In the upcoming book “Battle of Brothers: William and Harry,” royal historian Robert Lacey took a deep dive into the brother’s rumored rift and learned shocking things about the history of their relationship.

While some suspect that Prince William’s wife, Kate Middleton, and Prince Harry’s wife, Meghan Markle, caused the alleged rift, the author believes the monarchy and the brothers’ different personalities are to blame for the strain in their relationship.

“These two brothers – once so close as to seem inseparable and now separated by an ocean and by much more than mere distance – have been acting out the profound contradictions that go back into their childhoods and even before that: into their parents’ ill-fated,” he revealed.

“We have seen conflicts between heir and spare in every recent generation of the royal family – but nothing so profound as this.”

However, if William and Harry are going to truly repair their relationship, Lacey believes Queen Elizabeth is the key. The royal historian revealed the Queen “will quite surely play a crucial role.”

Although there have been reports suggesting Prince William and Prince Harry are in the process of working in their relationship, Lacey credit Queen Elizabeth for not allowing the royal family to look weak amid the fallout.

“This dispute between brothers ranks alongside the abdication of King Edward VIII in its impact upon the British monarchy and how it operates,” he explained.

“The Queen herself has handled the crisis superbly – you might not even guess there is a crisis at all from her calm and stoic manner! As for Princes William and Harry, the two main protagonists in the rift, they have also acted with honesty and decency within the system, as have their wives.”

Lacey’s book, which will also explore how much of an impact Kate and Meghan had on the brother’s rift, is expected to be released in October.

Prince Harry and Prince William
Prince Harry and Prince William are photographed. AFP/Tolga AKMEN