have no lawful right to do so, and I have no inclination to do so.”
“There is a natural disgust in the minds of nearly all white people to the idea of indiscriminate amalgamation of the white and black races … A separation of the races is the only perfect preventive of amalgamation, but as an immediate separation is impossible, the next best thing is to keep them apart where they are not already together. If white and black people never get together in Kansas, they will never mix blood in Kansas…”