Prince Harry Writes of Physical Attack by Brother William

“He knocked me to the floor,” Harry recounts of the alleged assault by Prince William, according to The Guardian, which said it had obtained a copy of Harry’s coming book.

Prince Harry accused his brother, Prince William, of knocking him to the floor during a furious argument over Harry’s marriage to Meghan Markle, according to a report on Thursday in The Guardian, which said that it had obtained a copy of the younger prince’s memoir nearly a week ahead of its publication date.

The physical assault, which is said to have taken place in Harry’s cottage on the grounds of Kensington Palace in 2019, is one of a string of revelations in the prince’s book, titled “Spare,” which is due out on Tuesday.

The book has been awaited with dread by the royal family and with anticipation by millions of others riveted by the long-running House of Windsor soap opera. In recent days, Harry has dribbled out unsavory details of his rift with William and with other family members to stoke interest.

“Willy, I can’t speak to you when you’re like this,” Harry said to his brother, handing him a glass of water, after William turned up at his cottage and railed that Meghan, an American-born actress, was “difficult, “rude,” and “abrasive,” according to the Guardian article.

“He set down the water, called me another name, then came at me,” Harry wrote, according to the report. “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.”

William urged Harry to hit him back, according to the account, but he refused. William then told Harry, “You don’t need to tell Meg about this.”

Harry replied, “You mean that you attacked me?”

“I didn’t attack you, Harold,” William insisted.

Harry wrote that his first telephone call after the altercation was to his therapist, the report added.

That the sons of King Charles III call each other Willy and Harold was a delectable morsel amid the apparently lavish banquet of disclosures in the book. The Guardian said that the memoir goes into anguished detail about the rift between the brothers, which deepened after Harry and Meghan withdrew from royal duties and moved to Southern California.

The publisher, Penguin Random House, has tried to keep the book under tight wraps, embargoing the contents and only shipping it to bookstores just before its scheduled release. But the Guardian said that it had obtained a copy nearly a week before the publication, effectively pre-empting a rollout that includes two television interviews with Harry next Sunday, with ITV in Britain and the CBS program “60 Minutes” in the United States.

Martin Pengelly, the New York-based Guardian reporter who wrote the story, has a history of breaking news about tightly guarded books, including some about former President Donald J. Trump, often several days ahead of their publication.

Mr. Pengelly did not provide an exhaustive account of the book in his article. But he reported that Harry recalled a tense meeting with William and Charles after the funeral of Prince Philip in 2021, during which his father pleaded, “Please, boys, don’t make my final years a misery.”

Representatives of King Charles and of Prince William declined to comment on the allegations on Thursday, which came on the heels of various other accusations by Harry and Meghan made in a six-part Netflix documentary that aired last month.

Buckingham Palace did not comment on Harry’s claims in the documentary that it refused to defend Meghan from an onslaught of negative coverage by the London tabloids — and in some cases, even fueled it with damaging leaks to reporters.

Despite his litany of grievances, Harry has insisted that he wants to reconcile with William and Charles. “I would like to get my father back; I would like to have my brother back,” he said in a clip from the interview with ITV. “They’ve shown absolutely no willingness to reconcile.”

On Tuesday, a person with ties to Buckingham Palace disputed that Harry had made any peace overture. The person requested anonymity to disclose private information about the family. The last time the brothers appeared together was after the death of Queen Elizabeth II in September, when they, along with their wives, went for a stilted public walkabout before her funeral.

Any rapprochement seems unlikely in the wake of the allegations in “Spare.” The book’s title is a play on the phrase “heir and spare,” referring to Harry’s diminished status as the younger brother in a monarchy where succession is governed by primogeniture.

Early in the book, the Guardian reports, Harry recalled hearing a story of how, when his mother, Diana, Princess of Wales, gave birth to him, a pleased Charles told her, “Wonderful! Now you’ve given me an heir and a spare — my work is done.” The article does not make clear how the story was relayed to Harry, or by whom.

The public disintegration of Harry’s relationship with his family has played out in a series of highly promoted set pieces. In March 2021, Harry and Meghan sat down with Oprah Winfrey for an interview in which Meghan, who is biracial, claimed that a member of the royal family had expressed concerns about the skin color of her unborn baby. The couple has never identified the family member; Ms. Winfrey said it had not been the queen or the queen’s husband, Philip.

Meghan also told Ms. Winfrey that she had been so isolated and emotionally desolate inside the palace that she once considered suicide.

The Guardian did not say in its report whether Harry’s book repeated the allegations about racism in the royal family. The couple did not allude to it in the Netflix documentary, and William said in 2021, “We’re very much not a racist family.”