Southern states began to secede from the union soon after Lincoln's election. The leaders of the South were convinced that Lincoln and his new Republican party would try to abolish slavery - even though Lincoln had said repeatedly that he just wanted to limit the further spread of slavery. To Southern leaders, limiting the spread of slavery spelled doom since they would eventually be outvoted in Congress.
It was the secession of states that brought about the war. The North fought to keep the Union of states together. The South wanted independence to maintain their state's rights - which was essentially the right to keep four million African American people in slavery.
You will get very angry answers from some Southern people that the war was not about slavery. I am a Southerner. I took a grad school history class covering the causes of the Civil War last year at a Southern university. All current academic thinking is that the issue causing the war was slavery. If you want to say it was states' rights - OK - it was the states' right to keep slavery. Slavery in the modern world is simply indefensible morally. You can't buy and sell people, break up families, own people as livestock.
