 By 24 November , Potiorek was predicting that Serbia would be defeated within a matter of days and appointed Stjepan <unk> to be the country 's governor once it was occupied . The Austro @-@ Hungarians made further gains on 25 November , forcing the Serbian Army from Čovka and Vrače Brdo with an intense artillery bombardment . On 26 November , they attempted to cross the Kolubara at its junction with the Sava River and managed to do so in their initial attack . The Serbs soon counterattacked and forced the invaders back , inflicting 50 percent casualties on the Austro @-@ Hungarians and causing their offensive to grind to a halt . On 27 November , the Serbian Army attacked Čovka and Vrače Brdo and succeeded in forcing the Austro @-@ Hungarians out . 
