The Battle Hostile_encounter of Cer was a military campaign Military_operation fought Hostile_encounter between Austria-Hungary and Serbia in August 1914 , starting Process_start three weeks into the Serbian Campaign Military_operation , the initial military action of the First World War Hostile_encounter .

It took place Process_start around Cer Mountain and several surrounding Surrounding villages , as well as the town of Šabac .

The battle Hostile_encounter , part of the first Austro-Hungarian invasion Attack of Serbia , began Process_start on the night of 15 August when elements of the Serbian 1st Combined Cause_to_amalgamate Division encountered Austro-Hungarian outposts that had been established Creating on the slopes of Cer Mountain earlier in the invasion Attack .