Robert Fisk is a multiple award-winning journalist on the Middle East, based in Beirut.

In 1942, in Nazi-occupied Warsaw, a Polish postal official working for the resistance opened a letter sent by a German soldier to his family.

Inside was a photograph which so shocked the man that he forwarded it to the Polish underground; thus it fell into the hands of a brave 16-year-old called Jerzy Tomaszewski, one of whose tasks was to pass on evidence of German atrocities to London so that the Allies could publicise Nazi cruelties in Eastern Europe.

Tomaszewski made a duplicate of the photograph for London and kept the original. He is still alive and, more than 60 years later, allowed freelance documentary photographer and writer Janina Struk to see the precious and terrible evidence – from which she made a perfect copy.

I will let Struk describe the photograph in her own words as they appear in her terrifying new book Private Pictures – about the private photographs taken by soldiers, from the Boer and 1914-18 wars through to the post-2003 US invasion of Iraq. "Somewhere near the small town of Ivangorod in Ukraine," she writes, "a German soldier points his weapon at a woman with a child in her arms. She has turned away from the soldier and wrapped herself around the child. Her foot is lifted from the ground as though she might be moving away from the soldier or perhaps the shutter has caught the moment the bullet has hit her....