Both Sean Spicer and Marine Le Pen have in recent days uttered claims that might well fit under the capacious tent of "Holocaust revisionism." Spicer has walked it back, and one can generously attribute his comments to gross maladroitness in the performance of ... well ... his job. Still: such events do give us the opportunity to observe that much of the crap that passes itself off these days as "Holocaust revisionism" traces itself back to Harry Elmer Barnes, a paid apologist and propagandist for Nazi Germany in real time. Barnes may have been atoning for his own war guilt. During the "Great War," 1914-18, Barnes was an enthusiast for the crusade against the Huns. When peace came, Barnes (like many at the time) wondered what it all had been about. He concluded not just that he had been overly enthusiastic, not just that he had been wrong in seeing the war as a matter of white hats versus black hats, but that in fact he had had the 'hats' t...