Extreme One: The North fought a war against the South because they were acting out of altrusim and love for black people, and only wanted to bring it's wayward cousin, the Antebellum South, into civilization.
Extreme Two: The South was fighting a war against the North only to prevent excessive federalism, to promote states rights, and to preserve the right of secession.
The truth is that the South seceded and fought to preserve slavery. That was the entire reason it seceded without the fear that their slaves were going to be taken away there would have been no rebellion. The North fought to preserve the Union. Most did not give a shiite about slavery, blacks, the idiot culture of the South or any other excuse given for them fighting. Lincoln mobilized to put down the insurrection aimed at destroying the Union.
The truth is the South wanted nothing to do with Black soldiers and resisted to the end enlisting them in any significant numbers. This is easily shown by the records of hundreds of thousands of Blacks fighting for the North in constrast to the words quoted by Whiskey Papa showing the contempt the Southern leaders showed to the idea of black soldiers.
The proportion of blacks fighting for the Cornfederacy was as high as the proportion of Jews fighting for the Nazis. Either was an extreme anomaly.
The fact is most of the South was dirt poor, lacked education, did not own slaves, and were not in a position to know much more than what the local paper, delivered about once a month in some areas, said about the Fed over stepping it's bounds. Patriotism was more confined to the feelings for ones community or State than for a nation.
One either joined because his State, his family, and his neighbors were under attack than for any ideals or debate about slavery. Or in some cases the fighting man was conscripted.
Patriotism has always begun with community outward, ones family, town, state, country. Which ever comes under attack gleans the most patriotic fervor. For the common man, what was understood was that his area of the world was under threat, and I suspect that this was all that was needed to make many of them lock and load.