leadership of the anti-Ustasha rebellion among the Serbs from Bosnia also developed in the form of the Chetnik movement and autonomous bands which were under command of Dragoljub Mihailović. Whereas the Partisans under Serb leadership were open to members of various nationalities, those in the Chetniks were hostile to Muslims and exclusively Serbian. The uprising in Bosnia and Herzegovina started by Serbs in many places were acts of retaliation against the Muslims, with thousands of them killed. A rebellion began in June 1941 in Herzegovina. On 27 July 1941, a Partisan-led uprising began in the area of Drvar and Bosansko Grahovo. It was a coordinated effort from both sides of the Una River in the territory of southeastern Lika and southwestern Bosanska, and succeeded in transferring key NDH territory under rebel control. On 10 August in Stanulović, a mountain village, the Partisans formed the Kopaonik Partisan Detachment Headquarters. The area they controlled, consisting of nearby villages, was called the "Miners Republic" and lasted 42 days. The resistance fighters formally joined the ranks of the Partisans later on. At the September 1941 Stolice conference, the unified name partisans and the red star as an identification symbol were adopted for all fighters led by the Communist Party of Yugoslavia. In 1941 Partisan forces in Serbia and Montenegro had around 55,000 fighters, but only 4,500 succeeded to escape to Bosnia. On 21 December 1941 they formed the 1st Proletarian Assault Brigade (1. Proleterska Udarna Brigada) – the first regular Partisan military unit, capable of operating outside its local area. In 1942 Partisan detachments officially merged into the People's Liberation Army and Partisan Detachments of Yugoslavia (NOV i POJ) with an estimated 236,000 soldiers in December 1942. Partisan numbers from Serbia would be diminished until 1943 when the Partisan movement gained upswing by spreading the fight against the axis. Increase of number of Partisans in Serbia, similarly to other republics, came partly in response to Tito's offer of amnesty to all collaborators on 17 August 1944. At that point tens of thousands of Chetniks switched sides to the Partisans. The amnesty would be offered again after German withdrawal from Belgrade on 21 November 1944 and on 15 January 1945. Operations Resistance and retaliation The Partisans staged a guerrilla campaign which enjoyed gradually increased levels of success and support of the general populace, and succeeded in controlling large chunks of Yugoslav territory. These were managed