The authorities of the Independent State of Croatia used a different method in their treatment of the Serb population. Throughout the year of 1942, they conducted total “cleansing of villages”. The population would be deported to the camp, the houses would be looted and burnt. Most frequently such devastated villages would be included into the Jasenovac Camp System. Camp farms were formed there where a certain number of prisoners performed seasonal agricultural work. When the winter came, they became unnecessary and were killed. Towards the end of May 1942, the entire Serbian population of Bosanska and Hrvatska Dubica was deported to the camp this way. Instead of Serbs, these two small towns were colonized by Croats, most of whom were from Herzegovina area bust also by Moslems from the nearby village of Orahove. Even the Serbs who were converted to Roman-Catholic region in 1941 were not spared in these actions of Ustashas. The biggest exodus of the Serbian population took place in the summer of 1942. On June 10, 1942 the operation “Western Bosnia” started. Around 30,000 Germans, Ustasha and Home Guards launched an offensive on the Kozara mountain where around 3,500 soldiers of the 2nd Krajina National-Liberation Movement’s squad were located. Members of the Serbian population from the villages lying under the Kozara mountain tried to find refuge in this mountain. After German-Croatian forces managed to tighten the grip around the Kozara mountain, 80,000 civilians were trapped inside. While the operation was officially proclaimed completed on 17 July, German-Croatian units conducted “cleansing” of the Potkozarje area until the second half of August. The consequences for the local Serbian population were tremendous. Over 68,500 inhabitants were deported to the Jasenovac camps. Deportations to the camp were followed by everyday killings of civilians.

Men would be separated from their families. Older ones would immediately be taken to Donja Gradina and killed, whereas those younger would be taken to the Camp III Ciglana. Upon arrival of a new group of men to the camp, members of the previous group would be taken to Gradina and killed. One part of men were taken to the Sajmište Camp in Zemun. Those of working age would be taken from Zemun to the Third Reich camps, whereas others would be transported back to Jasenovac on trains, in harsh conditions. They stayed for days in overcrowded cattle wagons without food and water. On 28 August 1942, a composition transporting 5,000 to 6,000 people closed in 79 cattle wagons entered the Ciglana camp. Around half of them died during transportation. The ones that had survived were transported across the Sava River to Gradina and killed.

Around 23,800 children of the age of up to 14 from the Kozara area were taken to the camps. Over 10,000 children ended up in the Camp V Stara Gradiška, 5,650 in the villages of Mlaka and Jablanac that served as Jasenovac farms, 1,300 in the Ciglana camp, around 1,300 in the Sajmište camp, with the rest ending up in various temporary camps in the wider camp area.
In the Stara Gradiška concentration camp, children were forcibly separated from mothers who were either killed or taken to the Third Reich as a labour force. Those children stayed in an open air until a children’s camp was established in one of the buildings, fenced with barbed wire. Children lied on the floor in rooms without furniture. Without any care and help most of them died. Their dying of hunger and diseases did not seem to be enough for the Ustashas, but they killed them too. One part of children was suffocated by poisonous gas. It is estimated that out of 10,000 children who went through the Stara Gradiška concentration camp some 3,000-3,500 were saved. They were saved by activists of the Croatian Red Cross as part of an action of by Diana Budisavljević.