But Mattis as secretary of defense is no more a threat to civilian control than Dwight Eisenhower as president. Mattis understands that his role as a civilian secretary is different than his role as a general. He will respect the prerogatives of his generals and will expect them to respect his in turn. He will certainly not be overawed by flag officers.

I expect that Mattis would provide sound counsel to President Trump. He adheres to a more traditional view of American power than Trump—he supports NATO, cooperation with other allies, and forward presence and deployment. In addition, as someone who has seen war up close, he will not be inclined to use military force for frivolous reasons. He would pledge loyalty to the president but would expect loyalty in return. But his major contribution as secretary of defense may well be to rejuvenate the martial culture of the Pentagon after eight years of Obama’s social experimentation. I was present when he recently observed that the only reason to make changes to the U.S. military is to “make it more lethal,” suggesting that in his Pentagon, military effectiveness would once again trump “diversity” and political correctness.

He also would be a boon to healthy civil-military relations. It seems clear that American civil-military relations have been healthiest when there is a high level of trust between civilian and military leaders—that is, when there is mutual respect and understanding between them that leads to the exchange of candid views and perspectives between the two parties as part of the decision-making process.