 The 2 / 1st Infantry Battalion began its advance on schedule at 0900 , but the lead platoon came under heavy machine gun fire from Post 54 , and Italian artillery knocked out the supporting mortars . The 3rd Regiment Royal Horse Artillery engaged the Italian guns and the platoon withdrew . Colonel Eather then organised a formal attack on Post 54 for 1330 , following a bombardment of the post by artillery and mortars . The Italian guns were silenced when an Australian shell detonated a nearby ammunition dump . The Australians then captured the post . About a third of its defenders had been killed in the fighting . The remaining 66 surrendered . This prompted a general collapse of the Italian position in the north . Posts 56 and 61 surrendered without a fight and white flags were raised over Posts 58 , 60 , 63 and 65 , and the gun positions near Post 58 . By nightfall , Eather 's men had advanced as far as Post 69 and only the fourteen northernmost posts still held out in the Gerfan sector . 
