Throughout German-occupied Europe, the Germans arrested those who resisted their domination and those they judged to be racially inferior or politically unacceptable. People arrested for resisting German rule were mostly sent to forced-labor or concentration camps. The Germans deported Jews from all over occupied Europe to extermination camps in Poland, where they were systematically killed, and also to concentration camps, where they were used for forced labor. Transit camps such as Westerbork, Gurs, Mechelen, and Drancy in western Europe and concentration camps like Bolzano and Fossoli di Carpi in Italy were used as collection centers for Jews, who were then deported by rail to the extermination camps. According to SS reports, there were more than 700,000 prisoners registered in the concentration camps in January 1945.
US Holocaust Memorial Museum