A few years back I picked up a book titled "On Killing: The Psychological Cost of Learning to Kill in War and Society" by Lt. Col. Dave Grossman. Lt. Col. Grossman has, in my opinion, done some controversial things, but I found his book "On Killing" to be insightful.
"On Killing" contained one passage that was both illuminating and inspiring and it didn't come from Lt. Col. Grossman, but from a grizzled old veteran he was interviewing. The passage can be found in Section IV "An Anatomy of Killing, All Factors Considered", Chapter 5 "Aggressive Predisposition of the Killer, Avvengers, Conditioning, and the 2 Percent Who Like It", page 183:
"One Veteran I interviewed told me that he thought of most of the world as sheep: gentle, decent, kindly creatures who are essentially incapable of true aggression. In this veteran's mind there is another human subspecies (of which he is a member) that is a kind of dog: faithful, vigilant creatures who are very much capable of aggression when circumstances require. But, according to his model, there are wolves (sociopaths) and packs of wild dogs (gangs and aggressive armies) abroad in the land, and the sheepdogs (the soldiers and policemen of the world) are environmentally and biologically pre-disposed to be the ones who confrnot these predators."
I've read elsewhere that the sheep are often afraid of the sheepdogs and resent them because they surely look and act an awful lot like the wolves and packs of wild dogs.
Lt. Col. Grossman goes on though: "These men are quite often armed and always vigilant. They would not misuse or misdirect their aggression any more than a sheepdog would turn on his flock, but in their hearts many of them yearn for a righteous battle, a wolf upon whom to legitimately and lawfully turn their skills."