In a leaked extract of his highly anticipated autobiography, Spare, to The Guardian newspaper, Prince Harry alleged the confrontation took place at his London home in 2019 and had left him with a visible injury to his back after the Prince of Wales grabbed his brother by the collar and ripped his necklace before knocking him to the floor.
Harry further claimed William had called the American actress “difficult”, “rude” and “abrasive” – comments which the younger brother said parroted “the press narrative” about his wife.
According to The Guardian newspaper, the “extraordinary scene” is “one of many in Spare” which is due to be published on January 10.
The newspaper said it was able to obtain a copy of the book despite “stringent pre-launch security around the book”.
Its article goes on to say that, according to Harry, his elder brother had wanted to discuss “the whole rolling catastrophe” of their relationship and struggles with the press.
But when William arrived at Nottingham Cottage – where Harry was then living – in the grounds of Kensington Palace, the Prince of Wales was already “piping hot”.
“After William complained about Meghan, Harry writes, Harry told him he was repeating the press narrative and that he expected better,” The Guardian reports.
“But William, Harry says, was not being rational, leading to the two men shouting over each other.
“Harry then accused his brother of acting like an heir, unable to understand why his younger brother was not content to be a spare.”
Insults were then exchanged between the two men, before William claimed he was trying to help, claims which Harry found incredulous, and informed his brother of such, angering William.
He writes: “(William) called me another name, then came at me. It all happened so fast. So very fast. He grabbed me by the collar, ripping my necklace, and he knocked me to the floor. I landed on the dog’s bowl, which cracked under my back, the pieces cutting into me. I lay there for a moment, dazed, then got to my feet and told him to get out.”
Harry writes that William urged him to hit back but he refused. Shortly afterwards though, the elder brother apologised.
William had then told his brother not to tell Meghan about the confrontation, resulting in Harry saying: “You mean that you attacked me?”, to which William responded: “I didn’t attack you, Harold.”
Harry said he did not immediately tell his wife but she had noticed “scrapes and bruises” on his back.
Earlier in the memoir, the duke reportedly elaborates on the story behind the book’s title, Spare. According to The Guardian, he recounts what the King said to Diana, Princess of Wales on the day of his birth.
His father, Harry claims, told the then-Princess of Wales: “Wonderful! Now you’ve given me an heir and a spare – my work is done.”
The duke’s extraordinary book claims come after the release of a teaser trailer from an ITV interview in which Harry said he wants his father and brother back.
The interview, due to be released on Sunday, will be broadcast two days before Spare is published around the world.
In a series of clips from the duke’s ITV conversation, Harry tells presenter Tom Bradby: “It never needed to be this way”, and refers to “the leaking and the planting” before adding: “I want a family, not an institution.”
He also says “they feel as though it is better to keep us somehow as the villains” and “have shown absolutely no willingness to reconcile”, although it is unclear who he is referring to.
Filmed in California where the duke now lives, ITV said Harry: The Interview will go into “unprecedented depth and detail” about his life in and outside the royal family.
Mr Bradby, a former royal correspondent and current presenter of ITV News at Ten, is a friend of the Sussexes and previously interviewed them for a documentary about their 2019 Africa tour.
But in a separate interview with CBS News, set to air the same day, Harry also criticises Buckingham Palace over an alleged failure to defend him and his wife, the Duchess of Sussex, before they stepped down as senior royals.
The duke also reveals to the US broadcaster that he would not return to the institution as a full-time royal.
Both CBS and ITV have released snippets of the duke’s conversations ahead of the full interviews being televised.
Speaking with CBS’s Anderson Cooper, Harry talks of the “betrayal” by Buckingham Palace, telling the 60 Minutes programme: “Every single time I’ve tried to do it privately, there have been briefings and leakings and planting of stories against me and my wife.
“The family motto is ‘never complain, never explain’, but it’s just a motto.
“They (Buckingham Palace) will feed or have a conversation with a correspondent, and that correspondent will literally be spoon-fed information and write the story, and at the bottom of it, they will say they have reached out to Buckingham Palace for comment.
“But the whole story is Buckingham Palace commenting.
“So when we’re being told for the last six years, ‘we can’t put a statement out to protect you’, but you do it for other members of the family, there becomes a point when silence is betrayal.”
It comes after the duke claimed in his Netflix documentary that William broke a promise to him never to leak stories or brief against one another after witnessing the fallout of such actions in their father’s office.