James McPherson seems to share an audience with Jeff Shaara (scroll down for Sharaa's comments). Here is Professor McPherson explaining the legal aspects of secession to his public:

They said, if you have a voluntary association of states you have no Union, if any state can pull out you have no country, you have no nation. As Lincoln said, this is the essence of anarchy. And so that was the political theory under which the North fought. It was the outcome of the war that decided the legitimacy or illegitimacy of these points of view.

You might thinks that a teen wrote that in a class paper after a late night on the town. Or that if you grade enough papers, you will start to think and speak like that. But Jeff Shaara understands.

Now, here, from the same interview, Dr. McPherson explains to his readers the dynamic behind Lincoln's Emancipation Proclamation:

Lincoln said over and over again before the war and during the war, that slavery is wrong, it's a monstrous injustice, it's a social, moral and political evil for the white man, to the Negro. He said, if slavery is not wrong, nothing is wrong, and so on. This was something that Lincoln believed was right, and when he issued the final proclamation on January 1, 1863, he said he did so because it was a military necessity, but also as an act of justice. And I think those two things, plus the foreign policy dimension, were all factors that he took into consideration.

Before reading Jeff Shaara's analysis, I would have thought these crude comments would embarass an undergraduate. Now I understand to whom McPherson is speaking and why he speaks and writes the way he does. Thanks, Jeff.