During the four years of its existence, the Ustasha regime carried out genocidal politics, in accordance Decrees issued by the government, against the Serbian population of the entire Independent Stare of Croatia, particularly in the regions of the Bosanska Krajina, Slavonia, Banija, Srijem, Kordun, Semberija and Lika.
As early as 1941, the Ustasha began persecuting Serbian Orthodox priests and re-baptising the Serbian Orthodox population, demolishing their churches, and also carrying out the first individual and mass arrests and murders of the Serbian population.
At a meeting at the German Embassy in Zagreb on 4 June 1941, the Nazis approved measures already taken by the Independent State of Croatia authorities to provide a final solution to the Serbian question in the Independent State of Croatia, by the forced transfer of Serbs to Serbia, mass killings in the field and deportation to concentration camps.
The deportation of Serbs, firstly the wealthy and respected, was organised right from the establishment of Jasenovac concentration camp in August 1941, so that by the beginning of 1942 they formed the noticeably largest group of inmates.
After the great German/Ustasha/Home Defence offensive on Kozara in the summer of 1942, tens of thousands of Serbian villagers, men, women and children, were taken to the Ustasha camps in Jasenovac and Stara Gradiška, with their portable possessions. Most of them were killed immediately.
Some were assigned to work details, which were formed in the winter of 1941/1942, but their numbers did not correspond to the proportion they formed of the victims of the Jasenovac killing fields.
The real number of those killed in Jasenovac Camp will probably never be ascertained, but it is a fact that the biggest group among them were Serbs. They died in various ways, in all the Jasenovac places of execution, especially Donja Gradina.