Forced exhausting labor was one of the hallmarks of the lives of detainees in the Jasenovac camps. At first, under the expert guidance of Franjo Beretin from the technical section of the Ministry of Public Works, the detainees fenced the camp with wire, built barracks and scouts, and an embankment to protect the camp from floods. Works on repairs and commissioning of industrial facilities were rather slow, so that most of the facilities did not start operating until February 1942.
The formation of working groups and their deployment by facilities was carried out during the winter of 1941/1942. The work was divided into internal (facility work) and external (work on camp economies, logging, etc.), and the working groups were named according to the type of work they performed. The official number of the group was marked with Roman numerals or letters (I The chain factory, II Brickworks, III Sawmill, IV Tannery).
Work in women's working groups was performed on camp economies, tailory, laundries, etc. The number of detainees in the working groups was not equal, ranging from a few hundred to at least a dozen. The larger groups were divided into hundreds or tens, and each had a working leadership composed of the detainees themselves.
The first commander of the labor service was Ljubo Milos, an Ustasha lieutenant. In 1942, he was succeeded by Dominik Hinko Pićili, an Ustasha colonel.
In the Stara Gradiška camp, the commander of the labor force was Petar Nemet, an Ustasha lieutenant who was hanged in 1944 for assisting detainees. The camp economies of Mlaka, Jablanac, Gređani, Bistrica and Feričanci were worked on during seasonal agricultural work. Upon completion of the works, most of the detainees were killed.