Prince Harry has been heavily criticised for revealing "sensitive" information about his time in Afghanistan - and accused of breaking at least four military codes.
In his highly-anticipated autobiography Spare, the Duke of Sussex said that he killed 25 Talibans during his second tour on the Helmand frontline while serving as an Apache helicopter co-pilot and gunner.
Harry wrote that he blasted enemy insurgents during six combat missions which involved the "taking of human lives" - and he did not think of those he killed "as people" but as "chess pieces" that were taken off the board.
Many former military personnel have slammed the Prince for revealing such specific details - with some suggesting it could affect his own safety and that of soldiers in the field.
Major General Chip Chapman, who fought in the Falklands campaign and has been the Senior British Military Advisor to US Central Command, has called Harry and his ghost writer "crassly and naively stupid".
Having the experience of writing his own book, Chapman explained that they require a legal and ethical read to look for any sensitive details on special forces and casualties.
"For him, who wants privacy and security, he's just opened himself up to every jihadist and nutcase out there," he told Times Radio.
Chapman admitted he had never come across "this body count mentality" in the forces, slamming Harry's claim of 25 kills as "slightly ridiculous".
Because the Prince was a Apache pilot who used cannons or missiles from a range some way away from the action, Chapman says there is no way he could ID or bury anyone.
"It's an awful lack of judgement and maturity," he adds. It's a naïve approach to how the military would act. And we talk about jus in bello conduct in war. This is a terrible conduct in peace."
In an excerpt from the Spanish version of Spare, which has been obtained by The Daily Telegraph after accidentally going on sale in Spain, Harry explained how he knew his exact number of kills because of the "era of Apaches and laptops".
He writes about how he watched each "kill" when he returned to base and described the insurgents as “baddies eliminated before they could kill goodies”.
The excerpt adds: "I made it my purpose, from day one, to never go to bed with any doubt whether I had done the right thing…whether I had shot at Taliban and only Taliban, without civilians in the vicinity.
"I wanted to return to Great Britain with all my limbs, but more than that I wanted to get home with my conscience intact."
Chapman believes Harry opening up about his conscience is the "one good thing" he says about his experience in the military - and should have been developed more in the book.
He adds: "We have a code of conduct. It's the values and standards of the military. He's broken at least four of those values. That includes respect for others, integrity, loyalty and selfless commitment."
A number of people have slammed Harry for going into such depth on his time in Afghanistan.
Veteran broadcaster Andrew Neil tweeted: "Harry's claim that he killed 25 Taliban is a nightmare, an absolute nightmare, for his security teams. How stupid can you be?"
While tweeting that he loved the Prince, Former Royal Marine Ben McBean said the royal needed to "shut up".
"Love you #PrinceHarry but you need to shut up! Makes you wonder the people he's hanging around with. If it was good people somebody by now would have told him to stop," he wrote.
Colonel Richard Kemp , former commander of British forces in Afghanistan, has told the Mirror: "All the good work Prince Harry did on behalf of the Armed forces has been undermined by his comments.
"Not only has he gone too far in talking about this in terms of himself but it may have repercussions for others.
"As a member of Royal Family he has to accept being something of an ambassador for the UK - so his comments may effect the security of his former comrades on foreign operations …"
The UK's former National Security Advisor also revealed he would have advised Prince Harry against his remarks.
Kim Darroch told Sky News: "Personally if I'd been advising the Prince, I would have advised against the kind of detail he goes into."
Lord Darroch, who was National Security Advisor from 2012 to 2015 before becoming Ambassador to Washington, added: "I believe it was a just war.
"And therefore what he has written about, how he justified to himself what he was doing, [I] understand and appreciate that.
"In terms of detail, I personally wouldn't have gone there. But it's done now."
Buckingham and Kensington Palaces have refused to content on the contents of the book, which hits the shelves on Tuesday.
This story is based off a translated version of Prince Harry ’s book Spare.
Spare is set to be released early next week at all book stores and can be bought online here.
What are your thoughts on Harry's new book? Have your say in the comment section below.
