General Sherman said it best: "War is hell, and you cannot refine it."
I suspect that one reason so many military personnel suffer from PTSD is from the shock of seeing what they themselves are capable of doing in combat, or what they inadvertently end up doing in the heat of battle. My father, who retired as a US Army Special Forces Group Sergeant Major, was once chasing a woman through a Vietnamese village because he thought she may have been a sapper; that the bundle she carried was a satchel charge. The chase became intense. As he rounded a corner of a hootch, he saw a door swinging shut and burst into the room. The woman and the baby she was holding were blown to pieces by a Thompson submachine gun. My father heard someone screaming, "Stop! Stop! Stop!" only to realize that it was he who was screaming and he who was pulling the trigger. He never was quite right in the head after that.
I was also in Special Forces during the Vietnam War. During our training, we received an "eight-hour block of instruction" in torture. They said the reason was to prepare us for what might happen to us if we were captured. Why do you suppose they took so much time to teach us so many techniques? They could have stopped after the initial warning: Don't wear your green berets in the field. If the Cong catch you, they'll nail them to your heads. (It had actually happened.) Do Americans torture captives? Do fat babies fart?
A final thought. We need to stop all this knee-jerk worshipping of all military personnel as "heroes." If everybody is a hero, then nobody is a hero, as the very word loses its meaning. Brave warriors are one in a thousand; true heroes are one in a million.
Those who see the world in black and white are limited in vision. General Curtis Lemay, US Army Air Corps commanding, said, "We better win this damn war or we'll all be tried as war criminals." His forces had been conducting saturation incendiary bombing which burned down most all major Japanese cities, slaughtering countless thousands of civilians. The Atomic bombs were just cherries on the cake. It could be argued that the Japanese of that generation deserved to roast alive in lakes of fire, but they no doubt would have reached a different conclusion had they won.
War is hell, and you cannot refine it.