Ravensbrück was never intended as a death camp. The only concentration camp built entirely for women, it was planned by Himmler as a place of labour and re-education for prostitutes, Gypsies, Jehovah’s Witnesses and vagrants – all the ‘undesirables’ of the new Nazi Germany. But as Sarah Helm documents with meticulous thoroughness, such was the level of brutality that the women died, first in their tens, then in their hundreds and finally in their thousands. Of the 130,000 women estimated to have entered the camp during the six years of its existence, as many as half, and possibly three-quarters, did not survive. The French ethnologist Germaine Tillion, who was sent there in 1943, described it as a place of ‘slow extermination’.

Ravensbrück took its name from a village fifty miles north of Berlin, which stood on the edge of a lake surrounded by forests and flat marshy land. Locals called it the ‘little Siberian Mecklenburg’ on account of the glacial winds coming from the Baltic. The first 867 women arrived on 15 May 1939. They were stripped, washed, checked for lice and handed blue and white striped dresses and jackets, socks, wooden clogs and a white headscarf. Each was given a number and a coloured triangle made of felt to be sewn onto their clothes: black for prostitute, beggar or petty criminal, green for habitual criminals, lilac for Jehovah’s Witnesses. They were put to work shovelling sand. After the outbreak of war came women from all over the newly occupied territories, of every age and speaking many different languages; they included resisters, communists and Jews – though there were never very many of these, since Germany itself was to be rendered Judenfrei, free of Jews. Some brought children; others arrived pregnant, though very few of the babies were allowed to survive. The barracks, built on a vast square of rough grey clinker and laid out in orderly rows, were soon overflowing. There was never enough food and disease of every kind was rife.

Ravensbrück, as Helm describes it, was from the first a place of terror, ruled over by sadistic young female guards and kapos. There was Dorothea Binz, the pretty daughter of a forester, who delighted in humiliating and torturing the inmates, Gertrud Rabenstein, who trained her Alsatian to attack people in striped clothes, and Ruth Neudeck, who used her silver-handled whip freely on all who annoyed her.

It was in the summer of 1941 that lists of the old and the sick were drawn up, the ‘useless mouths’ unable to work as slave labourers in the surrounding war factories. Dr Friedrich Mennecke was in charge of the ‘mercy killings’, calling his selected victims ‘portions’. Then came the medical experiments on healthy prisoners, the injections of bacteria, the amputations, the sterilizations. The Revier, or infirmary, was home to the Kaninchen, the rabbits, survivors of the experiments carried out by Professor Karl Gebhardt and Ernst-Robert Grawitz, who also happened to be the president of the German Red Cross. And as ever more women arrived, so ways had to be found to dispose of them. Mass executions and lethal injections dealt with some; others were taken to a newly built gas chamber or dispatched to be gassed elsewhere.

Little was initially known about Ravensbrück because the camp lay behind what quickly became the Iron Curtain and because, when the SS pulled out in the spring of 1945, just before the arrival of the Red Army, they destroyed most of the camp records. It was only in the 1990s that accounts began to appear, often by feminist historians eager to remember the women whose stories had been overlooked. When Bernhard Strebel published his great work on Ravensbrück in 2003, Das KZ Ravensbrück, complete with over 200 pages of notes and appendices, it seemed as if all that needed to be written had been discovered. But Helm has returned to the memoirs, letters, papers, reports and testimonies prepared for the trials of the guards and doctors, and also interviewed as many former prisoners and their captors as she could find. There is much here that is new, and not the least of the book’s strengths is the way that she gives a voice and an identity to a vast number of forgotten women. Hardly surprisingly, this is not a book for the squeamish, nor, perhaps, at well over 700 pages, is it for the casual reader. But it is a work of impressive scholarship.

And, terrible as the stories of constant brutality and suffering are, it is impossible not to be affected by the days of liberation, as recounted by Helm. On 30 April 1945, the Red Army reached Ravensbrück. The SS had fled and there were not many women left. A few had already been rescued through deals brokered by the Swiss and the Swedes; others had been dispatched to camps out of reach of the Allies; others still had taken off on their own into the countryside in search of help. Those who remained were skeletal and very ill. Nonetheless, the arriving Russians soldiers, for the most part very drunk, embarked on an orgy of rape and murder. While much of this was directed at the German civilians they found in the neighbourhood, they did not spare the surviving Ravensbrück women, many of whom were raped. As one Red Army intelligence officer told Helm, ‘One should understand that it was a terrible, terrible monstrous war and everyone had gone completely inhuman.’