Anyone here who hasn't read A Tale of Two Cities by Charles Dickens should drop everything and go do so. If ever there was a work of literature that demonstrated the way misdeed breeds misdeed, that was it. It's a harsh reality of human existence, and it's very apt to make one sick when demonstrated in such obvious ways. I can't imagine how difficult it is for those soldiers to live and do what they do, especially in the light of the way the government has often treated them and restricted them, but they've manifested it in vile ways from time to time.
Seriously, go read the book. If it doesn't level your perspective and make you cry for the world, I'll eat my fucking hat.