Speaking in his new Netflix docuseries, Heart of Invictus, the Duke of Sussex said returning from the tours brought up unresolved trauma from losing his mother, Princess Diana, at age 12 - but that these feelings were “never discussed”.
The Duke is fronting a new five-part Netflix series as part of a multi-million pound deal, which previously saw the Sussexes document their struggle with royal life in a six-part documentary series, Harry and Meghan.
Speaking in the new series, Harry said he finally sought therapy after a lack of support with his mental health on his returning from Afghanistan after “lying on the floor in the foetal position".
“I can only speak from my personal experience, my tour of Afghanistan in 2012, flying Apaches," he said in the series’ second episode.
“Somewhere after that, there was an unravelling.
“The trigger to me was actually returning from Afghanistan. But the stuff that was coming up was from the age of, from 1997, from the age of 12.
“Losing my mum at such a young age, the trauma that I had, I was never really aware of.
“It was never discussed. I didn't really talk about it and I suppressed it like most youngsters would have done, but then when it all came fizzing out, I was bouncing off the walls. I was like 'what is going on here? I'm now feeling everything as opposed to being numb'.
He added: “The biggest struggle for me was ... no-one around me really could help.
“I didn't have that support structure, that network or that expert advice to identify what was actually going on with me.
“Unfortunately, like most of us, the first time you really consider therapy is when you're lying on the floor in the foetal position, probably wishing that you'd dealt with some of the stuff previously, and that's what I really want to change.”
The documentary, which was launched in the UK at 8am on Wednesday, follows a group of service members on their road to the paralympic-style sporting competition which Harry set up in 2014 for injured and sick military personnel and veterans.
When asked what he does in the documentary, he replied: “What do I do? Er... on any given day, I'm a dad of two under-three-year-olds.
“I've got a couple of dogs. (I'm) a husband. I'm founding patron of Invictus Games Foundation.
"There's lots of hats that one wears, but I believe today is all about Invictus.”
Meghan, the Duchess of Sussex, first appears in behind-the-scenes footage from November 2021 when the couple attended the Salute to Freedom gala honouring military veterans in New York.
Harry confides in his wife about his nerves as they walk hand in hand along a red carpet into the event, saying: “We haven't done this in a while,” to which Meghan replies, “I know.”
Prince Harry is then shown anxiously pacing around a room as he waits to take to the stage, adding: “My heart ... I'm like [making a noise like a rapid heart beat] - I'm nervous.”
In the first 45-minute episode of the series, Army veteran Harry, who undertook two tours of Afghanistan, also discusses how he never wanted to serve in the Armed Forces as a father, saying: “It's never the individual signing up - it's the whole family signing up.”
The couple are under pressure for the new series, for which Harry was executive producer, to be a ratings success after the Sussexes’ lucrative media deal with Spotify ended in June after just one season of Meghan's podcast Archetypes.
During a special screening of Heart of Invictus in California, Harry emerged to introduce it, to the surprise of the audience.
In a video circulating on social media, Harry was heard talking about the sacrifices that veterans and their families make while serving their country.