Megyn Kelly became a figure of great controversy during the 2016 campaign.

She attacked Trump personally during the first Republican Presidential debate and kicked off a long running feud with the future President.

But that was not her biggest act of betrayal.

Megyn Kelly also helped take down Fox News President Roger Ailes.

It was her testimony that helped push him out the door when Ailes’ workplace conduct was investigated.

Now a new book reveals Steve Bannon – then the chairman of Breitbart news – tried to warn Ailes that Kelly was a snake in the grass.

After Kelly tried to smear Trump in the first debate, Breitbart began reporting on Kelly’s anti-Trump agenda.

This caused Kelly to whine to Ailes about Breitbart’s coverage.

Ailes pushed back against the site – Kelly was Fox’s star anchor at the time – and took his complaints straight to Bannon.

The two could not come to a resolution and did not speak for one year.

Breitbart reports:

“In Chapter 8, Green writes about how the GOP base had a vehemently anti-Fox News reaction to Kelly’s performance in that Cleveland debate, in which she badgered Trump with over-the-top questions. Green writes:

Bannon and the Breitbart editors had the same reaction and immediately turned on Megyn Kelly, with a fusillade of negative articles. She became the newest Breitbart narrative: the back-stabbing, self-promoting betrayer-of-the-cause. And Breitbart became the locus of pro-Trump, anti-Fox conservative anger. Between Thursday night, when the debate took place, and Sunday evening, Breitbart published twenty-five stories on Kelly, and the site’s editor in chief, Alex Marlow, went on CNN to accuse Fox News of ‘trying to take out Donald Trump’ and staging ‘a gotcha debate.’

After a number of pieces from Breitbart News exposing Kelly’s agenda—including a lengthy one that exposed her lack of objectivity and open point of view being anti-Trump—Kelly was “furious” and begged then Fox News chairman and CEO Roger Ailes to intervene. Ailes has since passed away, but before he did he stepped down as chairman and CEO of Fox News. Bannon and Ailes—who were previously very close—did not speak again for “almost a year” after Ailes begged Bannon unsuccessfully on Kelly’s behalf to hold back Breitbart News criticisms of her transgressions against journalistic integrity.”

Bannon and Breitbart refused to back down.

Breitbart continued to aggressively cover Kelly’s biased coverage of Trump.

But before Bannon and Ailes ended their conversation, Bannon warned Ailes that Kelly would stab him in the back.

Breitbart also reports:

“In another excerpt from the book, Green writes:

In fact, its attacks on Kelly were growing more personal. ‘Flashback: Megyn Kelly Discusses Her Husband’s Penis and Her Breasts on Howard Stern,’ read a Breitbart headline on the one-week anniversary of the debate. Not knowing what else to do, Ailes dispatched his personal lawyer, Peter Johnson, Jr., to the Breitbart Embassy in Washington, D.C., to deliver a personal message to Bannon to end the war on Kelly. Bannon loathed Johnson, whom he referred to privately as ‘that nebbishy, goofball lawyer on Fox & Friends’—Johnson had leveraged his proximity to Ailes to become a Fox News pundit. When he arrived at the Embassy, Johnson got straight to the point: if Bannon didn’t stop immediately, he would never again appear on Fox News. ‘You’ve got a very strong relationship with Roger,’ Johnson warned. ‘You’ve gotta stop these attacks on Megyn. She’s the star. And if you don’t stop, there are going to be consequences.’ Bannon was incensed at the threat. ‘She’s pure evil,’ he told Johnson. ‘And she will turn on him one day. We’re going full-bore. We’re not going to stop. I’m gonna unchain the dogs.’ The conversation was brief and unpleasant, and it ended with a cinematic flourish. ‘I want you to go back to New York and quote me to Roger,’ Bannon said. ‘Go #$%^ yourself.’

Bannon’s warning came true when Kelly became the star witness against Ailes and Fox executives used her testimony to push him out the door.