 At dawn on 29 June , the rebels attacked the Ustaše in a village on the Mostar – Nevesinje road . Prohaska demanded help from Mostar , and planned to send a force from Nevesinje to assist . From Mostar , a company of the 21st Battalion was despatched to relieve the Ustaše , who had managed to hold off the rebels . The Home Guard company then took over the post from the Ustaše . The same day , two new battalions arrived in Mostar , the 23rd Battalion from <unk> and the 15th Battalion from <unk> . These reinforcements arrived just as Prpić received confirmation that Avtovac had been captured by the rebels . The remaining small garrison in Gacko , consisting of only 20 gendarmes and 30 Ustaše , were holding out but expecting more attacks by the rebels . In the morning , the attack by elements of the 10th Battalion stalled until the battalion commander , Lieutenant Colonel <unk> <unk> , personally took command of the operation , clearing the way for the Italians . The promised Italian intervention commenced about midday , and about 100 trucks of Italian soldiers arrived in Gacko about 17 : 00 . As they had passed through Avtovac , the rebels had left the town and withdrawn to villages to the east . About 18 : 00 , the 10th Battalion relieved the besieged gendarmes in the village schoolhouse . ZNDH aircraft from Mostar airfield flew reconnaissance sorties over the area and dropped leaflets over Stolac , Stepen , Avtovac , Gacko and Plužine . 
