Prince Harry was upset when he was forced to leave his front-line military duties in Afghanistan, according to a royal biographer.

Robert Lacey, a royal correspondent who appeared regularly on ABC's "Good Morning America" and author of "Battle of Brothers," shared how Prince Harry felt when he was forced to return just weeks after he was assigned to Afghanistan and how Prince William reacted to his younger brother's press conference.

Prince William and Prince Harry
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Prince William and Prince Harry attend the unveiling of a statue of their mother, Princess Diana at The Sunken Garden in Kensington Palace, London on July 1, 2021.

A report from Daily Mail recounted Lacey's story about the incident detailed in his 2020 book "Battle of Brothers." Just four weeks after he was deployed, Australian Magazine leaked the news, reportedly unaware of the "strict" blackout about the royal prince's presence in Afghanistan. American investigative site The Drudge Report picked up the report weeks later, and it made headlines, so Prince Harry was pulled out and was back to Britain shortly after.

Lacey spoke to Miguel Head, the Ministry of Defense official who had attempted to make Prince Harry's whereabouts a secret. Head later became chief of staff of the royal siblings.

Head told Lacey that Prince Harry was "very upset" and "very sad" that he couldn't continue his mission in Afghanistan. He was reportedly still wearing his combat gear covered in sand when he was flown back along with three seriously wounded men.

"He was very upset, actually,' recounted Head. 'He was really down. I wouldn't describe him as angry -- he's far more mature than that... He was just very sad about it,'" Lacey wrote.

Prince Harry, Prince William
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During Prince Harry's first press conference, only two or three questions were asked before his big brother, Prince William, reportedly decided to end it.

"Prince William suddenly stood up at the back of the room. He had been seated behind Head, and as the ministry man turned to look, he saw the older prince making a cutting motion with his hand across his throat -- saying, in effect, 'this is over,'" Lacey continued.

Prince William
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Britain's Prince William, Prince of Wales reacts as he visits the Millennium Powerhouse, a multi-service youth hub which works with a wide range of local organisations with a mission to create brighter futures for young people, in Moss Side neighbourhood on Nov. 16, 2023 in Manchester, England.

Head explained the Prince of Wales' reaction. It was reportedly down to how much he cared about his younger brother.

"It was simply a brother realizing that, at that point, nothing was more important than his brother's welfare...It says something about the closeness of the brothers and their authenticity as well," Head told Lacey. "They will not fake who they are simply to play a game or go along with other people's expectations."

Prince William and Prince Harry have reportedly been feuding since the latter stepped back from his royal duties. The beef worsened when the Duke of Sussex released his memoir, "Spare," in which he detailed his physical altercation with his brother over Meghan Markle.

Prince Harry, Prince William
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The heir was reportedly also not happy after the release of "Endgame" by Omid Scobie, a royal correspondent and biographer, dubbed the Sussexes' mouthpiece. The Dutch version of the book named his wife, Kate Middleton, and dad, King Charles, as the alleged two racist royals in the Palace.

Many believed it would take time before Prince William and Prince Harry could reconcile. Sarah Hewson, a royal editor at TalkTV, weighed in on the matter.

According to her, Prince William has "no plans" to see his younger brother. And the pair are only likely to reunite at the next family funeral.