Coupled with a successful German and Austro-Hungarian counterattack which started in mid-September, the Romanian Army was eventually forced to retreat back to the Carpathians by mid-October.

Officers from the Romanian General Staff began the planning of a potential invasion of Hungary as early as 1913, following Romania's successful expansion at Bulgaria's expense during the Second Balkan War.

A draft document appeared in the summer of 1914, but Bulgaria's entry into the war on the side of the Central Powers in 1915 forced a major revision of the initial campaign plan.

Hypothesis Z called for the Romanian occupation of Transylvania and Banat, using three armies (1st, 2nd and Northern) which amounted to a total of 420,000 soldiers (75% of Romania's field force).

The 11th Infantry Division (General Ioan Muică [ro]) subsequently continued its advance Northwards, stopping 15 mi (24 km) South of Hátszeg (Hațeg).

Sixty-five miles to the East, Culcer's main force — the Olt-Lotru Group — entered the Turnu Roșu Pass and advanced towards Nagyszeben (Sibiu).

The Lotru Group reached Nagytalmács (Tălmaciu) on 29 August, and subsequently regrouped there before advancing a few more miles North towards Nagyszeben (Sibiu), stopping at Vesztén (Șelimbăr).

The Austrian commander at Nagyszeben (Sibiu), Colonel Arnold Barwick, sent an armored train to investigate, but this was set ablaze by the Romanians and rendered unserviceable.

The Romanians began their retreat through the pass in earnest on the 28th, through the bullets of the Alpine Corps and German barricades of dead horses and wagons, which had to be blasted away by artillery.

In response, Falkenhayn deployed the German 301st Division under General Johannes von Busse, which arrived in the region on the 28th, linking up with the 2nd Austro-Hungarian Mountain Brigade.

At the Alsótömös (Timișu de Jos), the Székelys' 1st Battalion, supported by an armored train, held its ground for an entire day, only being pushed back on the night of 28 August.

[12] The 2nd Army crossed the Olt River at its Southern part on 15 September, then attacked on a line from Fogaras (Făgăraș) to Homoród (Homorod), threatening the juncture between two German units.

Crăiniceanu's timidity stemmed partly from the fact that the Romanian General Staff had recently stripped his army of half of its strength, shifting three of its divisions to the Dobruja front.

[14] The 2nd Army started advancing again on 29 September, pushing back the Honvéd 2nd Cavalry Division and reaching Székelykeresztúr (Cristuru Secuiesc), a dozen miles from Segesvár (Sighișoara).

The Romanians retreated from Brassó (Brașov) during the night of 8/9 October, amidst German machine gun fire from vantage points in and around the city.

The two regiments of the Romanian 15th Brigade of the 8th Division marched through the Oituz Pass [ro] and reached Kézdivásárhely (Târgu Secuiesc) on 29 August, in time to destroy the last train leaving from the town.

Hungarians of the exhausted and under-manned 19th Brigade, under Colonel Szabo, offered little resistance, its engineers managing to blow up the crucial Karakó railroad viaduct near Palanca.

The two Romanian brigades of the 7th Division failed to pursue the Hungarians west of the Olt, as they stopped at Csíkszereda (Miercurea Ciuc) and dug in on the eastern side of the river.

Further north, the Austrians gave up Bélbor (Bilbor) when they ran out of ammunition, and managed to keep the Romanians East of Borszék (Borsec) as well as engaging them successfully in the Neagra Șarului Valley.

The 14th Division captured Gyergyószentmiklós (Gheorgheni) from Colonel Kornél Bernátzky's 16th Honvéd Brigade, reaching the eastern edges of the salt-mining town of Parajd (Praid)on 11 September.

The 14th Divisions's 22nd Brigade emerged from the Gyergyó (Giurgeu) Mountains and began advancing slowly along both banks of the river Maros (Mureș) towards Maroshévíz (Toplița).

The exhausted Austro-Hungarian 1st Army under General Arthur Arz von Straussenburg moved slowly, giving the Romanians an uncontested run to the border.

On 8 and 9 October, as the Battle of Brassó was drawing to a close, two Romanian units retreated from the north and northwest and formed a defensive perimeter around Kézdivásárhely.

The Austrians moved mountain brigades from the Italian Front to Transylvania, while the Germans redeployed the Alpine Corps from Verdun and the 76th Reserve Division from Riga.

[49] On 28 August, the Austrians - unable to muster resistance at any level - reluctantly agreed to a unified Central Powers command for the Eastern Front.

During September the Central Powers ratified agreements making the German emperor their supreme commander, a concession which gave Hindenburg and Ludendorff control over the Austro-Hungarian, Bulgarian and Ottoman armies.

[15] When the North Army was ordered to retreat in early October, the exhausted Austrians moved slowly and gave their enemies an uncontested run to the border.

Thus, judging by the current borders of the region, the battle would have actually ended on 25 October, when the fighting for Predeal ceased and the town was seized by the Central Powers.

Zottu's name was found on a list of people, Lista lui Günther [ro], who were allegedly bought by the head of a major German oil company operating in Romania.

An officer of the general staff found him unqualified, while Alexandru Marghiloman, the leader of the Conservative Party, had this to say about his appointment: "How is that possible?...Do not make such a mistake; he has been confused all his life, and he is absolutely worn out.".