The preliminary work for founding the camp began at the latest on 24 July 1941, when the Directorate for Improvements and Regulatory Works of the Independent State of Croatia ordered the timber for the construction of two wooden barracks in Jasenovac.
The site chosen for the camp was on the left bank of the River Sava, close to the village of Jasenovac, since it was on the Zagreb-Sisak-Novska railway line, and was a wide, level area, easy to supervise, and difficult to attack. In addition, there was already an industrial plant belonging to the Bačić family (a chain shop, sawmill, brickworks, mill and electricity generator). The whole area was abundant in raw materials for continuing production – high quality clay for brick production and wood for the sawmill.
The area was frequently inundated and inaccessible, due to flooding from the Rivers Sava, Una and Veliki Strug, and the vicinity of Lonjsko Polje and Mokro Polje marshlands.
The Ustashas justified the founding of Jasenovac Camp to the public by explaining that the area needed improvement and that a large work-force would be needed in order to do so.
Jasenovac Concentration Camp consisted of several camp units, founded one after another in quick succession: Camp I (Krapje), Camp II (Bročice), Camp III (Brickworks) in Jasenovac, Camp IV (Tannery work detail) and Camp V (Stara Gradiška).
Prisoners carried out seasonal, agricultural work on the camp farms in Mlaka, Jablanac, Gređani, Bistrica and Feričanci.
The first prisoners were brought to Bročice or Krapje on 23 August 1941.
The first two camps, Bročice and Krapje, were disbanded in November 1941, when many of the prisoners were liquidated and the survivors moved to Camp III (Brickworks), which from that point onwards operated as a death camp.