[2][3][4] Given that this was a region of valuable coal mines which were vital for the Hungarian railways, this was the area where the first Central Powers counterattack against the Romanian invasion of Transylvania was launched.

Despite German support, the Austro-Hungarian commander of the 144th Infantry Brigade, Colonel Ludwig Berger, "inexplicably" ordered a retreat.

[5][6] German General Hermann von Staabs, the commander of the XXXIX Corps which had assumed responsibility on 8 September for operations in the southern region of Transylvania, reacted quickly to the Austrian withdrawal.

On the 9th, Major Radu R. Rosetti from the Romanian headquarters stated to General Andrei Zayonchkovski - the Russian commander in Dobruja - that the 2nd and 12th Divisions "were coming from Transylvania".

[8] The German-led Central Powers force disposed of an exceedingly strong concentration of howitzers and mountain guns, amounting to an overwhelming superiority in artillery.

[13] The Central Powers force left behind to mask the Vulcan and Szurdok passes thus remained mostly Austro-Hungarian, consisting of the 144th Brigade reinforced by two German battalions and two batteries.

[14] However, sympathetic ethnic-Romanians living in the region immediately made General Culcer's headquarters aware that the bulk of the Germans had pulled out of the area.

Based on General Edwin Sunkel's reports, von Falkenhayn decided that Nagyszeben (Sibiu/Hermannstadt) was the only location suitable for a decisive victory.

[16] On 25 September, the Romanian 11th Division attacked, by the end of the day managing to regain not only Petrozsény,[17][18] but the two mountain passes (Szurdok and Vulcan) as well.

[20][21] Colonel Berger, the local Austro-Hungarian commander, at first thought his forces could hold, but the exhausted miners collapsed, allowing the Romanians to reenter Petrozsény on the 25th.

[24] By 28 September, the Romanians had recovered ten miles of lost ground within the Hungarian frontier, driving the Austro-Hungarians and the Germans before them.

[31] Certain sources appear to be surprised by the Romanian success, that - after being overwhelmed by the artillery used against his forces during what was at the time General Falknehayn's main blow - Culcer was "even able" to make some headway against his opponents.