The first battle of Warsaw is sometimes used as an alternative name for the battle of the Vistula River (28 September-30 October 1914), an unsuccessful German invasion of south west Poland in the autumn of 1914. However, it is also used for the second part of that wider battle, the main Russian counterattack from Warsaw.
By 12 October General Mackensen with four divisions was within twelve miles of Warsaw. At the start of the wider battle the Russians had a single army in Warsaw, the Second, while the Fifth Army was moving to the city from the Carpathians.
Outnumbered by three to one, the Germans maintained their offensive for another five days, but on 17 October Hindenburg and Ludendorff were forced to order the retreat. The next day the German Ninth Army began a retreat back towards Silesia.
The Russian pursuit began on 19 October, marking the start of the first battle of Warsaw. The German retreat was skilfully managed. As the German armies advanced they had prepared for a possible retreat, placing explosives on key bridges. Now those bridges were blown, holding up the Russian pursuit. By 26 October the Germans had retreated sixty miles, and by the end of the month they had returned to their starting point. The entire campaign had cost them 40,000 casualties, and left Silesia vulnerable to a Russian invasion.