What were the main causes of the U.S. Civil War?

This is not a popular opinion but I don't beleive that the war was about freeing the slaves. I have seen articles that suggest the real causes were France and England who wanted the U.S. to become divided and fail. I also have read that bankers promoted the war for their gain by pushing for the blockade that finally caused the South to confederate. If anyone has a verifiable reference to historical doents that define the issue I would appreciate hearing about it. Thanks.