Yeah, you'd have to research it more. Basically, many Southern states were threatening to secede, or block up Congress, or otherwise screw the country over ever since the 1800s. It was slavery, just in a roundabout way. What the slave-holding states were afraid of was the admission of new non-slave-holding territories as states, which would upset the balance of power in Congress and threaten their little social order. The North was afraid of admitting more slave-holding territories for the same reason. So for seventy years, they kept kicking the can down the road by only ever allowing as many new states as would maintain the even split in the Senate between free and slave states.
The 1850s finally fucked things up, when the Missouri Line agreement meant that any new slave states would have to squeeze in between Colorado and Mexico, and a bunch of Texans didn't want to pay American taxes, and there was a big fight over some taxation issues following a military venture into Central America, and... Well, what I'm trying to say is, the Southern states were willing to break the country if they couldn't have their way in Congress, especially in regards to maintaining slavery (which while never really on the table, no one ever accused Alabamans of rational strategy). And then that's exactly what happened. Does that condone, say, Grant burning the entire state of Georgia to the ground? Not really, no, but we're splitting hairs here.