The 29-year-old royal served two tours of Afghanistan, one in 2007-2008 and a second in 2012-2013. In a powerful column for The Sunday Times, he said he was "hit" by the horror of what he had experienced while flying home with injured personnel in February 2008.
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Prince Harry at a briefing in Camp Bastion, Afghanistan, in November 2012
"I had never seen it first-hand," Harry wrote. "By 'it' I mean the injuries that were being sustained largely due to improvised explosive devices (IEDs).
"Loss of life is as tragic and devastating as it gets, but to see young lads – much younger than me... missing limbs... was something I never prepared myself for."
Harry has gone on to dedicate himself to helping injured servicemen and women. Next month, shortly before his 30th birthday, the prince's Paralympic-style Invictus Games will take place in London.
Prince Harry chats to former servicemen Andy Phillips and Daniel Whittingham about the Invictus Games
Harry came up with the concept of the tournament for injured service personnel after a 2012 visit to America, where he witnessed the Warrior Games and realised that sport could serve as a great motivation for rehabilitation.
"The premise is simple: set yourself a target, take your mind off all the negative thoughts and concentrate on the challenge in front of you, all while relearning to use your body," he said.
Of the 400 wounded men and women representing 14 countries at the Invictus Games, Harry added, "They want to put on a show for you. All are in different stages of their rehabilitation, some are Paralympians, others just want to use sport to get their lives back in shape."
The Invictus Games will take place in London's Olympic Park between 10 and 14 September.