The "War of Northern Aggression" is still being fought. It is now fought in Courts, Congress and Bureaucracy with the continued growth of the Federal Government to the shrinking of states' and individual rights.
Slavery just happened to be the point of contention at the time.
Now, it is a variety of issues including control of education, control of business, control of speech, control of the right to bear arms, etc. The war was and is a battle of cultures.
The " Faith , Freedom and Responsibility " culture against the "Atheistic Big Brother" culture is where the battle lines are drawn today.