2nd Army ( Russian Empire ) The Russian 2nd Army was an army level command of the Imperial Russian Army in World War I . It was formed just prior to the outbreak of hostilities and was mobilized in August 1914 . The army was effectively dissolved on 30 August 1914 following its near destruction at the Battle of Tannenberg and it was never raised again . History . Prior to the outbreak of war , in which Russia would likely have to face both Germany and Austria - Hungary , the 2nd Army had been intended to be a reserve formation , held back until either of the formations engaged against Germany and Austria - Hungary required reinforcements . Following the outbreak of war it was mobilised in early August and placed under the command of General Alexander Samsonov . Under pressure from their ally France , who was facing a powerful German invasion force in the west , it was decided that the 2nd Army would join the 1st Army as part of General Yakov Zhilinskiy ' s Northwestern Front where it would participate in the upcoming invasion of East Prussia . The combination of the 1st and 2nd Armies would have a fatal flaw ; Samsonov and Paul von Rennenkampf ( commander of the 1st Army ) shared an antagonistic and hostile relationship dating back to 1905 . Eastern front . Between 7 – 9 August 1914 first the 1st and then the 2nd Army crossed the border into East Prussia , meeting little to no resistance . The 1st Army would engage the Germans at the battles of Stallupönen and Gumbinnen while the 2nd Army had remained unengaged , advancing to the south of the 1st Army . Battle of Tannenberg . Following the failed German counterattack at the Battle of Gumbinnen and the subsequent German withdrawal , the 1st Army did not press on , allowing the 2nd Army to catch up but due to a breakdown in communication ( partly due to the animosity of the two commanders ) the 2nd Army was not made aware of this and so it continued to march on , a fatal move that would eventually expose the right flank of the 2nd Army . The 2nd Army was also experiencing severe supply shortages and along with the 1st Army a worsening communication situation as both armies had outrun their secure telegraph lines , were short of experienced telegraph operators and lacked cryptographic equipment . The result was that the Russians were now broadcasting their orders on unsecure lines , which were being intercepted and translated by German operators . The 2nd Army was to continue its advance south of the 1st Army and German 8th Army before swinging north towards its objective of Seeburg , but with little to no effective communication there was little coordination between the two armies . While sluggish due to supply shortages , poor logistics , and misuse of railway lines , the 2nd Army ' s advance was relatively unopposed until 22 August when it encountered German forces all along its front . A number of successful thrusts were conducted , pushing the Germans back . On 23 August they succeeded in driving the German XX Corps back to a defensive line . A second push against the XX Corps on the 24th failed but the Germans withdrew to avoid being cutoff . Samsonov saw this as a perfect opportunity to pursue and cut the XX Corps off and so began moving the 2nd Army in a northwesterly direction , changing his direction of attack and not informing Rennenkampf in the process . Seeing this opportunity and feeling safe on his flanks , he transferred the bulk of his force to the northwest , leaving a single corps , VI Russian Corps , to simultaneously hold the right flank and swing north to the objective of Seeburg and a single corps , I Russian Corps , to hold the left flank . Unbeknown to Samsonov , the German command , who had been receiving intercepted Russian orders involving troop movements , had already shifted forces to the south to check his advance and when further orders were intercepted with news that he had changed his direction , German forces were able to adjust their positions and threaten the now exposed left and right flanks of the 2nd Army . With no communication between the two Russian armies , unsafe broadcasting of orders and the decision to change his direction of attack , the 2nd Army would find itself outflanked and cutoff from mutual support from the 1st Army . On 26 August the 1st Army approached Königsberg unopposed as the German forces had identified the 2nd Army as a more immediate threat and had withdrawn to the south in order to engage it . The VI Corps , whom Samsonov had left on its own to seize the objective of Seeburg , was met by the German XVII Corps around Seeburg and Bischofstein and was routed , exposing the 2nd Army ' s right flank and supply lines . Unaware that his right flank was now exposed , Samsonov pressed the 2nd Army on and repeatedly engaged the XX Corps . On the 27th the German I Corps engaged the Russian I Corps on the 2nd Army ' s left flank and threw it back . Samsonov diverted the Russian XIII Corps , which had been leading the northwestern thrust , to the southwest in an attempt to reinforce the 2nd Army ' s left flank but the decision came too late and like the right flank , the left flank was now exposed . Late on the 28th Samsonov finally realised the grave situation the 2nd Army was in with both flanks exposed . With the centre also facing critical supply shortages the assault was halted before an order to retreat to the southeast was given . Samsonov then requested that the 1st Army break - off its assault on Königsberg and assist the 2nd Army by covering its retreat . The order to retreat and the request for assistance came too late to rescue the 2nd Army . The German I Corps had proceeded to move due east after breaking through the 2nd Army ' s left flank and had met the German XVII Corps that had continued in a southwesterly direction after breaking through the 2nd Army ' s right flank , cutting off the 2nd Army ' s route of retreat and pocketing it around Tannenberg . Throughout the 29th German artillery pounded the Tannenberg pocket and at some point on the 29th Samsonov shot himself . The shattered remnants of the 2nd Army surrendered on 30 August with some 90 , 000 Russian POWs being captured and with them the Russian 2nd Army ceased to exist . The 2nd Army would not be raised again for the duration of Russia ' s participation in the war . Commanders . The 2nd Army only had one commander from its mobilisation until its destruction on 30 August 1914 .