An interesting take on James McPherson and Civil War publishing:
"The guy's everywhere, like Viagra spam."
The author of this op-ed cleverly interprets McPherson's ubiquity as a highly public signal sent by event organizers, by publishers, by audiocassette manufacturers. The signal is "Nihil obstat," church Latin for "nothing objectionable" in this content.
McPherson's blurbs, therefore, are less a conventional "seal of approval" than a label assuring potential buyers that the material conforms to the Nevins/Catton/Williams interpretation of Civil War history.
And that, I think, is an extremely useful service rendered pop history's mass audiences. Of course, it helps the serious Civil War reader too, though not in the way intended.