Some things just don't die. but here goes my two cents.
The civil war was NOT about slavery. It was about State's Rights. And no, it wasn't the right to oppress people either. When you start talking like that you become a demagogue, just stirring up passions and completely ignoring the facts.
The South was an agrarian economy while the North was industrialist. The issue that caused the South to secede from the Union was the North's increasingly harsh infringements upon the South's economy. Up to this point, slavery was not an issue.
The South determined that the best course of action for it was to break away from the US. Now, consider for a moment that when the colonies seceded from England, they said it was not only their right, but their 'God given duty' to do so. The form of government in England caused to much suppression of freedoms in their land, so they said, "up your's" and started their own government. You would think that a country that originated in that manner would understand when a member state decided it could do better on it's own. But no.
When South Carolina seceded from the Union and the other Southern states followed suit and formed the Confederacy, they viewed this as a legal implementation of Article I, Section 10 of the Constitution wherin is stated:
No state shall, without the consent of Congress,
... enter into any agreement or compact with
another state... unless actually invaded, or in
such imminent danger as will not admit of delay.
The South's very livelyhood and method of production, slaves or no slaves, was in danger from the North. They did not believe that these dangers would, or could, be addressed in the congress. They were being forced to pay a tariff imposed by the federal government to help subsidize the Northern industrialists. In 1858, the South was paying 87% of the tariff revenue.
Furthermore, they Confederacy did not commit a treasonous act.
In Article III, Section 3:
Treason against the United States, shall consist
only in levying war against them...
In 1860, Abraham Lincoln promised not to interfere with slavery, but to "collect the duties and imposts". When Ft. Sumter was reinforced by Northern troops to impose these taxes, the South made a preemptive strike against what would have cost them their livelihoods.
Even before the war, Lincoln had promised to leave slavery intact, to enforce the fugitive slaves laws, and to support an amendment that would forever guarantee slavery where it then existed.
The issue of slavery was invoked by the North as a moral pretext for the war. It was designed to ignite the passions of the masses. Do you really think the Northerner's would have died to get some taxes for the already prosperous industries?
Karl Marx was quoted as saying, "the war between the North and the South is a tariff war. The war is further, not for any principle, does not touch the question of slavery, and in fact turns on the Northern lust for sovereignty."
This war was also the event which changed our nation from a loosely tied federalist central government into the invasive, bureaucracy we have today that invades our everyday lives with questionable legal precedents like the Roe v. Wade case.
Looking back to the issue of slavery. When Abraham Lincoln issued The Emancipation Proclamation it freed those slaves held "within any State or designated part of a State the people whereof shall then be in rebellion against the United States." It didn't apply to slaves in West Virginia and areas and states not in rebellion.
Slavery was not abolished in the Northern states until the 13th Amendment a full two years later.
After the Civil War came a period of punishment by the North. They destroyed the entire economic base for the Southern States and caused years of damage. If the North had truly been interested in the abolition of slavery and the equality of blacks and whites, they would have helped the slaves by striving to provide a better economy where they could prosper. Instead they inflicted another form of slavery upon them, as most of the newly freed slaves had no skills in demand and the economy in the South was to poor to provide jobs anyway.
one last note... this conflict is incorrectly referred to as the civil war. A civil war is a conflict between two factions of a nation seeking to gain control of that nation. To call this conflict the American Civil War is as correct as calling the American Revolution the English Civil War. It is more correctly referred to as "The War of State's Rights", "The War Between the States", "The War for Southern Independence", or "The War of Northern Aggression". Personally I'm kinda fond of that last one ;-)