@M36:
Slavery was certainly a bone of contention between the North and South, but not one that could drive men to war. A million men do not take up arms and fight for 5 years over something they do not own. Same goes for the North.
Slavery was the symptom.
The issue was state rights versus federal rights.
Before the CW, states actually maintained armies and navies. States were sovereign entities that negotiated with each other through the Federal government. After the CW, states became subordinate to the dictates of the federal government and the military was federalized.
Today, federal law directly impacts areas of life that would have been unthinkable prior to the CW and states have lost a great deal of their authority in dealing with the problems and concerns of their local populations.
For example, federal laws are directly effecting the day to day curriculum taught to our children. That is so far beyond the initial scope of the Federal Constitution it is mind boggling.