EagleandLiberty is right. The cause was (and still is) states rights. The occasion was slavery which turned out to be an albatross around the neck of states rights.
If Obama is elected, the occasion will be liberty itself.
No it wasn't. Not even in the slightest.
First, there is no such thing as "states' rights." States are governments and governments do not have rights - people do.
Second, even if states had any of these imaginary rights, the federal government had done absolutely nothing to violate these pretended rights in any way before the seceding states seceded.
The whole concept of "states' rights" is an invention cooked up to preserve slavery.
If it weren't, defenders of the Confederacy would be able to itemize these alleged offenses against "states' rights" - but they never can.