The much-written about feud between Prince William and Prince Harry started decades ago, well before William married Kate Middleton and Harry married Meghan Markle.

Their split became visible when Harry and Meghan separated their home and office from William and Kate’s in 2019, but in Battle of Brothers, excerpted in People, historian Robert Lacey says their rift dates back to their parent’s troubled marriage. 

Their parents, Prince Charles and Princess Diana, famously divorced before her death in 1997. 

Lacey tells People: "Both brothers have been damaged by their upbringings; both have reacted by finding different solutions. There is so much pain and trauma in this story, going right back to the beginning."

Lacey says they "were raised to be close and protective of each other," but tensions developed later as William was prepped for his role as future monarch while Harry was left without a defined role of his own. Then, when Harry and Meghan got together, William warned him that he was moving too fast. 

"Fundamental to the whole saga is the clash of love versus duty," explains Lacey, adding that the brothers face "potential tragedy" if they can't come together again.

"This compares with Edward VIII’s abdication in 1936 and the death of Princess Diana in 1997," says Lacey. "It’s of that scale. And it's a challenge that’s yet to be resolved."