It starts with Senator Jefferson Davis resigning from the Senate. If you are interested in a lengthy explanation for the causes for the war you won't find it in this trilogy, which is more about the war itself. I'm sure there are plenty of books that do cover it, though.

The South's quest for international recognition is well-documented, which really is about how Great Britain was disinclined to recognize a nation that came into existence almost solely as the result of its desire to hold slaves, and how France under Napoleon III would not act without Great Britain. Russia was pro-Union from the start.

Foote notes that Lincoln was a skillful politician and doesn't have any problems stating that he would break "any promise" if it suited him. He tries to portray Lincoln in his totality, rather than through a distorting lens of idealism (in fact, he avoids falling into the trap of the "noble cause" of the South, too). However, your comments about hero-worship seem to apply to a different America than the present one. In the post-Watergate Presidential myth-smashing and cynical America of the turn of the millennium, there is very little inclination to engage in hero-worship. If anything, Foote showed me in a far more mature way that the hero-worship had a sound basis in fact, and that in our haste to tear down idols we perhaps discount too much. While the book may have been written (mostly) before the cynical turn in America, it seemed to anticipate it and makes a stronger, more compelling argument for thinking people, rather than resort to base cliche.