it's a book written by a westerner about the presence of zen buddhism in ancient japanese warfare. it also mentions that other buddhists stoutly opposed war.

I have been briefly to a zendo and was exposed to the basic meditative teaching that nothing living may ever be harmed. I believe this myself before going, so noticed its presence.

It's nice to learn that a problem may have happened before, of [the strongest peaceholding tools of the time] being used by a military for harm. I wonder how it resolved.