The Battle of the Vistula River, also known as the Battle of Warsaw, was a Russian victory against the German Empire and Austria-Hungary on the Eastern Front during the First World War.
By mid-September 1914 the Russians were driving the Austro-Hungarian Army deep into Galicia, threatening Kraków, and the Austro-Hungarian invasion of Serbia was floundering. The armies that the Russian commander Grand Duke Nicholas was assembling in 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 their Eastern Front the Germans had only one army, the Eighth, which was in East Prussia. It already had mauled two Russian armies at Tannenberg and at the First Battle of the Masurian Lakes. To support the reeling Austro-Hungarian Armies, OHL (Oberste Heeresleitung, German supreme headquarters) formed a new German Ninth Army in Silesia, to be commanded by General Richard von Schubert, with Erich Ludendorff, transferred from Eighth army, as chief of staff. Ludendorff quickly evaluated the situation in Silesia and convinced the new commander at OHL, Erich von Falkenhayn, to strengthen the Ninth Army and also to make Paul von Hindenburg commander of both German armies in the east.
By the end of September, Ninth Army, with headquarters in Breslau, consisted of the XVII, XX, XI, Guard Reserve Corps, Graf von Bredow's Landwehr Division, 8th Cavalry Division, and the 35th Reserve Division, with Woyrsch's Landwehr Corps linking the German Army with the Austro-Hungarian forces on the right. According to Prit Buttar, "Several Siberian divisions were now gathered around Warsaw, and it seemed likely that these would march southwest to support a westerly drive by the forces of Southwest Front. In order to oppose this, Conrad and Ludendorff agreed, the k.