President-elect Donald Trump walks out with retired Marine Corps Gen. James Mattis after a meeting at the Trump National Golf Club in Bedminster Township, N.J. on Saturday. (Jabin Botsford/The Washington Post)

On the campaign trail he complained that they had been “reduced to rubble.” At other moments he suggested that he might have to fire them all.

Now that Donald Trump is president-elect, a parade of retired four-star generals has been making its way through Trump Tower and the mogul’s New Jersey golf course.

Trump’s sudden infatuation with the military’s top brass is part theater, part necessity and possibly a view into how he will govern. But it also raises a bigger question: What does Trump, whose military experience consists of military boarding school and multiple draft deferments, understand about the country’s general officer corps?

At least six former generals are being considered for as many as four top positions in a Trump administration — a concentration of military brass that foreign policy experts said is unprecedented in the recent history of the United States. In their ­charcoal-gray suits and short haircuts, they look like any other business executives. But these former officers, most of whom have spent their adult lives in the military and much of the past 15 years at war, are unlike the people Trump has encountered in corporate boardrooms. They are also unlike the politicians and political operatives who have dominated his life since he declared his intention to run for the White House more than a year ago.

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“He’s going to find them a strange and alien life form,” said retired Army Lt. Gen. David ­Barno, who commanded U.S. troops in Afghanistan. “They are motivated by different things. They have their own ethos that is different from business executives or entertainment people, and right now I think he’s entranced by that.”

The generals enjoy enormous public respect, and their plain-talking style and deep overseas experience could help add luster to Trump’s Cabinet. But the generals, if chosen for top jobs, could quickly feel put out by Trump’s sometimes-chaotic style, his tendency to repeat untruths and his controversial views on Islam, torture, U.S. treaty obligations and the laws of war.

When Trump talked about generals on the campaign trail, it was often to disparage them as political pawns of President Obama. “I know more about ISIS than the generals do, believe me,” Trump said last year, using an acronym for the Islamic State.

In other moments he has lavished them with over-the-top praise. “They’re so much braver than me,” he said at a rally last fall in North Carolina. “I wouldn’t have done what they did. I’m brave in other ways. I’m financially brave.”

The president-elect’s ideal of generalship frequently seems frozen in amber, harking back to his high school days at New York Military Academy. He regularly heralds the toughness of such World War II luminaries as Gen. George S. Patton and Gen. Douglas MacArthur, both of whom suffered major career setbacks for bucking authority.

Trump has praised the ruthlessness of Gen. John “Black Jack” Pershing, citing an apocryphal story in which Pershing is said to have ordered his men to dip 50 bullets in pigs’ blood and kill 49 Muslim terrorists in the Philippines during the early 1900s. One survivor was supposedly set loose to warn the others.

“For 25 years, there wasn’t a problem,” Trump said. “Okay? Twenty-five years, there wasn’t a problem.”

Retired U.S. Marine Corps General James Mattis is emerging as a potential favorite for President-elect Donald Trump's secretary of defense nominee. (Jenny Starrs/The Washington Post)

Trump’s favorite former general seems to be James “Mad Dog” Mattis, a retired Marine commander and a top contender for defense secretary whose hard-edge rhetoric in Iraq and Afghanistan has made him into something of an Internet meme. “Be polite, be professional, but have a plan to kill everybody you meet,” he famously told Marines in Iraq.

After their meeting in New Jersey this week, Trump tweeted that Mattis was “A true General’s General!” and “the real deal.”

Among Pentagon insiders Mattis is also known for his intensity, smarts and ability to build strong bonds with allies in the Middle East and Muslim world.

There are many reasons — both practical and political — that Trump finds generals so attractive. His focus on senior officers to fill out top foreign policy positions, such as director of national intelligence and secretary of defense, reflects the president-elect’s finely tuned understanding of the country and his base. “Trump loves generals so much because America loves the generals,” said Phil Carter, an Iraq veteran and senior fellow at the Center for a New American Security. “Even if he doesn’t pick any of them, just meeting with them in public reflects glory on Trump.”

Because the generals are not creatures of Washington, Trump sees them as fellow outsiders and kindred spirits. Most have spent their lives leading soldiers, sailors and Marines and can speak with a simplicity and directness that Trump appreciates and often seems to emulate.

And unlike a large percentage of the Republican Party foreign policy establishment, the vast majority of retired generals did not sign letters opposing his candidacy. “They aren’t part of the foreign policy swamp,” said Mark Cancian, a retired Marine colonel and senior adviser at the Center for Strategic and International Studies.

Despite the military’s appeal, Trump may be surprised by the generals on matters of style and policy. Some of the fiercest resistance to enhanced interrogation techniques, such as waterboarding, came from the military during the George W. Bush administration. Trump has said he backs such measures and admitted in an interview on Tuesday with the New York Times that he was taken aback when Mattis disagreed with him.

Trump’s campaign trail talk of temporarily banning Muslims or forcing them to register with the U.S. government is certain to draw resistance from most senior military officers, including those who have cycled through interviews with Trump in recent days. Although retired Army Lt. Gen. Michael Flynn, Trump’s pick for national security adviser, has described Islam as a threat to the United States, his views have alienated him from most generals and many of his former military mentors.

“I don’t think a single one of the generals, with the exception of Flynn, will buy into Trump’s view of the Islamic world,” Barno said. “All of them will reject the notion that Islam is the problem or that Muslims are the problem.”

Trump’s vision of ruthless battlefield commanders pursuing an implacable foe misses a lot about the modern general. The Iraq and Afghanistan wars have certainly involved a lot of fighting and killing, but generals have also spent an inordinate amount of time worrying about winning over civilians, wooing fickle tribal elders and managing sensitive allies.

They view alliances, such as NATO, as sacrosanct. Trump has said that the United States maynot defend NATO allies who do not “pay their bills.”

“War involves fighting, but so much more,” said retired Army Lt. Gen. James Dubik, who oversaw the training of Iraqi forces in Baghdad from 2007 to 2008.

The biggest difference between Trump and his generals could come in the realm of managing risk. Most generals spent decades methodically working their way through a massive bureaucracy with its own unique set of politics, customs and byzantine policies. They survived and in many cases thrived in a culture that rewards conformity over the brash, go-it-alone approach that has characterized Trump’s career.

“There are a lot of bold and bright colonels who never made general,” one former military officer said.

Trump’s unprecedented courtship of the brass also raises some troubling questions for a country built around civilian control of the military. For years, top U.S. officials have been pushing allies where the military dominates the highest levels of government, such as Egypt, Pakistan and Turkey, to cede more authority to civilians.

A general-heavy Trump administration could undermine that message. “This is a way that less-democratic governments conduct themselves,” said Kathleen Hicks, a senior official in the Obama administration and the Pentagon and an adviser to the Hillary Clinton campaign.

It also upends decades of tradition. “Civilian control is so fundamental to the character and the way we think about the United States,” said Jim Thomas, a former top official in the George W. Bush administration. “It’s something that should be preserved at all costs.”

The generals, though, may have the toughest adjustment when it comes to serving in a Trump administration. Most are accustomed to working through big staffs and often rigid chains of command, a stark contrast to the improvisational nature of Trump’s campaign and to how he seems to be putting together his Cabinet.

“Right now Trump is interviewing the generals, but they are also interviewing him,” Barno said. “They must be wondering, ‘Am I going to have to compromise my values and beliefs to work in this administration?’ That’s going to be a very tough question they all have to ask.”