The armies that the Russian commander Grand Duke Nicholas was assembling in Congress Poland were still enlarging, including the arrival of crack troops from Siberia, freed by the Japanese declaration of war against Germany on 23 August.

Stavka (Russian supreme headquarters) intended for the forces assembled south of Warsaw—500,000 men and 2,400 guns—to march west to invade the German industrial area of Upper Silesia, which was almost undefended.

On 28 September, the Germans started their advance, while Dankl's First Army crossed the Vistula, reaching Bogoria on 1 October.

The Russian response was for Ruzsky to advance towards Kalisz, while Ivanov's Second, Fourth, Ninth, and Fifth Armies concentrated along the Vistula.

The Russian corps marching north to fill the gap moved along the east bank of the Vistula, which protected their left flanks.

[18] To guard the crossings for their Fourth and Ninth Armies, on the west bank of the Vistula the Russians deployed the 75th Reserve Division (Fourth Army) at Radom, as well as the group of General Delsalle, consisting of the Guard Rifle Brigade, 2nd Rifle Brigade and 80th Reserve Division, at Opatów-Klimontów.

As they advanced they improved the roads and bridges so they could support heavy artillery and adjusted the rails to the narrower European gauge.

[19] On 6 October, Dankl's First Army cavalry had reached Sandomierz, and though the Russians lost 7000 of General Delsalle's infantry killed or taken prisoner near Opatów, the remaining forces had withdrawn across the Vistula.

Their left flank, August von Mackensen's XVII Corps, continued to march north until it was 19 km (12 mi) from Warsaw.

General Nikolai Ruzsky, commander of the Russian Northwest Front, sent troops from Warsaw to attack XVII Corps on the German left flank.

Unlike the messages sent in the clear during the first weeks of the war, now they were in the new Russian code, which by the end of September had been broken by a German reserve officer, Professor Deubner.

The Russian Fourth Army was deployed with its XIV, XVII and Guards Corps along the lower San and Vistula.

Dankl's attack faltered, while the next day his eastern flank was threatened by Russian troops crossing the Vistula at Puławy.

[23] In any event, the Russians were able to bring enough men quickly over the river to force the Austro-Hungarians to retreat to a line 60 km (37 mi),to the west.

They portrayed the withdrawal as a strategic maneuver, and had succeeded in blocking an enemy advance into Germany for weeks, while their army was trying to win on the Western Front.

But they dissipated their advantage by indecision about their next move and confusion in their administrative arrangements [29] On 1 November, Hindenburg was given command of all of the German forces on the Eastern Front.

Mackensen was promoted as commander of the Ninth Army, the majority of which was deployed by rail to Thorn, so as to threaten the Russian northern flank.

Yet, for the Austro-Hungarian forces, in the words of Buttar, "All the gains of the October campaign were to be abandoned, and a new line would be held through the winter, running along the Carpathians and then to Krakow.

Historian Alexei Oleynikov estimated the losses of both sides at 150,000, highlighting that the central powers lost 50% of the offensive group, and the Russians only 32%.