It is December 1937, and the second Sino-Japanese war is approaching its climax.

Japan, having successfully invaded Shanghai, now looks towards the ancient capital city Nanking (now Nanjing) in hopes that this final conquest will end the war. China are forced to retreat their main forces from the capital, still wounded from their earlier conflict. They leave de facto control of the city to German citizen John Rabe, a businessman for Siemens AG and staunch Nazi, serving as a Deputy Group Leader in the Nazi Party. In December 13 1937, Japanese troops enter Nanjing.

If Nanjing sounds familiar, it is probably from the following horrific events now known as the Nanjing Massacre, or the Rape of Nanjing. In her book The Rape of Nanking, one of the most detailed recounts of this event, author Iris Chang estimates 40,000 to 300,000 citizens were murdered over the next few weeks, with at least 20,000 cases of rape, ranging from children to elderly women, alongside countless examples of forced incest.

As most of the westerners flee from the incoming massacre, 22 foreigners choose to remain: one of them being John Rabe. Throughout all this, John Rabe is granted a small area in Nanjing that is exempt from this brutality – as a German Nazi, the Japanese has agreed to not attack areas without Chinese civilians. Rabe subsequently sets up the Nanking Safety Zone to provide Chinese refugees with food and shelter from the massacre. In a letter to Hitler, Rabe explains that “There is a question of mortality here… I cannot bring myself for now to betray the trust these people have put in me, and it is touching to see how they believe in me.”

Through his efforts in the Safety Zone, historians have estimated Rabe saved approximately 250,000 Chinese civilians from the Nanjing massacre. One notable way Rabe succeeded in these efforts is through using the Nazi flag to construct shelters for the refugees camped outside his house. When the Japanese see the Nazi Swastika, they recognise it as a symbol of foreign security and leave the residence alone.

Florian Gallenberger, director of the documentary John Rabe, notes this paradox and what it can teach us about our potential for good:

“That is such a crazy thing that icon – rightfully the icon – of the murdering of millions of people in a different place, in a different moment, became a symbol of security… That it’s not just black and white but many shades in between, and that these stories with those many shades really help you to understand history…

“The outstanding thing about [Rabe] is that he was actually a quite normal person. He was not this kind of superhero type. In the situation that he got into, suddenly, he became more and more brave, then more and more daring, and more and more ready to risk his life for his values. And I think that’s what really interested me, to tell the journey of a normal, average person who discovers his own greatness. Because that’s a potential that’s probably within all of us.”