A short summary of my views: The casus belli was the secession of the southern states. The reason for the secession were the doom-spelling election results (Republican majority and a Republican potus), which were the pivotal point in the struggle of northern politicians to outlaw slavery. The main driving point behind that struggle was not the humanistic desire to emancipate the slaves, although it was actively used in propaganda. The main driving point was the desire to curb the economic and political power of the southern states. If the economic and political power of the southern states had been allowed to grow unchecked, the northern elite would've lost their power, the USA would've remained a primarily agrarian country and would've lagged behind the UK and Germany in the industrial race. In my opinion, calling slavery the reason for your civil war is a simplistic approach that's good for primary school ("And then, children, good president Lincoln told the Southern states he had enough of their evil ways and made them free their poor downtrodden black slaves. When they refused, he had to wage war on them, but in the end, white and black people held hands and were happy. Yes, Milly, you had a question? Why did it take another hundred years for black people to become full-fledged citizens? Um... Uh, because Mr. Lincoln was shot and no one else knew what to do!")