Former Defense Secretary Jim Mattis contempt for his onetime boss Donald Trump is laid bare in a new book.

Mattis tried to stay away from the White House as much as possible during his time serving in the Trump administration, according to an excerpt from ABC News anchor George Stephanopoulos upcoming The Situation Room: The Inside Story of Presidents in Crisis .

Anybody with sense somebody like Mattis or [former Trump Secretary of State Rex] Tillerson they immediately shunned and stayed away from Trump, Stephanopoulos quoted former Trump Homeland Security adviser Tom Bossert as saying.

I mean, you couldnt get Mattis into the White House, Bossert added, per the book. His view was, Thats a madman in a circular room screaming. And the less time I spend in there, the more time I can just go about my business.

The Guardian shared an excerpt from the book last week.

Mattis, a retired four-star Marine general, served in the Trump administration from 2017 until the end of 2018. He resigned after disagreeing with Trumps decision to withdraw all American forces from Syria.

In 2020, Mattis broke his silence and shredded his former boss in an open letter to The Atlantic, saying Trump is the first president in my lifetime who does not try to unite the American people does not even pretend to try.

Instead he tries to divide us, he continued. We are witnessing the consequences of three years of this deliberate effort. We are witnessing the consequences of three years without mature leadership.