The 3rd Army was formed in August 1914 as part of Austria-Hungary's mobilization following its declaration of war on Serbia and Russia, carrying out the prewar plans for the formation of six field armies. Just as all Austro-Hungarian field armies, it consisted of a headquarters and several corps, along with some unattached units. The 3rd Army initially consisted of the XI and XIV Corps, based in Lemberg (modern day Lviv, Ukraine), and Innsbruck, respectively. In addition there were several divisions that were attached directly to army headquarters. It was placed under the overall command of "General der Kavallerie" Rudolf Ritter von Brudermann. Early on in the war the formation took part in the Battle of Galicia in the northeastern part of the Dual Monarchy, where it was part of the Austro-Hungarian force advancing from Lemberg towards the Russian Southwestern Front's positions. On 25 August 1914, they received word of advancing Russian forces near Zlota Lipa river and 3rd Army was ordered to engage them. The clash began on August 26, with what the Austrians believed were small Russian units, but turned out to be eight corps. It was not long before they were forced to retreat, reaching Lemberg on August 27. Although 3rd Army had the time to form a defensive line near the Gnila Lipa river, the advancing Russians outnumbered Bruderman's army three to one and drove them back on August 30, before seizing Lemberg itself in early September. Thus the Austro-Hungarian line had to retreat back to the Carpathians, losing the country's territory east of the mountain range to the Russians.