Women guards of the Bergen-Belsen Nazi concentration camp, including Herta Bothe (right) and Irma Grese (second right) are seen after capture by British troops who liberated the camp, April 1945.

Diane Kruger (pictured above in character) portrays an inmate at Ravensbruck who is made a Kapo - a senior prisoner given the duty of overseeing other prisoners - in Each of Us.

Women guards are often portrayed as masculinised sadists, but the more prosaic – and shocking – truth is they were often just normal women who acclimatised to the brutality of the Nazi regime.

In 1942, the Nazis decided that forced laborers in concentration camps would work harder if they were promised sex -- so they made female prisoners work in brothels for them.

An account of brothels for concentration camp workers details a little-known chapter of Nazi oppression and degradation in World War II.

Female SS guards enjoyed home comforts at a camp where they tortured thousands of inmates.

Some 3,500 women worked as Nazi concentration camp guards, and all of them started out at Ravensbrück. Many later worked in death camps such as Auschwitz-Birkenau or Bergen-Belsen.