I really don’t see what Buchanan said here that was wrong. He didn’t deny Hitler was an evil man. But he couldn’t have achieved what he did, if he didn’t have some brilliance to him.
And yes, he did make fools of the Statesmen who were in his path, and his Generals who didn’t think he should have even marched into The Rhineland.
Unless I read it wrong (the whole article) he is putting out a strong suggestion that the USA should have allowed Hitler to do what he wanted.