"The Just War tradition ... was not framed in the abstract. It represents a careful attempt, gradually and pragmatically developed over many centuries, to put some moral discipline, some humanity, into the business of armed conflict without imposing a straitjacket so rigid as completely to preclude effective action against grave wrong."
General Sir Charles Guthrie was Chief of the Defence Staff from 1997-2001. Sir Michael Quinlan was PUS at the MOD from 1988-1992. They know whereof they speak.
I know that the people involved at the sharp end of conflict do tend to think about what they do and why they do it. What is really good about this book is having a couple of practitioners explaining how the Thomist principles of the Just War apply today.
Add to that a beautifully produced book, a hardback that lies flat without the spine cracking. £10 for 50 pages might seem a bit steep (only £7 from Amazon), but if you can't afford it, ask the library to obtain a copy. This is an important book.