Zelengora is a mountain range in the Sutjeska National Park. It has a highest altitude of 2,014 metres and it is located at the border with Montenegro, divided between 3 municipalities: Gacko, Kalinovik and Foča.
Zelengora is now known as “a wilderness of outstanding beauty”.The eroded peaks of Zelengora that emerge from large mixed forests, attract, also because of the remoteness of the area, relatively few hikers. The wildness of the nature and the complete lack of signs of modern civilization gives these mountains a special appeal. The area around Orlovačko Jezero – and elsewhere – though, bears visible traces of historical habitation. The protection as part of the Sutjeska National Park of a large area of these mountains safeguards the integrity of the wilderness. A marked trail leading to the highest summit, Bregoč (2015 m.), starts at Orlovačko Jezero.
In 1943, Zelengora became the scene of fierce combat during the World War II, especially in a decisive phase of the Battle of the Sutjeska. By means of an operation called Fall Schwarz, the German occupational forces tried to encircle and destroy the YNLA, the partisan forces of Marshal Josip Broz Tito who had taken positions around Durmitor mountain in present Montenegro. Tito planned to break out of the encirclement towards the north across the river Sutjeska. In a battle that started on 5 June 1943, Partisan units of the YNLA 2nd Dalmatian Brigade took up positions in order to enable an escape of the YNLA forces through Zelengora. They were engaged by the German 118th Jäger Division. In spite of exhaustion, illness and dwindling munition supplies, the partisans of the 2nd Dalmatian Brigade held out against the far superior German forces until they were strengthened by the 1st Majevica Brigade on 9 June and were enabled to retreat in order to join the YNLA on 10 June. By that time, the 2nd Brigade had lost two thirds of its numbers, but had been successful in stalling the German advance sufficiently to allow Tito’s forces to cross the Sutjeska river and break out of the German encirclement.