The Japanese soldiers practiced a twisted version of Bushido where they considered that surrender was dishonorable and the people who surrendered were weak and should die, so they committed many war crimes including killing children and raping and killing women, saying that it's because of the Bushido code.
One way Diocletian brought short-term order to Rome was to "divide the empire" into to distinct spheres--in the hope that this would make it easier to manage.
