Up to the end of 1941, the penitentiary in Stara Gradiška, downstream from Jasenovac, was used by the Ustasha authorities as a prison and assembly point for forced internment. The first group of prisoners, mostly Serbs and Jews, was brought from Slavonski Brod, Bosanska and Nova Gradiška in May 1941.
The Third Bureau of the Ustasha Surveillance Service ordered the Stara Gradiška penitentiary to be turned into a camp for the political rehabilitation of Croatian prisoners. Shortly after, groups of male and female prisoners were brought from Lepoglava Prison, Danica camp and various Zagreb prisons. A legal injunction ordering the abolition of the penitentiary and institution of forced labour in Stara Gradiška, dated 19 February 1942, allowed the penitentiary to be turned into a concentration camp with many purposes.
Although the camp was officially formed in 1942, the Ustashas began bringing and accommodating detainees to the existing penitentiary as early as the end of 1941. The first detainees were former detainees from the Danica camp near Koprivnica, and a group of prisoners from Zagreb prisons.
The Stara Gradiška camp was the second largest camp in the Jasenovac camp system, and it had its own specifics. Although it was first conceived as a place for the political re-education of Croatian citizens, even before the official establishment of the camp, Serbs, Jews and Roma were imprisoned there on the basis of national and religious affiliation. Citizens of Croatian nationality were also detained on the basis of the Legal Provision on Unwanted and Dangerous Persons, which provided a legal framework for imprisonment on political grounds.
The Stara Gradiška camp was also a children's camp, and a camp where women were imprisoned. A large number of children were brought to the camp together with their parents during the offensive on Kozara. In the camp, the children were separated from their parents. Unlike Camp III Ciglana, where all detainees were housed together, regardless of nationality and religion, in Stara Gradiška the detainees were separated, as can be seen in the example of the women's camp. Croat and Muslim women were housed in the Croatian Women's Camp, and Serb and Jewish women in the Tower, a dark and damp fortress building.