In their book, The Divider: Trump in the White House, Peter Baker and Susan Glasser reported that Trump asked John Kelly, his chief of staff at the time, “Why can’t you be like the German generals?” Trump, at various points, had grown frustrated with military officials he deemed disloyal and disobedient. (Throughout the course of his presidency, Trump referred to flag officers as “my generals.”) According to Baker and Glasser, Kelly explained to Trump that German generals “tried to kill Hitler three times and almost pulled it off.” This correction did not move Trump to reconsider his view: “No, no, no, they were totally loyal to him,” the president responded.
This week, I asked Kelly about their exchange. He told me that when Trump raised the subject of “German generals,” Kelly responded by asking, “‘Do you mean Bismarck’s generals?’” He went on: “I mean, I knew he didn’t know who Bismarck was, or about the Franco-Prussian War. I said, ‘Do you mean the kaiser’s generals? Surely you can’t mean Hitler’s generals? And he said, ‘Yeah, yeah, Hitler’s generals.’ I explained to him that Rommel had to commit suicide after taking part in a plot against Hitler.” Kelly told me Trump was not acquainted with Rommel.
[...]
This wasn’t the only time Kelly felt compelled to instruct Trump on military history. In 2018, Trump asked Kelly to explain who “the good guys” were in World War I. Kelly responded by explaining a simple rule: Presidents should, as a matter of politics and policy, remember that the “good guys” in any given conflict are the countries allied with the United States.