In a new Fox Nation interview, former Defense Secretary James Mattis went into detail explaining his new book's praise for the leadership of President George H.W. Bush and its' stark criticism of the administration of the former president's son, George W. Bush.

On "Uncommon Knowledge with Peter Robinson", the former Marine Corps General and 26th Secretary of Defense addressed a passage in the book "Call Sign Chaos," where he applauded Bush 41's handling of the First Gulf War and described him as a strategically-competent president. 

"President George H.W. Bush knew how to end a war on our terms.  When he said we would take action, we did... He avoided sophomoric decisions like imposing a ceiling on the number of troops or setting a date when we would stop fighting," wrote Mattis according to excerpts of the book.

MATTIS SLAMS OBAMA, BIDEN FOR IGNORING REALITIES IN IRAQ

Mattis said that Bush 41's strengths as commander-in-chief were not necessarily related to his military service. "Take a look at one of the best president's that we ever had, President Lincoln.  He was quite fond of saying that the only military experience that he had was fighting mosquitos when he was called up for an indian war.  I think it has to do with the degree of humility, the degree of study of history, and the degree of team building and the willingness to listen to people that may have good ideas," said Mattis.

Strikingly, Mattis did not offer the same approval for the Bush 43 White House.

Specifically, Mattis wrote about the administration's decision to invade the Iraqi city of Fallujah in 2004.  The assault of Fallujah marked one of the bloodiest episodes of the entire Iraq War.  As the leader of the Marine Corps troops, Mattis wrote that he advised against a full attack on the city of up to 350,000 people, but he was overruled.

At that point, Mattis said that he expected the administration to be fully committed to the operation. "I made one strong statement up the chain of command: once we assault: don't stop us." Now reflecting on the Fallujah campaign, Mattis wrote, "You don't order your men to risk death and then go wobbly."

"That's as close as you come in this book to a real display of anger," said Robinson.

"It's frustrating because at this time the news media was full of -- unfortunately -- false reporting... there was a fair amount of political uproar over this talking about innocent people being killed... but the bottom line is -- deep inside the city -- we were ordered to halt," said Mattis.

On May 1, 2004, U.S. forces were ordered out of Fallujah, only to be told to return again.

Mattis concluded, "In this case, I believe it was a mistake, and that was proven because some months after I left command, of course, the Marines, the soldiers, the sailors, had to go back into Fallujah and we lost hundreds more -- killed and wounded because the enemy now had time to restore their ammunition stocks, build bunkers inside homes and it was a very, very tough fight."

WATCH: MATTIS SAYS HE DIDN'T HAVE 'TENSE' RELATIONSHIP WITH TRUMP

In the book, Mattis also faults Barack Obama and Joe Biden for poor leadership, and suggests their ignorance of reality contributed to the rise of ISIS in Iraq, according to excerpts reviewed by The Washington Examiner.

The book does not delve into Mattis' discussions with President Trump. Mattis, speaking to "Fox & Friends" on Tuesday, said only that he did not have a "tense" relationship with the president.

"I try not to talk, having parted ways with the administration over matters of policy," Mattis said. "I don't want to talk from the cheap seats now and make their job more difficult."

Mattis resigned from the Trump administration last December after clashing with the president over the withdrawal of U.S. troops from Syria and after two years of deep disagreements over America's role in the world.

To see the full interview on "Uncommon Knowledge with Peter Robinson", visit Fox Nation and join today.

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