Prince Harry served 10 years in the British Armed Forces, and the decision to leave is said to have left him struggling to cope with civilian life.
According to the new biography Finding Freedom, by royal reporters Carolyn Durrand and Omid Scobie, Harry struggled with his new life after choosing to leave the army. So much so that he even had panic attacks when attending royal events.
The book claims that when Harry took the "tough decision" to re-enter the royal family and duties, he couldn't cope with the media spotlight that he had long been away from.
The book stated: "Anger and anxiety started to bubble to the surface, and neither emotion fit into the official persona of a prince.
"At royal engagements, he suffered panic attacks. In the most proper and officious of settings, such as a reception by MapAction to mark Harry's new patronage of the humanitarian emergency response charity, the flight-or-fight instincts of an Apache helicopter pilot kicked in.
"A source remembers that when Harry left the event held at the Royal Society in London, he just started taking in deep breaths.
"The people, the cameras, the attention, he had just let it get to him. He was on the edge."
During his time of need, it was big brother William who was his rock, including one incident which saw Harry "fall into a bush".
"One night in early 2016, they both got 'totally drunk', according to the source. But it wasn't until Harry went outside to smoke that there was a problem.
"'He fell into a little bush. Someone tried to take a photo of him on their phone and Harry's protection officer literally jumped to block them from taking it,' the source said.
"'Harry was none the wiser. He just went back into William, so they could carry on drinking'."
In recent years, Harry and William are said to have had a falling out, which Durrand and Scobie claim occurred after William referred to Meghan as "this girl", before Harry married her.