During a war people are encouraged, through propaganda, to dehumanise the enemy, it makes it easier to kill them that way. The fact is, though, that they are human beings. After the second world war many Germans claimed they were just following instructions when they committed the many atrocities that occured. Naturally, citizens of US, Aust, UK etc, were still thinking of them as monsters and this suggestion was laughed off.

About this time Stanley Milgram was a young PhD student in Pyschology at Harvard University. Of Jewish descent he had it in his mind (we suppose) to prove that there was some flaw in the German psyche that enabled them to obey instructions to torture and murder Jews and Gipsies the way they did. By way of proving that decent US citizens would not do this he constructed an experiment in which participants, ordinary US citizens, believed they were delivering increasingly high voltage electric shocks to subjects. (they weren't of course but they didn't know that)

Even when the "subjects" were displaying agony and screaming for mercy the volunteers, under instruction, continued to increase the voltage they thought they were delivering. 60% of participants continued to a level that they knew may kill the subject. These were ordinary US citizens "torturing" other US citizens! The experiment has been repeated in other countries with similar results. Interestingly best results are obtained when the person instructing them is wearing a white coat.

We like to think that we are capable of independant thought and judgement but the fact is that, when someone in authority tells us to do something, few of us have the strength to say "No".

PS. The experiment scarred some of the participants for life. It is not easy learning that you are capable of torture and murder simply because someone in a white coat tells you to. We could not ethically perform this experiment today but it taught us some valuable things about ourselves.