Prince Harry claims joining the military gave him a sense of purpose after years of trying to deal with the death of his mother, Princess Diana, in 1997.
Last week, early copies of his memoir Spare, which had been published in Spain, revealed Harry had killed 25 people in Afghanistan during tours of duty there.
In his memoir, he revealed he executed the killings when serving as a military helicopter pilot, describing the victims as "chess pieces removed from the board."
In the section, the 38-year-old recounted his two tours of Afghanistan, first as a forward air controller in 2007-2008 and again in 2012, when he was a co-pilot gunner in Apache attack helicopters, as well as the number of people he had killed.
"It wasn't a statistic that filled me with pride but nor did it leave me ashamed," Harry wrote, according to the Spanish version of the book. "When I found myself plunged in the heat and confusion of combat I didn't think of those 25 as people.
"They were chess pieces removed from the board, Bad people eliminated before they could kill Good people."
Speaking to 60 Minutes' Anderson Cooper in an explosive interview in which he branded Queen Consort Camilla "dangerous" and revealed he'd spent over a decade believing his mother Diana was still alive, Harry said joining the armed forces allowed him "to focus on a purpose larger than myself."
"My military career saved me in many regards. It got me out of the spotlight from the UK press, I was able to focus on a purpose larger than myself, to wear the same uniform as everybody else.
"I felt normal for the first time in my life. I was able to accomplish some of the biggest challenges I had ever had. You don't get a pass for being a prince," he told Cooper.
"I was a really good candidate for the military. I was a man in my 20s, suffering from shock, but I was now in the front seat of an Apache, shooting it, flying it, monitoring four radios simultaneously and being there to save and help anybody who was there on the ground with a radio, screaming we need support, we need air support. That was my calling, I felt healing from that."
Harry's comments add further fuel to the fire of those already angered by his admission that he'd killed 25 people.
Abdul Qahar Balkhi, spokesperson for the Taliban-led Afghan foreign affairs ministry, has criticised the initial comments, responding: "The western occupation of Afghanistan is truly an odious moment in human history and comments by Prince Harry is a microcosm of the trauma experienced by Afghans at the hands of occupation forces who murdered innocents without any accountability."
Former Royal Marine Veteran Ben McBean also criticised the prince on Twitter following the revelation.
"Love you #PrinceHarry but you need to shut up! Makes you wonder about the people he's hanging around with. If it was good people somebody by now would have told him to stop," McBean tweeted.
Prince Harry wrote he was able to see how many people he killed in combat because they were "in the era of Apaches and laptops," and therefore able to know the exact number of fatalities.
Watch Prince Harry's interview with Anderson Cooper on ThreeNow.
