None of these historical issues, moments, and people should be censored or else how do we study and know about them.
But for the South in the Civil War, two major (and many more minor) things were going on. 1st._ Yes, there were those who wanted to perpetuate slavery and resented the government trying to contain it. The fear of the spread of free states was more for fear of being outvoted in Congress than of there being fewer slave states. 2nd._ I believe any careful study of the War Between the States will reveal a strong regional philosophy that was (and still is) against a strong invasive central government. It is basically the Catholic view of 'subsidiarity' _ those know best who are closest to the situation (home rule). Thus the Catholic Church was the first and perhaps only foreign government to officially recognize the Confederate States of America. Southerners primarily fought for their state and region. The passion that Texans have for their state is not unlike the feeling most Tennesseans, Alabamians, Georgians and other Southerners feel for theirs.
This view is so central to my philosophy that _ though I almost enjoy being around minorities more than whites (I'm white); I have a brown Southeast Asian wife; I count black, Asian, and Hispanic men and women among my closest friends over the decades _ I am in favor of secession from the Union or strong autonomy for individual states within the Union [with basic nationwide rights maintained such as the right to bear arms or to worship and pray anywhere, anytime in America]. In other words, I'm not a racist, no where near it, but I would have fought for the Confederacy during the Civil War. Given the chance, though a loyal American now, given that chance in 1860, 10 times out of 10 I would have fought for the Confederate States of America. Then, after winning, I would have worked to abolish slavery throughout the South..
During the Civil War, even some blacks in the South defended these principles in battle without being forced to.
A footnote on slavery_ The slave traders in Africa who captured enslaved and sold the slaves to the shippers were almost exclusively Muslims. And there is Muslim slavery around the world today. Only modern social pressures from Western interests and countries probably keep some ordinary (non-radical) Muslims from practicing slavery more wide spread in our era, because they see non-Muslims as so far beneath them. Should Islam's current aggressiveness succeed, slavery will become more wide spread in a new Muslim dominated world.