All the wars including the civil war the US are involved in are about money. To get the public to accept them they have to appear to have a righteous cause. Usually bringing democracy to people that did not ask for it,In the case of the civil war it was freeing the slaves. The proof of this is in the treatment of freed slaves. The US is very good at getting poor men to fight for the rich man's money, goes right back to the war of independence.