An uprising in Croatia and western Bosnia started on 27 July 1941 with
Drvar uprising in the area of Drvar and Bosansko Grahovo in Bosnian Krajina. The uprising was nominally under the command of the local Communists. However, the Communists were few in numbers and a large number of insurgents were influenced by the Chetniks and local pre-war politicians that spread anti-Croat propaganda and advocated for a Greater Serbia. The rebel groups attacked NDH institutions and ambushed Ustaše and
Home Guard forces sent as reinforcements. Although they were ideologically on different sides, the
Chetniks and the Communists formed an alliance in order to balance against the increasing power of the Ustaše. , the commander of the
Croatian Home Guard On 27 July the Ustaše lost control of
Drvar. In the village of Trubar near Drvar, a Roman Catholic priest,
Waldemar Maximilian Nestor, and his parishioners were
killed by the insurgents. The NDH forces encircled Drvar, but lacked the artillery to capture the town. Eight battalions and several batteries were sent from Zagreb to the Drvar area, where an estimated 4,000 armed insurgents were located. 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. From 29 July to 2 August, the town of
Gračac was under siege. Gračac was defended by Ustaše and Home Guard forces, in total about 2,000 soldiers. Actions by the insurgents jeopardized
Donji Lapac, which the Ustaše had to leave. The rebels entered the village on 30 July without a fight. The Italian Army in the area was not a target of attacks, the insurgents even asked them for protection against the Ustaše. 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 2 August the rebels looted and burned the Croat village of
Boričevac. The majority of the population, 2,180 people, fled to
Kulen Vakuf, a large village near Drvar, before the insurgents entered. 55 remained in the village, mostly women and elderly, all of whom were killed. Kulen Vakuf, whose garrison was under the command of captain Vladimir Veber, was encircled by rebel forces.
Stevo Rađenović was labeled by the Italians as the political leader of the Serb resistance movement in Lika. The rebellion spread to North Dalmatia near the town of
Knin, which was directly endangered. The command of the city was completely taken by the Italians. Reports from the Ustaše recorded their dissatisfaction with the actions of the Italians, indicating the Italian authorities were giving refuge and support to the Chetniks. General
Mihajlo Lukić of the 3rd Lika Brigade was given the task of suppressing the uprising in Lika and the destruction of the rebel units. 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. The operation ran according to plans and in the first two days NDH forces managed to capture significant territory. On 19 August NDH troops reached Gornji Lapac where they found no resistance. A vanguard of the Ustaše and Home Guard troops, sent towards Boričevac, was ambushed and the offensive was halted. The rebels then strengthened their blockade of Kulen Vakuf and villages along the left bank of the Una River. On 4 September they attacked and destroyed the village of
Ćukovi. Although the local Muslims were not members of the Ustaše, the village was captured to completely encircle Kulen Vakuf. Veber tried to break through from Kulen Vakuf to
Bihać to evacuate the population during the night on 5–6 September. He had a Home Guard and Ustaše battalion and Muslim militia at his disposal. As the convoy left Kulen Vakuf, the rebels quickly crossed the Una and seized control of the village. The rebels attacked the retreating column and killed around three hundred refugees. A percentage of the refugees managed to reach Bihać, but about a third were captured. 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. Another 900, also mostly women and children, were held in a meadow, while about 380 male captives were transferred to another village. A percentage of the prisoners held at the meadow were butchered by the rebels and locals. About 50 tried to escape, but were captured and killed, their bodies thrown into a pit. Then, the Communists and rebels opposing the killings of the captives intervened. Kulen Vakuf was burned to the ground. The NDH lacked the forces to suppress the rebellion. The Germans could not divert their troops as all available forces were on the eastern front. The Italians, on the other hand, were able to provide assistance, but agreed to it only to strengthen their own influence over NDH. 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. In late 1941 the Italians re-occupied several previously NDH-held towns in the Bosnian Krajina. In early October the Italian 5th Corps re-occupied Kulen Vakuf. ==Commemoration==