These allegations came to light via a leaked extract from the memoir to the Guardian newspaper, which claims that the brothers were arguing over the Duke of Sussex's marriage to Meghan Markle.
The article states that William had allegedly branded Meghan "difficult", "rude" and "abrasive". Such comments were simply parotting "the press narrative" about his wife, according to Prince Harry.
This alleged altercation took place at Harry's home in Nottingham Cottage at Kensington Gardens in 2019, and allegedly left Harry with a visible injury to his back, as he claimed that William had grabbed him by the collar, ripping off his necklace and knocking him to the ground.
According to Harry, his brother was already "piping hot" by the time he arrived at his home, where has keen to discuss "the whole rolling catastrophe" of Harry's marriage and their struggles with the press.
"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", the paper added. "Harry then accused his brother of acting like an heir, unable to understand why his younger brother was not content to be a spare".
Following an exchange of insults, Prince Harry allegedly dismissed William's claim that he was only trying to help.
It was at this point that an angry William swore at his brother, before stepping towards him, scaring Harry.
"(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.
According to Harry, Prince William later urged him to hit him back, which Harry refused to do. The Prince of Wales allegedly apologised for his actions, begging Harry not to tell his wife about this incident.
While he did not his inform his wife, Meghan Markle allegedly noticed "scrapes and bruises" on his back.
The Guardian has also claimed that this row is “one of many in Spare”, which will be released next week (January 10).
