A retired commanding officer has accused Prince Harry of “turning against” his military family after “having trashed his birth family”.
In his memoir, the Duke of Sussex describes killing 25 Taliban fighters in Afghanistan as “chess pieces taken off the board”.
Ex-colonel Tim Collins said that was “not how you behave in the army”.
Prince Harry gives details about his time as a helicopter pilot in Afghanistan in his memoir Spare.
BBC News has obtained a copy of the book after it was put on sale early in Spain.
In it, Prince Harry reveals for the first time that he killed 25 enemy fighters – which is perfectly possible after two tours in the Helmand region of the country.
“It wasn’t a statistic that filled me with pride but nor did it make me ashamed,” he writes.
“When I was plunged into the heat and confusion of battle, I didn’t think about those as 25 people. You can’t kill people if you see them as people.
“In truth, you can’t hurt people if you see them as people. They were chess pieces taken off the board, bad guys eliminated before they kill good guys.
“They trained me to ‘other’ them and they trained me well.”
Responding to the prince’s comments, a senior Taliban leader Anas Haqqani tweeted: “Mr Harry! The ones you killed were not chess pieces, they were humans; they had families who were waiting for their return…
“I don’t expect that the (International Criminal Court) will summon you or the human rights activists will condemn you, because they are deaf and blind for you.”
Speaking to Forces News, retired-commanding officer Colonel Collins condemned the book by calling it a “tragic money-making scam”.
Referring to Prince Harry’s revelation that he killed 25 enemy fighters, Col Collins said: “That’s not how you behave in the Army; it’s not how we think.
“He has badly let the side down. We don’t do notches on the rifle butt. We never did.”
The ex-colonel, who gained worldwide fame for an eve-of battle speech to troops in Iraq, said: “Harry has now turned against the other family, the military, that once embraced him having trashed his birth family.
He accused Prince Harry of choosing an “alien” path and of “pursuing riches he does not need”.
“In the end, I see only disappointment and misery in his pursuit of riches he does not need and his rejection of family and comradely love that he badly needs.”