from Fateful Lightning, A New History of the Civil War and Reconstruction, by Allen C. Guelzo, which is in turn a paraphrase of Allan Nevins:
Dominated by "stereotypes of each other, Northerners and Southerners were possesed by "fear," and "fear was largely the product of ignorance, and ignorance--or misinformation--largely the product of propaganda."
It was amazing to me, as I read through Chapter 2, which covered the political maneuvering between the North and South, and the negotiations and manipulations around slavery, how much has NOT changed.