The whole concept of "good vs. evil" is a human construct. Our species has used it to dehumanize those we wage war against since the earliest days of organized militaries. It transcends culture, nationality, and our time on this planet; it has always been and will always be.
Benjamin Franklin nailed it when he said, "Fatigue is the best pillow." True story, Benny. There's nothing like pushing your body so far past exhaustion that you'd willingly, even longingly, take a nap on a concrete slab.