FAYETTEVILLE, N.C. — During his campaign, Donald Trump unabashedly revealed his obsession with historic generals whose personalities he perceives to have been strong, relentless and rough around the edges.

“George Patton was one of the roughest guys, he would talk rough to his men,” Trump noted as he praised Patton in February, lamenting that “[w]e don’t have that anymore.”

Trump also relayed an untrue story about Gen. John Pershing — a “rough guy,” according to Trump — allegedly executing Muslim insurgents with bullets that had been dipped in pig blood.

“We’ve got to start getting tough,” Trump said after sharing the myth.

During the second debate in October, he proclaimed, “Gen. George Patton, Gen. Douglas MacArthur are spinning in their grave at the stupidity of what we’re doing in the Middle East.”

Trump’s infatuation with the tough-guy personality also helps explain his praise of retired Gen. James Mattis, whom Trump has chosen to be secretary of defense.

Mattis earned the nickname “Mad Dog” because of his battlefield tenacity and propensity for bluntness, and after meeting with him during the selection process, Trump described him as a “true general’s general” and as “the real deal.”

Then, when announcing Mattis as his choice, Trump said he “is the closest thing to Gen. George Patton that we have.”

To be sure, Mattis’ appointment as secretary of defense might be cause for some concern.

Depending how many other former generals Trump chooses, there could be an imbalance in civil-military relations in the administration. And Mattis might not be particularly well suited for the bureaucratic, nonwarrior aspects of the job.

He should also be asked serious questions about his stances on Guantanamo detainees as well as the roles of women and LGBTQ people in the military.

But his personality, the respect he demands from Trump and the savvy leadership he demonstrated in his meeting with Trump could prove useful on many issues.

Mattis’ abrasive language may not resemble that of his predecessors in the post, but it’s the language Trump admires in a retired general, and America needs a secretary of defense who can pierce Trump’s shield of ego and stubbornness.

After all, Michèle Flournoy, who likely would have been secretary of defense under Hillary Clinton, said Mattis “would be an outstanding candidate” for the position, and that’s a meaningful endorsement.

Indeed, Trump may have found exactly the kind of warrior he loves, but Mattis’ selection is about more than that. Mattis’ personality, coupled with his reasonable policy views, is also precisely why America needs him as secretary of defense at this moment in our history.

For all his professed love for “tough guys,” Trump has displayed his scorn for military leadership (including claiming he knows more about ISIS) despite having no national security experience himself.

As such, it is critical to have a secretary of defense who not only commands Trump’s respect but whose responsible advice will also resonate with Trump and his advisers.

Mattis meets these criteria and most importantly has the audacity and cleverness to stand up to Trump effectively if need be.

This dynamic will be particularly important in relation to sensitive matters that Trump spotlighted during his campaign, such as waterboarding.

On this issue, Mattis has already forced Trump to reconsider the dangerous position he held during the race.

Although Trump indicated that Mattis has not necessarily changed his mind on the issue, he revealed how Mattis made a convincing case against waterboarding during their recent meeting: “He said — I was surprised — he said, ‘I’ve never found it to be useful.’ He said, ‘I’ve always found, give me a pack of cigarettes and a couple of beers and I do better with that than I do with torture.’ And I was very impressed by that answer.”

Mattis’ argument against waterboarding is an impressive example of how he would be a positive force in the Trump administration for several key reasons.

It shows that he can use simple reasoning and language to actually reach and influence Trump. Mattis’ underlying message was that the techniques authorized for U.S. interrogators, enumerated in an Army Field Manual, are sufficient, but he skillfully analogized those techniques using tough-guy terms — “a pack of cigarettes and a couple of beers” — that would appeal to Trump.

Mattis clearly understands which arguments will have an impact on Trump.

In addition to his love of tough talk, Trump’s business background means he likely best understands issues in transactional and utility-based terms, so instead of pitching moral or legal arguments against waterboarding, Mattis reached him by downplaying the practice’s usefulness and necessity.

This approach could prove useful not only on waterboarding, but also perhaps on Trump’s questionable campaign suggestion of targeting the families of terrorists.

Whether intentionally or unwittingly, it’s almost as if Mattis used an approach from the Field Manual to demonstrate, at least implicitly, the efficacy of its authorized techniques and the needlessness of “enhanced interrogation techniques.”

One of the techniques outlined in the Field Manual is the “Emotional Fear-Down Approach” where the interrogator “mitigates existing fear in exchange for cooperation.”

In a sense, Mattis was mitigating Trump’s exaggerated fear that terrorists will only respond to extreme measures and reassuring him that interrogators already have all they need to get the job done.

Trump’s apparent reassessment of his stance on waterboarding signifies the effectiveness of a harmless technique even on the man who would have us believe he’s the toughest of them all.

It’s possible Trump will ultimately resist Mattis on certain issues by, for example, trying to take advantage of a legal loophole by asking the Pentagon to add “enhanced interrogation techniques” to the Field Manual.

And while Mattis might be on an inevitable collision course, pitted against the irrational views of Michael Flynn and the rest of Trump’s coterie, he could be exactly the former Marine who America needs to stand guard in these battles.

If nothing else, Mattis’ forceful personality could serve as a significant bureaucratic roadblock and represent one of the few sources of hope and optimism in an otherwise disastrous administration.