Liberal invective against George W. Bush has not yet descended to the depths plumbed by conservatives in their crusade against the Clintons, but that isn’t because nobody’s trying. Mr. Bush’s most zealous opponents apparently believe that his faults, and those of his cronies and his administration, will be insufficient to unseat him next year. That may be why some Bush critics have been circulating a story about the financial connections between his paternal grandfather, Prescott Bush Sr., and a Nazi industrial magnate named Fritz Thyssen. The sinister cooperation between prominent American businessmen and their counterparts in Hitler’s Germany is an...