[1][2][3] 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.

[6] By 12 September, three-fourths of the distance between the Transylvanian border and the vital junction of Hátszeg (Hațeg) had been covered by the Romanians.

[3] 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.

At the beginning of September, the Romanian units in the area comprised the bulk of General Culcer's 1st Army: the 2nd, 11th and 12th Divisions.

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".

The Central Powers, disposing of an exceedingly strong concentration of mountain artillery and howitzers, delivered a frontal attack whose main weight was directed against the Romanian left center, around Mount Branu.

The original Romanian front at Nagybár ran from north to south, but on 19 September the line extended from east to west, between Mount Tulisini (Tulișa) and Petrozsény (Petroșani).