The first wave of massacres Killing in the town began Process_start on 11 or 12 May 1941 , when a band of Ustaše led by Mirko Puk murdered Killing a group of Serb men and boys in a Serbian Orthodox church before setting Placing it on fire Damaging .

The following day , approximately 100 Serb males were murdered Killing by the Ustaše in the nearby village of Prekopi .

Further killings Killing in Glina occurred between 30 July and 3 August of that same year , when 700–2,000 Serbs were massacred Killing by a group of Ustaše led by Vjekoslav Luburić .

It was carried out Action in two phases within eastern Bosnia from 20 April to 13 May 1942 , with Ustaše militia and Croatian Home Guard forces Military_operation taking part Dispersal on the Axis side .

The operation was of limited effectiveness due to several factors , including preemptive action by the Ustaše militia and Italian delays .

For a time they ruled Control large parts of the region , after making accommodations with the Ustaše regime in May and June 1942 .

The uprising Change_of_leadership was started Process_start by the local population as a response to persecutions of Serbs by the Ustaše and was led by Chetniks and Yugoslav Partisans .

The German and Ustaše authorities realized Know that the city of Banja Luka and the iron mine in Ljubija were in danger and organized Arranging an offensive to destroy the movement .

During and after the battle , many thousands of Serbian civilians from Kozara were sent Sending to the Ustaše Jasenovac concentration camp .