This historian spent 10 years researching wartime presidents. Trump scares him the most.

“All wartime presidents have preserved our democracy largely through self-restraint, and I don’t see any of that in President Trump.”

That’s historian Michael Beschloss’s stunning observation. For his new book Presidents of War, he spent a decade looking at America’s wartime commanders in chief — how they handled the decision to send US troops into combat, how they navigated the politics surrounding war, and how the war changed them personally. 

I called up Beschloss to find out what he’s learned about the way America’s presidents go to war and what that tells us about how Trump might do it if a major fight breaks out.

What he told me was sobering. He said that every single one of America’s wartime presidents abused his power. “If you are worried about a president with authoritarian tendencies grabbing too much power, you look at a president in wartime,” Beschloss told me. “People will accept a lot of violations of their civil liberties in wartime.”

He also said that no president in American history scares him more than Donald Trump does. “He’s in a category of his own,” Beschloss told me during our interview, because Trump has shown no willingness to learn from history and little empathy — two key ingredients that make great wartime presidents who don’t eradicate most democratic norms. ...