WASHINGTON — Former President Donald J. Trump told his top White House aide that he wished he had generals like the ones who had reported to Adolf Hitler, saying they were “totally loyal” to the leader of the Nazi regime, according to a forthcoming book about the 45th president.

“Why can’t you be like the German generals?” Mr. Trump told John Kelly, his chief of staff, preceding the question with an obscenity, according to an excerpt from “The Divider: Trump in the White House,” by Peter Baker and Susan Glasser, published online by The New Yorker on Monday morning. (Mr. Baker is the chief White House correspondent for The New York Times; Ms. Glasser is a staff writer for The New Yorker.)

The excerpt depicts Mr. Trump as deeply frustrated by his top military officials, whom he saw as insufficiently loyal or obedient to him. In the conversation with Mr. Kelly, which took place years before the attack on the Capitol on Jan. 6, 2021, the authors write, the chief of staff told Mr. Trump that Germany’s generals had “tried to kill Hitler three times and almost pulled it off.”

Mr. Trump was dismissive, according to the excerpt, apparently unaware of the World War II history that Mr. Kelly, a retired four-star general, knew all too well.

“‘No, no, no, they were totally loyal to him,’ the president replied,” according to the book’s authors. “In his version of history, the generals of the Third Reich had been completely subservient to Hitler; this was the model he wanted for his military. Kelly told Trump that there were no such American generals, but the president was determined to test the proposition.”

Much of the excerpt focuses on Gen. Mark A. Milley, who served as chairman of the Joint Chiefs of Staff, the country’s top military official, under Mr. Trump. When the president offered him the job, General Milley told him, “I’ll do whatever you ask me to do.” But he quickly soured on the president.

General Milley’s frustration with the president peaked on June 1, 2020, when Black Lives Matter protesters filled Lafayette Square, near the White House. Mr. Trump demanded to send in the military to clear the protesters, but General Milley and other top aides refused. In response, Mr. Trump shouted, “You are all losers!” according to the excerpt. “Turning to Milley, Trump said, ‘Can’t you just shoot them? Just shoot them in the legs or something?’” the authors write.

After the square was cleared by the National Guard and police, General Milley briefly joined the president and other aides in walking through the empty park so Mr. Trump could be photographed in front of a church on the other side. The authors said General Milley later considered his decision to join the president to be a “misjudgment that would haunt him forever, a ‘road-to-Damascus moment,’ as he would later put it.”

A week after that incident, General Milley wrote — but never delivered — a scathing resignation letter, accusing the president he served of politicizing the military, “ruining the international order,” failing to value diversity, and embracing the tyranny, dictatorship and extremism that members of the military had sworn to fight against.

“It is my belief that you were doing great and irreparable harm to my country,” the general wrote in the letter, which has not been revealed before and was published in its entirety by The New Yorker. General Milley wrote that Mr. Trump did not honor those who had fought against fascism and the Nazis during World War II.

“It’s now obvious to me that you don’t understand that world order,” General Milley wrote. “You don’t understand what the war was all about. In fact, you subscribe to many of the principles that we fought against. And I cannot be a party to that.”

Yet General Milley eventually decided to remain in office so he could ensure that the military could serve as a bulwark against an increasingly out-of-control president, according to the authors of the book.

“‘I’ll just fight him,’” General Milley told his staff, according to the New Yorker excerpt. “The challenge, as he saw it, was to stop Trump from doing any more damage, while also acting in a way that was consistent with his obligation to carry out the orders of his commander in chief. ‘If they want to court-martial me, or put me in prison, have at it.’”

In addition to the revelations about General Milley, the book excerpt reveals new details about Mr. Trump’s interactions with his top military and national security officials, and documents dramatic efforts by the former president’s most senior aides to prevent a domestic or international crisis in the weeks after Mr. Trump lost his re-election bid.

In the summer of 2017, the book excerpt reveals, Mr. Trump returned from viewing the Bastille Day parade in Paris and told Mr. Kelly that he wanted one of his own. But the president told Mr. Kelly: “Look, I don’t want any wounded guys in the parade. This doesn’t look good for me,” the authors write.

“Kelly could not believe what he was hearing,” the excerpt continues. “‘Those are the heroes,’ he told Trump. ‘In our society, there’s only one group of people who are more heroic than they are — and they are buried over in Arlington.’” Mr. Trump answered: “I don’t want them. It doesn’t look good for me,” according to the authors.

The excerpt underscores how many of the president’s senior aides have been trying to burnish their reputations in the wake of the Jan. 6 attack. Like General Milley, who largely refrained from criticizing Mr. Trump publicly, they are now eager to make their disagreements with him clear by cooperating with book authors and other journalists.

Secretary of State Mike Pompeo, who never publicly disputed Mr. Trump’s wild election claims and has rarely criticized him since, was privately dismissive of the assertions of fraud that Mr. Trump and his advisers embraced.

On the evening of Nov. 9, 2020, after the news media called the race for Joseph R. Biden Jr., Mr. Pompeo called General Milley and asked to see him, according to the excerpt. During a conversation at General Milley’s kitchen table, Mr. Pompeo was blunt about what he thought of the people around the president.

“‘The crazies have taken over,’” Mr. Pompeo told General Milley, according to the authors. Behind the scenes, they write, Mr. Pompeo had quickly accepted that the election was over and refused to promote overturning it.

“‘He was totally against it,’ a senior State Department official recalled. Pompeo cynically justified this jarring contrast between what he said in public and in private. ‘It was important for him to not get fired at the end, too, to be there to the bitter end,’ the senior official said,” according to the excerpt.

The authors detail what they call an “extraordinary arrangement” in the weeks after the election between Mr. Pompeo and General Milley to hold daily morning phone calls with Mark Meadows, the White House chief of staff, in an effort to make sure the president did not take dangerous actions.

“Pompeo and Milley soon took to calling them the ‘land the plane’ phone calls,” the authors write. “‘Our job is to land this plane safely and to do a peaceful transfer of power the 20th of January,’ Milley told his staff. ‘This is our obligation to this nation.’ There was a problem, however. ‘Both engines are out, the landing gear are stuck. We’re in an emergency situation.’”

The Jan. 6 hearings on Capitol Hill have revealed that a number of the former president’s top aides pushed back privately against Mr. Trump’s election denials, even as some declined to do so publicly. Several, including Pat A. Cipollone, the former White House counsel, testified that they had attempted — without success — to convince the president that there was no evidence of substantial fraud.

In the excerpt, the authors say that General Milley concluded that Mr. Cipollone was “a force for ‘trying to keep guardrails around the president.’” The general also believed that Mr. Pompeo was “genuinely trying to achieve a peaceful handover of power,” the authors write. But they write that General Milley was “never sure what to make of Meadows. Was the chief of staff trying to land the plane or to hijack it?”

Gen. Milley is not the only top official who considered resignation, the authors write, in response to the president’s actions.

The excerpt details private conversations among the president’s national security team as they discussed what to do in the event the president attempted to take actions they felt they could not abide. The authors report that General Milley consulted with Robert Gates, a former secretary of defense and former head of the C.I.A.

The advice from Mr. Gates was blunt, the authors write: “‘Keep the chiefs on board with you and make it clear to the White House that if you go, they all go, so that the White House knows this isn’t just about firing Mark Milley. This is about the entire Joint Chiefs of Staff quitting in response.’”

The excerpt makes clear that Mr. Trump did not always get the yes-men that he wanted. During one Oval Office exchange, Mr. Trump asked Gen. Paul Selva, an Air Force officer and the vice chairman of the Joint Chiefs of Staff, what he thought about the president’s desire for a military parade through the nation’s capital on the Fourth of July.

General Selva’s response, which has not been reported before, was blunt, and not what the president wanted to hear, according to the book’s authors.

“‘I didn’t grow up in the United States, I actually grew up in Portugal,’ General Selva said. “‘Portugal was a dictatorship — and parades were about showing the people who had the guns. And in this country, we don’t do that.’ He added, ‘It’s not who we are.’”