Donald Trump's former Defense Secretary Jim Mattis referred to his boss as a "madman in a circular room screaming" — and that was hardly the end of his disdain, according to an upcoming book.

The retired four-star Marine general lasted only a year after joining the Trump administration in 2017. He quit over Trump's decision to yank American forces out of Syria.

"You're going to have to get the next secretary of defense to lose to ISIS. I'm not going to do it," Mattis told the Atlantic he responded to Trump. "I had no choice but to leave."

Mattis' assessment of the former president as a screaming madman was bared by Tom Bossert, Trump's homeland security adviser, as recounted in the book "The Situation Room:The Inside Story of Presidents in Crisis by journalists George Stephanopolous and Lisa Dickey.

Bossert also pointed out that Trump hated to go to Situation Room military breifings because he thought generals should come to him, according to the book, which is due out next week.

"You couldn't get Mattis into the White House," Bossert reportedly told the authors in the book, a copy of which was obtained by the Guardian.

"Anybody with sense — somebody like Mattis or [former Secretary of State Rex] Tillerson — they immediately shunned and stayed away from Trump," he said.

The book also reveals that Trump ordered aides to create books of chyrons — basic descriptions of the news that appear at the bottom of TV newscasts — in order to simplify the stories of the day for him.

The authors called it "surely one of the most prosaic tasks ever required of the highly trained intelligence officers serving in the White House," the Guardian noted.

The book's latest on Mattis is part of his long-festering view of Trump.

He was quoted by Washington Post editor and Watergate journalist Bob Woodward in his 2020 book "Rage" as calling Trump "unfit" and "dangerous" because he has "no moral compass."

Mattis also complained in a 2020 letter to the Atlantic that Trump was the "first president in my lifetime who ... tries to divide us" and accused him of "making a mockery of the Constitution."

Trump was relieved when Mattis left his administration.

"I gave him a new life, things to do, and battles to win, but he seldom 'brought home the bacon,'" Trump wrote afterward on social media." I didn't like his 'leadership' style or much else about him, and many others agree. Glad he is gone!"