The War for Southern Indepence is so complex no one can pin point one specific cause. I think David said it best
One State seceded over slavery, five States seceded over the right to secede and seven States seceded because the Northern President attacked the other six. No one else has so correcetly simplified the cause of the War better than that.
OK, but the subject line was slavery being the cause of the WBS, and I think David just backed up what I was saying, South Carolina seceding was the start of the WBS, there would have been no war if no state had not seceded. So, thank you David, for backing me up!