Fox News host and bestselling author Bill O’Reilly joined Breitbart News Sunday and discussed his fifth book on American history, Killing Reagan: The Violent Assault that Changed the Presidency.

The cable news superstar preceded the writing of this book with his line of “killing” tales: Killing Lincoln, Killing Kennedy, Killing Jesus, and Killing Patton.

In his latest episode O’Reilly, a graduate of the Harvard Kennedy school of Government, teamed with Martin Dugard to tell the epic story of how the 40th president of the United States came within a whisper of losing his life just 69 days into his presidency. What most people don’t understand, O’Reilly explained, is the profound trauma that the bullets fired from the gun of attempted assassin John Hinckley had on the 70-year-old Reagan.

The miraculous thing about Reagan proved to be his effectiveness, despite the extreme physical hardship the President endured throughout his presidency as a result of the shooting. “He summoned the strength both physically and mentally not to overcome the wounds and the trauma, but to be effective despite of them. That is the real nobility. I had no idea Reagan had that kind of courage,” O’Reilly, a former high school history teacher, told Breitbart News Sunday listeners.

Most of the details of Reagan’s difficulties were shrouded in secrecy, O’Reilly contends, and “this attempted assassination changed the presidency, changed Reagan, and changed the country.” He argues that the suppression of Reagan’s real condition served the country well by not giving America’s detractors any advantage.

Breitbart News Executive Chairman Stephen K. Bannon, who hosts the program airing on SiriusXM Patriot radio cahnnel 125, complimented the purveyor of The Factor on Fox News, by saying that he though he knew much of what happened involving the harrowing incident, but that O’Reilly and Dugard came up with very original research and reporting. Bannon noted that the book is meticulously documented and void of anonymous sources.

One interesting side anecdote corroborated in Killing Reagan was that the Reagan campaign stole President Jimmy Carter’s debate notes and they knew everything Carter was going to say.

Mr. Bannon asked the author and newsman, who leads cable news shows for going on two decades, his thoughts on what has become known as the Cannon memo. The memo written by Reagan friend James Cannon, claimed that Reagan, because of the physical and mental stress he suffered from the Hinckley shooting, would be unable to complete his duties for a second term.

O’Reilly asserts that the memo is the “lynchpin” of Killing Reagan. If it was determined that he couldn’t complete his responsibilities as president “Reagan could have been removed from office under the constitution and they were very close to making that decision,” he pointed out. “But I don’t want to give up too much more because I want people to read the book.”

The most important aspect of all this, O’Reilly maintains is that “Reagan, some how, some way, Rises!” Bannon claims the Cannon memo is “breaking News. This assessment and analysis has never been done before. It’s never been dealt with like this and is certainly a central part of your book.”

Breitbart’s Executive Chairman asked O’Reilly, “Is something changing in the country? How powerful is the populist, nationalist, conservative, movement?” A movement that Bannon claims drives the rise of outsider Republican presidential hopefuls such as Donald Trump, Dr. Ben Carson, and Carly Fiorina.

The Fox News host answered, “something could change. But, I don’t think it is there yet.” O’Reilly explained that “there are still people who hang on to the legacy that America should not be the world’s super power. Our economy should not be free-market based. And there is a lot of those people.” He contends that many remain unconvinced that America became great by having a free market economy and fair competition. They don’t believe “that once America became great, America did great things such as defeating villains like Tojo, Hitler and Stalin.”

According to O’Reilly, there is a segment of the population that doesn’t appreciate the greatness of America and all the good it has done in the world. He agreed with Bannon that a large part of the problem in America is profound ignorance of the history of America.

“I think the populism thing we are seeing is a good thing,” O’Reilly acknowledged. He maintains that Trump, Carson, Fiorina, and others need to “up their game now.” If they can, he believes one of them can become the next president of the United States.