The range of what we think and do is limited by what we fail to notice. And because we fail to notice that we fail to notice there is little we can do to change until we notice how failing to notice shapes our thoughts and deeds.
We are all murderers and prostitutes - no matter to what culture society...
You do have to change things as warfare changes.
Always there has been some terrible evil at home or some monstrous foreign power that was going to gobble us up if we did not blindly rally behind it.