Originally Posted by crockett

You are confusing the secession and the war. Yes the confederate states withdrew from the Union, because their economies were at stake over slavery. However the North did not go to battle with the south over slavery.

The north fought the south in order to force the south back into the union and to control them. union troops would not of marched on the slave holding states over slavery had they not left the union. Slavery, would have continued on for a very long time if there was no break in the union at that time.