The book On Killing is really great. I can't recommend it enough. It's one of the most important books I've ever read considering the topic it deals with and how the military systematically extinguishes the natural instinct not to kill, and how important understanding desensitization is for our civilization in this era where violence can be inflicted on large numbers by so few and with such ease.
It's on my to-read list.

Somewhat unrelated but, there was a three part interview The Real News did with David Swanson some time ago, that I think you might like (well, at least I did

):
"Lies and War - David Swanson on Reality Asserts Itself"
https://www.youtube.com/watch?v=CzwaSbWD8C0 - "On RAI with Paul Jay, David Swanson, author of "War is a Lie", talks about becoming a full time activist for peace"
https://www.youtube.com/watch?v=BM5qIvVLGg0 - "On RAI, Paul Jay and David Swanson discuss the culture and economics of war"
https://www.youtube.com/watch?v=LIcOdilpXUU - "On RAI with Paul Jay, David Swanson says that nonviolent campaigns have been more successful than campaigns of violence"
I particularly liked the idea they explore in the second video: that war is, in a sense, a "cultural invention", or that at the very least, the culture of a society has a great deal of influence in either promoting or rejecting the practice of war - as opposed to, war simply being just a part of human nature, and fundamentally unavoidable; or mainly economic/resource driven; or perhaps due to the way societies are structured and who has power in them.
The whole thing is a bit long though: about an hour.
Thanks for this. I will look into it when I have an hour to watch.