All occupying armies become Nazis, all soldiers in occupying armies commit or permit atrocities. You would and I would, not because we are intrinsically evil but because doing evil is an inevitable consequence of being part of an invading and occupying army. Each war crime is a consequence of the initial war crime, which is the decision to invade or attack a country that has not attacked or threatened your own. In a democracy the people responsible for this decision are, in order of culpability, those who command it, those who implement it and those who consent to it, the government, the military and the citizenry. Those with greatest power bear the greatest responsibility but to the extent that we live in a democracy we all have some power.