When Maggie Haberman and Jonathan Swan sat down with President Trump in the Oval Office earlier this year to interview him for their new book, Regime Change: Inside the Imperial Presidency of Donald Trump, he eagerly produced a two-page letter from a supporter he described as a historian. The letter’s premise was extraordinary: that Trump was more powerful than some of history’s most consequential figures, including Napoleon, Joseph Stalin, and Adolf Hitler.
The author of the letter was…

