First it was Michael Flynn.

Then came James Mattis.

Now we hear that John Kelly is joining the Donald J. Trump administration. What do these men have in common?

They’re all retired generals. Flynn is a soldier; Mattis and Kelly are Marines. Among them they have 11 stars on their epaulets. Army Lt. Gen. Flynn will be the national security adviser; Marine Gen. Mattis will be defense secretary; Marine Gen. Kelly is slated to be nominated to lead the homeland security department.

Hey, didn’t Trump say he knows “more than the generals, believe me” about ISIS?

It might be that perhaps he’s rethinking that bold — and reckless — boast. If so, then he ought to acknowledge as much.

But here’s another fascinating aspect of these men: They’re all blunt talkers. They speak their mind. They are take-no-prisoners kinds of men when it comes to policy discussion and debate.

The Flynn-Mattis relationship might be particularly fascinating to watch, given the traditional tension that exists between the national security chief and the defense boss.

Moreover, will these men’s penchant for candor and frankness work well with a president known to be, um, less than receptive to other people’s points of view, let alone these so-called truth-tellers?

This could be dramatic in the extreme.