A new biography from historian Robert Lacey will reportedly have the real details of the feud between Prince Harry and Prince William. Lacey's new book, Battle of Brothers: William, Harry and the Inside Story of a Family in Tumult, will expound on the Sandringham summit, where Harry met with William, the Queen and Prince Charles to discuss the Sussex couple's royal exit.

The Sandringham summit took place in January 2020, following Harry and Meghan Markle's bombshell announcement that they are stepping back from their royal duties. The book will apparently detail what went on in that meeting, especially between the royal brothers. 

Tatler reported that Lacey's biography contains high-level insider details that were never revealed to the public. Apparently, events surrounding the Sandringham summit was such a tensed moment because Harry had a confrontation with some of the palace staff when they refused his request for a meeting with Queen Elizabeth. 

Lacey's book, which is due in stores on Oct. 15, will also expound on the shocking feud between William and Harry prior to the latter's royal exit. The biographer said that the relationship of these royal brothers disintegrated long before Meghan Markle became a member of the royal family.

The divorce of Prince Charles and Princess Diana had an impact on the brothers' closeness as "seeds of damage were sown" even then. Lacey said that William and Harry have been acting out issues that go back to their childhood, leading the biographer to conclude that "nothing is more profound" than the heir and the spare conflict between the Dukes of Cambridge and Sussex. 

Lacey admitted that writing this book about the brothers was "painful and enthralling" as he deduced the state of their relationship. The author said that his book is a "devastating breakdown" of a brotherly bond that used to be solid and strong. 

Meawhile, amid the explosive book's release, royal correspondent Katie Nicholl said via Entertainment Tonight that William and Harry's relationship is so much better these days than six months ago. The Duke of Cambridge is talking with the Duke of Sussex over the phone more often than ever.

Nicholl, however, said that their relationship is still not at a level where they are comfortable to spend Christmas in one roof. But, things have definitely improved compared to when Harry and Meghan left for the U.S. Sources said that the brothers have been reaching out to each other since Prince Charles' coronavirus diagnosis in March.