three infantry companies, a machine gun platoon and a communications section, while battalions of the Ustaše Militia consisted of a headquarters, three companies and a motorised section. Even after the establishment of NDH authorities in eastern Herzegovina, Italian forces maintained their presence in the region. The 55th Regiment of the 32nd Infantry Division Marche remained garrisoned in Trebinje, with the 56th Regiment based in Mostar. The 49th MVSN Legion (Blackshirts) were also stationed in Bileća. The Italians maintained a troop presence in Nevesinje until 17 June, and conducted almost daily motorised patrols throughout eastern Herzegovina. The NDH authorities established new administrative sub-divisions, organising the state into counties () and then districts (). Eastern Herzegovina was covered by the counties of Hum and Dubrava. Hum County included the districts of Mostar and Nevesinje, and Dubrava County included the districts of Bileća, Gacko, Stolac, Ravno and Trebinje. The Župan (county prefect) of Hum was Josip Trajer with his seat in Mostar, and the Župan of Dubrava was Ante Buć, based in Dubrovnik. According to the Yugoslav census of 1931, the population of eastern Herzegovina comprised 4 per cent Croats, 28 per cent Muslims, and 68 per cent Serbs. According to Professor Jozo Tomasevich, the estimated population of the districts of Bileća, Gacko and Nevesinje was only around 1.1 per cent Croat, so in those areas nearly all the NDH government appointments and local Ustaše units were staffed by Muslims, an ethnic group that made up about 23.7 per cent of the local population. The poor Muslim peasants of eastern Herzegovina largely sided with the Ustaše. The NDH government immediately tried to strengthen their position by vilifying the Serbs, who, according to Tomasevich, comprised around 75 per cent of the population. Prelude The Ustaše began to impose the new laws on the Serb population of the NDH. On 28 May, a group of ten young Ustaše students from the University of Zagreb arrived in Trebinje and began removing signs written in the Cyrillic script used by Serbs. On 1 June, in several towns and villages in eastern Herzegovina, Serbs were shot and businesses belonging to Serb merchants and others were seized. On that day, the Ustaše students in Trebinje shot nine Serbs and arrested another fifteen, apparently due to their links to the inter-war Chetnik Association. Differences began to appear between the brutal treatment of Serbs by the Ustaše and the more careful