Researchers estimate that some 4,000 female guards worked in concentration camps during the Nazi era. That was ten percent of the total guard personnel. Unlike male guards, the female guards did not belong to the SS. They were instead referred to as “SS auxiliary.” How and why women became guards varied. The good wages and employment in the civil service were one reason. The Ravensbrück concentration camp served as a training ground for most of the female guards. Their average age was twenty-five.