On the night of 13/14 October 1915, Combined squad of the Belgrade's Defense, held the line Avala-Zuce, defending it from the joint Austro-Hungarian and German offensive. Austro-Hungarian 9th Hill brigade of the 59th Division took the front rim of Avala on 16 October, with an assignment to push Serbian forces from the mountain. Austro-Hungarians were reinforced with one German half-battalion. However, one Serbian battalion successfully defended the top of Avala against the Austro-Hungarian battalions of the 49th and 84th regiments, aided by the 204th German reserve infantry regiment. On the same day, the command of the Belgrade's Defense ordered the retreat to the new positions so on 17 October occupational forces reached the southern section of Avala, conquering the entire mountain. Their soldiers then buried Serbian combatants who were killed in action. In the valley, below Žrnov, on the grave of one of them, they placed a wooden cross with the inscription in German: "One unknown Serbian soldier".