 The offensive 's initial success served to greatly enhanced the morale of Serbian troops , just as Putnik had wanted . Significantly weakened , the Austro @-@ Hungarians did not have time to recover before the offensive resumed the following morning and they were forced into retreat by the end of the day . On 6 December , the British ambassador to Serbia informed the British Government that the Serb offensive was " progressing brilliantly " . That day , the Serbian Army had broken the Austro @-@ Hungarians at their centre and on their right flank . Outmanoeuvred , the Austro @-@ Hungarians were forced into a full retreat , abandoning their weapons and equipment as they went . Meanwhile , the Austro @-@ Hungarians attempted to consolidate control around Belgrade . On 7 December , they attacked the right flank of the Serbian Army in the city 's outskirts . 
