The invisible ink which revealed concentration camp horrors

A secret letter written by Krystyna Czyż on the back of a camp envelope giving details of prisoners who were operated on, their camp numbers and the type of experiments carried out on them. Kalbar/TFN

In the darkest recesses of Hitler’s hellish concentration camp system, four young Polish Girl Guides were desperate for the world to know about the barbaric experiments that were being carried out on them.

On 21 September 1941, a group of 400 women from Lublin and Warsaw was taken to Ravensbrück, the notorious concentration camp for women near Berlin.

As TFN’s Stuart Dowell tells this week’s The Debrief, the group included four Girl Guides who had been arrested for involvement with the Polish Underground. They would go on to create the secret letter writing group.

Read the full story HERE.