Battle of Tannenberg The Battle of Tannenberg was an engagement between the Russian and the German Empire s in the first days of World War I . It was fought by the Russian Second Army against the German Eighth Army between 26 August and 30 August 1914 . The battle resulted in the almost complete destruction of the Russian Second Army . A series of follow - up battles destroyed the majority of the First Army as well , and kept the Russians off - balance until the spring of 1915 . The battle is notable particularly for a number of rapid movements of complete German corps by train , allowing a single German army to concentrate its forces against each Russian army in turn . Although the battle actually took place close to Allenstein ( Olsztyn ) , General Erich Ludendorff ' s aide , Colonel Max Hoffmann , suggested naming it after Tannenberg , in the interest of Pan - German ideology , to counter the defeat of the Teutonic Knights at the Battle of Grunwald ( Tannenberg ) in 1410 by the Poles , Lithuanians and Tatars . As pointed out by the Australian historian Christopher Clark , the actual Tannenberg is some to the west , and there was no intrinsic reason — other than the historical battle and its emotive resonance in the narrative of German and Slavic nationalism — to give its name to the 1914 battle . Background . The Allied battle plan prior to the war had been based on France and the United Kingdom halting the German armies in the West while the huge Russian armies could be organized and brought to the Eastern front . The numbers were overwhelming ; in perhaps as little as a month , the Russians could field around ten complete armies , more men than the Germans could muster on both fronts put together . At Tannenberg the actual ratio of Russian to German troops was 29 to 16 . Frustrating this plan was the Russians ' lack of a good quality railroad network . Additionally , Russian trains operated on a different rail gauge to Germany , meaning that unless the Russians acquired German railroad engines and cars , their armies could only be transported by rail as far as the German border . The presence of the armies of Austria - Hungary to the south as well as initially those of Japan to the east limited Russia ' s involvement in the beginning ( however , Japan declared war on Germany on 23 August 1914 ) . Nevertheless , the Russians considered the Germans to be their primary threat , and planned to use limited forces to quickly seize East Prussia . The Germans likewise considered the Russians to be their primary threat . The entire Schlieffen Plan was based on the idea of defeating France as quickly as possible , and then transporting their armies by train to the eastern front . This allowed the Germans to garrison Prussia fairly lightly with a single army , the Eighth , while the German Ninth Army was stationed in central Germany to reinforce either front . There was little allowance for anything other than a delaying action while the outcome in the west was decided . In order to delay the Russian forces as long as possible , the entire area around Königsberg ( now Kaliningrad ) , near the Russian border , was heavily fortified with a long series of fieldworks . Just prior to the opening of the war , the situation developed largely as prewar planning had expected . The German Eighth Army was in place southwest of Königsberg , while the two available Russian armies were located to the east ( the First Army ) and south ( the Second Army ) ; the latter in what was known as the " Polish Salient " . Russian battle plans called for an immediate advance westward by the Russian First Army under General Pavel von Rennenkampf into East Prussia , with Königsberg as the initial objective . The Russian Second Army under General Alexander Samsonov was to initially move westward around the Masurian Lakes and then swing north over a hilly area to cut off the Germans , who would by this point be forced into defending the area around Königsberg . If executed successfully , the Germans would be surrounded . Prelude . During the first weeks of the war , the situation developed largely according to the German plan . The Germans had moved up about half of the units of the Eighth Army , reinforced by small groups of the Königsberg garrison , to positions east of the city near the border . The Battle of Stallupönen , a small engagement by the German I Corps under Hermann von François , was successful . Nevertheless , the German theater commander , General Maximilian von Prittwitz , ordered a withdrawal towards Gumbinnen . A counterattack planned for 20 August had a fair chance of succeeding but François attacked prematurely , before Mackensen ' s XVII Corps and Below ' s I Reserve Corps arrived at their positions . Thus alerted to German intentions , the Russians moved their heavy artillery up and were able to turn the attack into a disordered retreat . The Battle of Gumbinnen forced the Germans , in many cases via rail , to take positions south of Königsberg . Concerned by the defeat at Gumbinnen and the continued advance of the Russian Second Army from the south , Prittwitz ordered a retreat to the Vistula , effectively abandoning East Prussia . When he heard of this , Helmuth von Moltke , the German Army Chief of Staff , recalled Prittwitz and his deputy to Berlin . They were replaced by Paul von Hindenburg , who was called out of retirement , with Erich Ludendorff as his chief of staff . Things were not quite as dire as they seemed to the German commanders in Berlin . The two Russian commanders had disliked each other since Samsonov had publicly complained about Rennenkampf ' s behavior at the Battle of Mukden in 1905 . Although the common belief that the two generals had come to blows at a railway station has proved to be incorrect , Rennenkampf would not be inclined to help Samsonov except under dire circumstances . Additionally , Samsonov ' s Second Army was having serious problems moving forward due to poor supply preparations , and unknown to him , Rennenkampf had decided to delay the First Army ' s advance to regroup after Gumbinnen , believing the Germans were preparing another attack . Nevertheless , the scale of the forces deployed still meant the Russians had the upper hand . As they were currently deployed , the German Eighth Army could not even cover the front along Samsonov ' s line of march , leaving Samsonov ' s left wing free to advance without opposition . Unless troops from the Königsberg area ( I , XVII and I Reserve Corps ) , could be moved to check this advance , the Germans were in serious danger of being cut off . German consolidation of Eighth Army . Colonel Max Hoffmann , Prittwitz ' s deputy chief of operations , was well aware of the animosity between the Russian generals , and what it would likely mean for their plans . Guessing that the Russian armies would continue to operate separately , Hoffmann proposed moving almost all German forces not already in Königsberg ' s eastern defense line to the southwest , moving I Corps by train to the left of Samsonov ' s line , a distance of over . The XVII Corps and I Reserve Corps , at the time south of I Corps , would be readied for a move further south to face the Russian VI Corps on Samsonov ' s right flank . The German 1st Cavalry Division would remain as a screen just south of the eastern edge of the Königsberg defenses , facing Rennenkampf ' s First Army . The eastern portion of the Königsberg defenses was the only part that was fully manned , while the approaches from the south were entirely open . In theory , the plan was extremely risky . If the First Army turned to the southwest instead of advancing directly westward toward Königsberg , they would appear on the Eighth Army ' s extreme left flank , allowing for either a counterattack against the Eighth , or alternately turn north toward Königsberg from the undefended south . However , Hoffmann was convinced of the soundness of his plan , both because he was aware of the animosity between the Russian generals , and also because of the Russian habit of transmitting the next day ' s orders over unencrypted radio communications . It appears the Russians had outrun their secure telegraph landlines , and were short of trained wireless telegraph operators and cryptographic equipment . This forced them to transmit their messages in the clear , and these were easily intercepted and translated by the Germans . When Hindenburg and Ludendorff arrived on 23 August , they immediately stopped the retreat and put Hoffmann ' s plan into action . Since Prittwitz had already ordered the German troops to pull back via train , Ludendorff directed I Corps to alight near Deutsch - Eylau to cover the left flank of XX Corps , who had been in front of the Second Army since before the battle at Gumbinnen . Hoffmann had already issued similar orders , so little confusion resulted . The trap was being set . Ludendorff also learned at this point that von Moltke had decided to take three corps and a cavalry division from the Western front and redeploy them to East Prussia . Ludendorff protested that they would arrive too late to have any effect , while at the same time weakening the German offensive through Belgium against France . However , von Moltke considered East Prussia too politically important to lose , and ignored Ludendorff ' s protests . Later , this movement of German forces would be seen as the final undoing of the Schlieffen Plan that demanded a considerable preponderance of local forces in a rapid encirclement and destruction of the French armies east of Paris as they were driven onto the German anvil on the Franco - German border . Early phases of battle ( 23 August to 26 August ) . Starting on 22 August , Samsonov ' s forces had met the Germans all along their front , and had successfully pushed them back in several places . On the 23rd , they attacked the German XX Corps , which retreated to the Orlau - Frankenau line that night . The Russians followed , and on the 24th they met them again at Orlau - Frankenau , where the now - entrenched XX Corps temporarily stopped the Russian advance . Once again XX Corps retreated in order to avoid possible encirclement by superior forces . Undeterred , Samsonov saw this as a wonderful opportunity to cut this unit off completely , because , as far as he was aware , both of his flanks were unopposed . He ordered most of his units to the northwest , toward the Vistula , leaving only his VI Corps to continue north towards their original objective of Seeburg . Concerned about this possible flanking maneuver , Ludendorff issued an order to François ' now - deployed I Corps to initiate the attack on Samsonov ' s left wing at Usdau on 25 August . François rejected this direct order , stating there was no way to have the corps ready in time and that he wanted to wait until his artillery support was ready on 27 August . Ludendorff and Hoffmann would have none of this , and traveled to meet François to repeat the order in person . François agreed to commence the attack , but complained of a lack of artillery shells , telling his superiors that his troops would be obliged to charge with bayonets . On the way back from the meeting , Hoffmann received new radio intercepts . Rennenkampf ' s most recent orders stated the next day ' s offensive would continue due west , ignoring Samsonov , just as Hoffmann had hoped . No matter the outcome of the impending battle in the south , the Russian First Army would not be a serious concern . A second intercept of Samsonov ' s own plans made it clear that he would continue his own march northwest , having concluded that the Germans would continue to retreat in front of Tannenberg . Ludendorff and Hindenburg were doubtful that these intercepts were real , finding it difficult to believe that even one Russian commander would send his messages in the clear , let alone two . Nevertheless they were eventually convinced they were indeed real , and the plans were put into action . I Corps would open its attack on the Russian left flank on 25 August , while orders were sent to XVII Corps to move south and meet the Russian right flank as soon as possible . Given that the need for immediate action was no longer pressing , François once again demanded he be allowed to wait for his artillery supplies . Ludendorff and François began arguing , and eventually François delayed enough to allow the battle to open on 27 August as he had wished . The main battle ( 26 August to 30 August ) . The morning of the 26th opened with the First Russian Army advancing west towards Königsberg , meeting little resistance . The troops that were formerly directly in front of them had moved to the south , facing the Second Army ' s right flank . There was still time to close the gap between the Russian armies and thereby threaten the German movements , which by this point were being reported back to Russian headquarters . Nevertheless , on the night of the 25th , the Russian field commander sent orders for the First Army to continue directly west to Königsberg , orders that were once again intercepted by the Germans . Due to François ' delays , XVII German Corps opened the battle proper . They met the two separated divisions of VI Russian Corps near Seeburg and Bischofstein , turning them both back toward the border in disarray . The right flank of the Second Russian Army was now open . In the meantime , the Russian advance toward Tannenberg continued to be blocked by XX German Corps in front of them . Their only success were in the center , where XIII Russian Corps advanced toward Allenstein unopposed . François opened his own attack on the Russian left on the 27th , held by I Russian Corps . His artillery proved to be decisive , and by that night the Russians were falling back . In order to help stabilize the line , Samsonov ordered the seemingly successful XIII Corps to abandon Allenstein and turn southwest to help break through at Tannenberg . By the time this maneuver was complete , the bulk of the Russian Second Army were all in the Tannenberg area , consisting of the newly arrived XII , XV , and part of XXIII Corps . By the evening of 28 August , the full extent of the danger to the Russians was evident . Their I Corps on the left and VI Corps on the right were both retreating . Meanwhile the center was having serious supply problems and could no longer hope to maintain an offensive . Samsonov had no option but to order a retreat to the southeast and attempt to reorganize near the border . Meanwhile , he asked Rennenkampf to ignore Königsberg and turn southwest to help . It was too late . François by this time had advanced due east to form a line to the south of the Russians between Niedenburg and Willenburg , directly in their line of retreat . At the same time , XVII Corps in the north had moved southwest to meet him . The next day the Russian center met these troops on their way to regroup , and realized they were surrounded . A pocket formed east of Tannenberg , near Frogenau , and was pounded by artillery throughout 29 August . Attempts by the Russian First Army to come to their aid were also far too late to help . The German cavalry screen proved effective at delaying them , and by the time the battle was already over , their closest unit was still to the northwest of the initial contact between XVII German Corps and VI Russian Corps , perhaps as much as from the trapped Second Army . Other Russian units were scattered back along the line to Königsberg , leaving the First Army itself in a dangerously spread - out position . By the time the battle ended on 30 August , Samsonov ' s Second Army was destroyed , with 92 , 000 Russian troops captured , another 78 , 000 killed or wounded , and only 10 , 000 ( mostly from the retreating flanks ) escaping . The Germans suffered fewer than 20 , 000 casualties and captured over 500 guns . Sixty trains were required to transport captured Russian equipment to Germany . Rather than report the loss of his army to Tsar Nicholas II , Samsonov committed suicide by shooting himself in the head on 29 August 1914 . Aftermath . The German victory at Tannenberg was , according to the author David Stevenson , " a major victory but far from decisive " . It set the stage for the First Battle of the Masurian Lakes a week later , where the reinforced German Eighth Army now faced only the Russian First Army and forced it back over the prewar border . Russian forces would not again march on German soil until the end of World War II . Although Tannenberg did not produce the strategic results that Masurian Lakes later did ( forcing the Russians out of Germany for good ) , it was a tactical masterpiece , and bolstered the morale of the German troops while severely shaking that of the Russians . Unfortunately for the Germans , they could not take the initiative with either of these great victories . Firstly , because as soon as they pursued the Russians over the border they would be slowed by the narrower gauge rail network , and secondly because the Russians had won a similar victory against their ally Austria at Lwow , and German assistance was desperately needed . Ludendorff sent the official dispatch from Tannenberg , and the battle was named " Battle of Tannenberg " at the direct request of Hindenburg . He chose Tannenberg because of its historical significance ; it was the location where the Teutonic Knights were defeated by the joint forces of the Kingdom of Poland and the Grand Duchy of Lithuania at the Battle of Grunwald ( referred to in German as " Schlacht bei Tannenberg " — " Battle of Tannenberg " ) . Hindenburg and Ludendorff were both hailed as heroes , although Hoffmann was generally ignored by the press . Apparently not pleased by this , Hoffmann later gave tours of the area noting , " This is where the Field Marshal slept before the battle , this is where he slept after the battle , and this is where he slept during the battle . " However , Hindenburg countered by saying , " If the battle had gone badly , the name ' Hindenburg ' would have been reviled from one end of Germany to the other . " Post - war legacy . The battle is at the center of Aleksandr Solzhenitsyn ' s novel " August 1914 " . A German monument was completed in 1927 . However , it was blown up by the Germans during the retreat in January 1945 . Ludendorff would later revisit the battle site when naming his own political movement , the Tannenbergbund , formed in 1925 . The German film director Heinz Paul made a film " Tannenberg " about the battle , filmed in East Prussia in 1932 . Comparable historical battles . Hindenburg and Ludendorff ' s daring maneuvers to surprise and defeat in detail two enemy armies may be compared to a classic example such as the Battle of Austerlitz . However , the disastrous consequences of failing to defeat each enemy force in turn can be seen at the Battle of Waterloo .