The forces under the command of Falkenhayn executed a certain number of attack tests in the passes of Carpathians in order to test the weak points of the defense. On 10 November, after a few weeks of concentration of their best troops, the elite unit Alpenkorps, Germans attacked in front of the Vulcan Pass, so that they pushed back the Romanian defenders into the mountains. On 26 November, fighting took to the hills. In the mountains, the snowfall started and soon the military operations stopped. The German 9th Army advanced in other sectors of the battle front, attacking all of the passes of the Southern Carpathians, Romanians being forced to retreat constantly, whenever their lines of supply became more and more stretched.