 The Prohaska group deployed with one company on the road , and elements of the 17th Battalion and 70 Ustaše on the left flank . Their attack commenced about 10 : 00 , and although they faced strong resistance from the rebels , aided by <unk> and bombing by ZNDH aircraft , they reached villages on the outskirts of Nevesinje after fighting that lasted until dawn on 28 June . One Home Guard battalion halted and took up a defensive stance , and the commander was threatened with dismissal by Prpić before he resumed the attack . Francetić 's Ustaše unit also faced heavy fighting , and had to call for ammunition resupply on two occasions . One of the resupply vehicles was ambushed by rebels between Stolac and Berkovići , and some ammunition was finally delivered by passenger car during the night . Elsewhere , rebels attacked Gacko and Avtovac , and one ZNDH aircraft was shot down by rebel machine gun fire near Avtovac . That night , Prpić telephoned Kvaternik and advised him that the imposition of martial law was necessary to restore order to Herzegovina . Army Chief of Staff General Vladimir Laxa was immediately appointed by Pavelić to control both Hum and Dubrava counties , which incorporated much of eastern Herzegovina . 
