On 5 November 1914, the Austro-Hungarian 5th and 6th Armies entered Serbia, pushing the Serbians back to the Kolubara line. Between the 16–22 November the Austro-Hungarians launched a third series of assaults on Serbian defenses on the Kolubara line, with the objective of seizing the strategically important town of Lazarevac. This would provide access to the railway and enable re-entry to Belgrade, outflanking the Serbian forces who were guarding the road to Belgrade further south. The Serbians were successfully pushed back, with the 5th and 6th Armies advancing deeper into Serbia. Despite fierce resistance and freezing weather conditions, the Austrians managed to finally force the Serbians out of Belgrade on the 29 November. On 1 December, they occupied Belgrade, believing that they would soon be occupying the entire country.