I will allow the actors of the Civil War to make my points for me.
Abraham Lincoln provides us his views on African-Americans:
“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; I am not nor ever have been in favor of making voters or jurors of negroes, nor of qualifying them to hold office, nor to intermarry with white people…
I will say in addition to this that there is a physical difference between the white and black races which I believe will forever forbid the two races living together on terms of social and political equality. 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.” — [Debate at Charleston, Illinois, September 18, 1858]
Confederate General Robert E. Lee had this to say about blacks:
In this enlightened age, there are few I believe, but what will acknowledge, that slavery as an institution, is a moral & political evil in any Country. It is useless to expatiate on its disadvantages. — [Freeman, Douglas S. (1934). R. E. Lee, A Biography]
The fact that Lincoln was an ardent racist, as were his slave owning Union Generals, should tip you off to the fact that the institution of slavery wasn't the root cause of the violent conflict. The U.S. is the only country in the world where a civil war occurred prior to the abolition of slavery. The notion that the abolition of slavery required some kind of war is absurd. In fact, the institution of slavery was on its way out the door prior to the Civil War, and it would have ended all on its own thanks to jury nullification and state nullification of federal laws.
How could this be so?
Confederate General Joseph E. Johnston explains:
... the division of the country would give the slaves of the border Southern States so near and safe a refuge that those states would soon cease to have slaves and be compelled ... to abandon the Confederacy.' — [Craig L. Symonds, Joseph E. Johnston: A Civil War Biography, p. 93]
You see, when a slave state is bordered by a free state, the slaves now have somewhere to run. Just as we saw in East Germany, and countless other socialist wastelands throughout history, people will run to where they are free if they are violently oppressed. My own father escaped from communist Hungary by hopping a fence and running through a minefield into Austria.
In the articles of secession, the South is quite explicit about why they sought to leave the union. South Carolina stated its reason for leaving the union as:
The Constitution of the United States, in its fourth Article, provides as follows: "No person held to service or labor in one State, under the laws thereof, escaping into another, shall, in consequence of any law or regulation therein, be discharged from such service or labor, but shall be delivered up, on claim of the party to whom such service or labor may be due."
This stipulation was so material to the compact, that without it that compact would not have been made....
The General Government, as the common agent, passed laws to carry into effect these stipulations of the States. For many years these laws were executed. But an increasing hostility on the part of the non-slaveholding States to the institution of slavery, has led to a disregard of their obligations, and the laws of the General Government have ceased to effect the objects of the Constitution.
The federal government did not hold up its end of the bargain as far as the Southern states were concerned, so they felt that they had every right to secede from it. The Constitution was a contract, and the feds had violated it by not vigorously pursuing runaway slaves.
Slavery as an institution is impossible without the state imposing it. If the state took no position on slavery, for or against it, the free market could not impose it on its own. There were no electric fences around the plantations in the South. The slaves could have walked off any time they wanted to. What kept them there was the fact that they had no where to run to. Government agents would have set about capturing them if they tried to flee, and anyone who harbored them would have been thrown into prison. Without the state, the cost of keeping a slave tied to a plantation through force would have exceeded the revenues that slave would have generated. Prisons are money losing propositions by nature. They make money only because the state funds them with stolen tax money.
The North aggressed against the South in order to keep the flow of Southern tax money coming into its coffers. If the North had simply let the South walk away from the union, slavery would have collapsed on its own, just as it did everywhere else around the world. While it is true that the South fired the first shots of the Civil War, they only did so because of threats made by the North leading them to conclude that an invasion was imminent.
The Civil War didn't need to happen. It was caused by the pure greed of Northern bureaucrats. The Civil War may have brought about a quicker end to slavery, but it was at the cost of untold misery and hundreds of thousands of lives lost. Further, the war destroyed the concept of a voluntary union of states. Now the states are nothing more than puppet governments which are ruled by the high throne in Washington to the determent of all.
If I could save the Union without freeing any slave I would do it, and if I could save it by freeing all the slaves I would do it; and if I could save it by freeing some and leaving others alone I would also do that. What I do about slavery, and the colored race, I do because I believe it helps to save the Union; and what I forbear, I forbear because I do not believe it would help to save the Union. — [Washington, August 22, 1862, Abraham Lincoln in a letter to Horace Greeley]