Something you might like to also consider in relation to your unit question is the concept of a'just war'. This idea was first suggested by St Thomas Aquinas and has been used by many, including George Bush, to justify military action. Bush used it to justify the war in Afghanistan.
You know I was toying with that as the unit question: What is a "just" war?. I was concerned that the readings I wanted to do with the students wouldn't necessarily support the question. Do you have a concise approachable Aquinas reading I could share with these lads? Thanks so much for commenting on our blog!