Military brothels were set up by the Nazi state to service Wehmacht and SS soldiers. These establishments were staffed by women rounded up in occupied countries. Women and girls as young as 15 were randomly snagged off the streets and taken to the brothels.

According to records, a minimum of 34,140 European women were forced to serve as prostitutes during the German occupation of their own countries along with female prisoners of concentration camp brothels. In many cases in Eastern Europe, teenage girls and women were kidnapped on the streets of occupied cities during German military and police round ups. Wikipedia

Some of the women were forced to endure abortions and sterilization. These sometimes resulted in deaths.

The Foreign Ministry of the Polish government-in-exile issued a document on May 3, 1941, describing the mass kidnapping raids conducted in Polish cities with the aim of capturing young women, as young as 15, for sexual slavery at brothels run by the German military. On top of that, Polish girls as young as 15 – classified as suitable for slave labor and shipped to Germany – were sexually exploited by German men. In Brandenburg, two Polish Ostarbeiter teens who returned home to Kraków in advanced stage of pregnancy, reported to have been raped by German soldiers with such frequency that they were unable to perform any of the worker’s designated labor. Wikipedia

The German high command did not want their soldiers developing relationships with women in conquered areas. Soldiers were allowed to use official brothels but not allowed to fraternize with locals.

Conditions in brothels were brutal. The women were often raped by up to 32 men per day; the visiting soldiers were allocated 15 minutes each at a nominal cost of 3 Reichsmarks per “session” between the hours of 2 p.m. and 8.30 p.m. Approximately 35,000 Jewish women and girls were forced to work in brothels, with each woman being made to service seven or more men per day. Those who were visibly pregnant were sometimes released, but would not go back to their families, so as not to shame them. Wikipedia

The Nazis also had brothels near or in concentration camps. Joy Division was the name given to such a brothel in Auschwitz according to the novel “House of Dolls.”