Worst Possible Scenario

I've been reading The Untold War by Nancy Sherman for the past few days; it's really rather interesting reading about the different soldiers and what they've had to go through.

One of the things that stuck out the most to me, though, was the following passage.

I ask Quinby what would be one of the hardest situations he might face as a junior officer. Without hesitation he sketches a scene in which soldiers case a house harboring suspected terrorists. A soldier ends up killing innocent civilians, maybe because he was "scared," "stressed out" or caught up "in a chaotic gun fire." Or maybe, it was "due to sloppiness," "ignorance," or "poor discipline." "That's the sort of thing which I think would probably weight most heavily on my mind and give me a lot of trouble - being responsible for the accidental killing of someone who's completely innocent" when "it could have been avoided."
- The Untold War (pg. 36)

This is the basis for so much of the story. There's one half of the psychology and the psychological disorders that follow it which come from the dedication to the war and the people around them; the tight knit family unit that becomes your life.

But then there's this - just dealing with humanity. This is the other half of where the psychology comes from. How can you deal with killing another human being? Whether it's the enemy that's firing at you - after all, they're people too - or because they're civilians who just happened to be in the wrong place at the wrong time.

The effects of that and how soldiers deal with that are the most interesting part of military psychology to me, I think. Any potential readers out there have any thoughts?