I dont think the civil war can be said to only have one major cause. If I remember correctly, another major reason that the south seceded is because Lincoln was a protectionist president and the south was a very import/export focused economy. A tarrif war would not only wreck the southern economy but it would ensure that the south was paying the vast majority of taxes despite it's smaller population. I read somewhere that prior to the civil war, 60% of all federal taxes were paid by southerners while the south only accounted for 40% of the total population.
Lincoln's overarching agenda was to grow the size and authority of the US federal government and use it to modernize the country through investments in railroads and banking. He didn't seem to particularly like black people but thought that slavery was an irrational economic system which had no place in the future he was building. He also saw southern autonomy as an obstacle to modernization.
What is often left out of discussions about the Civil War is the lead-up to it. Battles were being fought before secession was declared, and they were over
slavery. The Kansas-Nebraska Act of 1854 repealed the Missouri Compromise which had restricted the spread of
slavery only to those territories south of a certain latitude. This lead to what is now called Bloody Kansas, a series of armed conflicts all throughout the Kansas and Nebraska territories between settlers on either side of the
slavery divide. The Republican Party was founded at the beginning of Bloody-Kansas as an explicitly anti-
slavery party. The first Republican meeting was held in 1854 in a schoolhouse in Ripon, Wisconsin attended by various stripes of abolitionist who wanted to organize against the spread of
slavery in the new midwestern states.
So yes, the Civil War was about slavery. It was about other things that involved slavery as well, like federalism and regionalism, but slavery was the way of life in the south and they went to war to protect it. In a sense, southern elites felt backed into a corner. Even if Lincoln would have left them be, they knew that the Republicans would block its spread and eventually slave states would be politically marginalized.
This history lesson has been free of value judgements thus far, just the facts. Now I editorialize a little:
Slavery was obviously outmoded, Lincoln was probably right about the need to modernize the USA, but I will not celebrate and glorify the rape of the south that accompanied it. Neither did Lincoln, given his reconciliatory posture post-war. Having visited some of the battlefields myself, I believe I have felt some of the gravity that doubtlessly weighed on his mind as he too pondered our unfortunate Brothers' War.
