The prisoners at Osthofen Concentration Camp were arrested because they had been politically active in left-wing parties or organizations. Most were members of the Communist Party of Germany (KPD) or the Social Democratic Party (SPD).
Among the detainees were also supporters of the Reichsbanner Schwarz-Rot-Gold, an organization devoted to defending parliamentary democracy, the Allgemeiner Deutscher Gewerkschaftsbund (ADGB), a confederation of German trade unions, the Catholic Young Man’s Association (Katholischer Jungmännerverein), the Catholic Center Party (Zentrum), as well as Jehovah’s Witnesses and Roma. There was also a remarkably large number of Jewish prisoners – somewhat unusual for an “early” concentration camp.
In the seventeen months of its existence, at least 3,000 men and a few women were detained in the barren factory for about three to four weeks under inhuman conditions. While no prisoner was killed in Osthofen, they were exposed to constant terror, abuse and humiliation by the guards. The Jewish prisoners suffered especially harsh treatment at the hands of their tormentors.