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

During the uprising numerous war crimes were committed against local Croat and Muslim population, especially in the area of Kulen Vakuf.

As NDH forces lacked the strength to suppress the uprising, the Italian Army, which was not a target of the rebels, expanded its zone of influence to Lika and parts of Bosanska Krajina.

After the independence of Croatia, 22 June was chosen instead as the Anti-Fascist Struggle Day and a national holiday, commemorating the earlier creation and resistance activity of the 1st Sisak Partisan Detachment.

During the Invasion of Yugoslavia, Ustaše, a Croat fascist and ultranationalist organization aboard, proclaimed the Independent State of Croatia (NDH) on 10 April 1941, supported by Germany and Italy.

[1][2] By May 1941, the Ustaše formed the Jadovno concentration camp in Lika where they incarcerated and executed thousands of ethnic Serbs and other prisoners, which led to the rebellion.

[3][better source needed] Large scale persecutions in the area started in June 1941, including ethnic cleansing of around 1,200 Serbs who were expelled to occupied Serbia by Vjekoslav "Maks" Luburić, whereas in the municipality of Srb, days ahead of the rebellion, Luburić's Ustaše forces murdered 279 Serb civilians in the villages of Suvaja, Osredak and Bubanj.

The rebel groups attacked NDH institutions and ambushed Ustaše and Home Guard forces sent as reinforcements.

[5] In the village of Trubar near Drvar, a Roman Catholic priest, Waldemar Maximilian Nestor, and his parishioners were killed by the insurgents.

[11] On 28 July, in the village of Brotnja in the municipality of Srb, 37 civilians were killed and their houses were looted and destroyed by Chetniks.

According to an Italian assessment, the uprising was primarily directed against the Ustaše regime, while the influence of the Communists had a secondary role.

On 17 August 2 battalions and a battery of cannons, numbering about 1,300 men, started an attack in order to relief Kulen Vakuf and connect with forces coming from Gračac.

Seventy were immediately killed and 400, mainly women and children, were returned in captivity to Kulen Vakuf and held at the police and railway stations.

On 26 August 1941 the NDH government reached an agreement that the Italians re-occupy the 2nd and 3rd zones in order to pacify the insurgents in those areas.

[27] Nevertheless, several anti-fascist organizations and the Independent Democratic Serb Party (SDSS) continued to commemorate this date as the first day of an antifascist uprising.