The book is scheduled to be released in the UK on 10 January, though some extracts have already been made public after it accidentally went on sale in Spain last week.
Harry's ITV interview contains more details of the brothers' fractured relationship - and Yahoo UK has broken down the key things Harry said about what he describes as his "sibling rivalry" with William.
Asked about the alleged physical confrontation, Harry says he and William "used to fight all the time" with BB guns and fireworks. But he said this time it was different, adding: "What was different here was this level of frustration and... I saw this red mist in him." Harry thought if he "wasn’t doing therapy sessions [and] being able to process that anger and frustration that I would’ve fought back, 100%".
Harry reveals that his mother's funeral plans initially meant only William would walk in the procession behind Diana's coffin because, at 15, perhaps he seemed old enough to handle it. However, Harry said "there was absolutely no way" he could let his brother do that by himself, and agreed to take part, something he said William would have done for him too.
Harry says William didn't like it when Diana dressed them in the same clothes when they were children, though he "found it quite funny".
Harry says he and William "felt guilt" when meeting with members of the public after their mother's death, and they didn't understand why when shaking hands, "wet hands that we were shaking, we couldn’t understand why their hands were wet. But it was all the tears that they were wiping away. So that was very strange for us, as, you know, youngsters".
Harry admitted he and his brother "shared a joke" as they walked behind their grandmother's coffin during her funeral procession earlier this year, saying: "Well, at least we know the way."
Harry spoke about how much he loves his brother and father and isn't trying to "harm" or hurt them by writing his memoir. But he wants his family and their staff members to admit they have been complicit in the negative press coverage of the Sussexes.
Harry insisted he wants to reconcile with his family and get his "brother back", but no longer recognises them, adding: "As much as they probably don't recognise me."
Harry claims his brother wasn't interested in spending time with him when he started at Eton College. The duke says in the interview that he was "hurt at the time", but now he has his own children, he realises siblings "need their space".
Harry claims he and William never wanted Charles to marry Camilla and asked him not to, but appreciated they "were and remain very happy together".
Harry says William "aired concerns" about Harry's plans to marry Meghan but never tried to "dissuade him" from doing it. He questions whether William's concerns about Meghan were based on that "maybe [William] predicted very early on what the press' reaction was going to be".
In one of his more controversial claims, Harry says William and Kate never get on with Meghan from the start. He says he thought having a wife or long-time partner would bring him closer to William and Kate. Instead, he claims that there was "stereotyping" that caused a "bit of a barrier to them really sort of, you know, introducing or welcoming her in". Asked by Bradby to explain, Harry says: "Well, American actress, divorced, biracial, there’s – there’s all different parts to that."
Harry talks about a “level of competition” with his brother. Discussing an argument about whether he should keep his beard for his wedding to Meghan, he says William “found it hard” that Harry could get to keep his beard while William had been previously told he had to shave his own one off.
Harry claims an unsuccessful attempt at reconciliation took place after his 2018 wedding, which ended in an awkward hug and Kate "gripping the chair" until her hands went white. Harry says he "had put a lot of hope in the idea that it would be William and Kate, and me and whoever. I thought the four of us would bring me and William closer together".
Harry explains that being "the third wheel to them [Kate and William], which was fun at times" but was "also I guess slightly awkward".
Harry describes an apparent exchange at Prince Philip's funeral in which William insisted that he just wanted his brother to be happy, and swore "on mummy's life", which Harry says was a "secret code" that was rarely used - adding that he "didn't believe him" anyway
Harry says he doesn't think William, or his dad, will read the book, adding: "I really hope they do, but I don't think they will".
Harry appears to claim that aides working for his father and stepmother used the press to brief against his brother. He says William and Kate went through “the same things Meghan and I went through” from Charles and Camilla’s office. He says ”William and Kate suffered” from the moment they were married. He goes on to say that he didn’t think the same would happen to him and Meghan, before adding: How wrong I was."
Harry explains that he and William have been set "on different paths", since their mother's death and that they are "two individuals who experienced a very similar traumatic experience but dealt with it in two very different ways".
He says he and William have discussed for "many years" who is "policing" the British press, but Charles called it a "suicide mission" trying to change things.