I remember trying to formulate this question as a child in history class. I was roundly smacked back. The war was good. The war was against slavery. But the book stated that Lincoln only banned slavery in the states that succeeded. How then was this a war against slavery?
I was forced to rationalize it that Fort Sumter had been fired on and that was an act of war. However, from other reading it seemed that the South was angry and the voters wanted a war. The same was true half a century later when World War 1 broke out. It seems impossible now, but the populace broadly supported and wanted to go to war.
There is an interesting book on this subject with regards to VA. The younger men in VA felt their state was losing influence among others, that the heroes of the Revolution were in the past and that this influence, pride and glory needed to be refreshed. They thought they could make names for themselves as had the heroes of the past. The older men who remembered the Revolution and The War of 1812 were not eager to revisit those hardships. The older men had misgivings and tried to influence their sons and grandsons, but failed completely when Lincoln called for troops. I will have to look in my bookcase for the title and author and post it later.