this had occurred, and there were mass shootings of Serbs, which escalated the level of violence even further. In late May and June, 173 Serbs had been rounded up, tortured and killed in Nevesinje, and in early June, another 140 Serbs had been killed at Ljubinje. In response, Serbs attacked Ustaše officials and facilities, and conducted raids themselves, killing Muslim villagers. Uprising The NDH authorities only had weak forces in eastern Herzegovina at the time the mass uprising occurred, roughly equal to two Croatian Home Guard battalions, as well as gendarmerie posts in some towns. This was barely adequate to guard important locations, and was insufficient for offensive action. Deployed forces consisted of one company of the 10th Battalion in Trebinje, the headquarters and a reinforced company of the 7th Battalion in Bileća (the balance of the battalion being divided between Gacko and Avtovac), and a company of the 6th Battalion in Nevesinje. The remainder of the 10th Battalion was deploying to Trebinje at the time the rebellion broke out. 23–24 June The first indication that the situation had changed significantly was on 23 June, when a group of 200 Ustaše clashed with a group of rebels they estimated to number between 600 and 1,000. After an extended firefight near the village of Stepen, north of Korita, during which they suffered several casualties, the Ustaše also burned down four villages. They then entered two Muslim-majority villages in the area and arrested 13 Serbs who had not been involved in the earlier fighting. The arrested Serbs were transported north to Avtovac and shot. That night, all adult Serbs above the age of 16 in Gacko, northwest of Avtovac, were arrested, and 26 were immediately shot. The rest were transported west to a camp in Nevesinje. Over the period 23–25 June, 150 Serbs from the village of Ravno, southwest of Ljubinje, were arrested and killed at the gendarmerie post, and the remainder of the population fled to the hills. On 23 and 24 June, spontaneous mass gatherings occurred at several villages in the Gacko and Nevesinje districts. These rallies were prompted by the news of the German invasion of the Soviet Union, and those attending them voted to fight against the Ustaše. Professor Marko Attila Hoare states that the full-scale uprising resulted from the Ustaše retaliation against attempts of the Serbs of eastern Herzegovina to defend themselves, combined with the launching of