It was 1945. The second world war was over and in the German city of Nuremberg 21 Nazi leaders were on trial for war crimes. By far the youngest member of the prosecution team was 22-year-old US army private Richard Sonnenfeldt, a Berlin-born Jew whose parents had sent him to England at the age of 15 to escape Nazi persecution. Still only 16, he had been deported by Britain as an “enemy alien”, ended up in the US and served as an American infantryman helping liberate his native land.