Battle of the Niemen River The Battle of the Niemen River was the second - greatest battle of the Polish - Soviet War . It took place near the middle Neman River between the cities of Suwałki , Grodno and Białystok . After having suffered almost complete defeat in the Battle of Warsaw ( August 1920 ) , Mikhail Tukhachevski ' s Red Army forces tried to establish a defensive line , against Józef Piłsudski ' s counter - attacking Polish Army , running northward from the Polish - Lithuanian border to Polesie , and centering on Grodno . Between September 15 and September 25 , 1920 , the Poles outflanked the Soviets , once again defeating them . After the mid - October Battle of the Szczara River , the Polish Army had reached the Tarnopol - Dubno - Minsk - Drisa line . Although this part of the conflict is usually referred to as a battle both in Polish and Russian historiography , some historians argue that it was more of a military operation with a series of battles fought often several hundred kilometres apart . Prelude . Following the Battle of Warsaw in mid - August , the armies in the centre of the Russian front fell into chaos . Mikhail Tukhachevsky ordered a general retreat toward the Bug River , but by then he had lost contact with most of his forces near Warsaw , and all the Bolshevist plans had been thrown into disarray by communication failures . Russian armies retreated in a disorganised fashion , with entire divisions panicking and disintegrating . The Red Army ' s defeat was so great and unexpected that , at the instigation of Piłsudski ' s detractors , the Battle of Warsaw is often referred to in Poland as the " Miracle at the Vistula " . Previously unknown documents from Polish Central Military Archive found in 2004 proved that the successful breaking of Red Army radio communications cipher s by Polish cryptographers played a great role in the victory . Although successful , the Polish counter - attack in the battle of Warsaw created an awkward situation for Polish commander in chief Józef Piłsudski . Most of his forces were facing north while Russian heartland was located east of the front rather than north . Because of that , the Polish Army needed some time to reorganise and regroup before a new offensive could be mounted . The Russian commanding officer Mikhail Tukhachevsky took this as an opportunity to establish a new defensive line along the Niemen River , initially safe from Polish forces . The new Soviet line ran from the Russian - Lithuanian demarcation line in the north , to the dense forests and swamps of Polesie , with the city of Grodno ( modern Hrodna , Belarus ) as a pivot . Opposing forces . Both the Polish Army and the opposing Red Army suffered heavy casualties in the course of war , and especially during the Russian summer offensive of 1920 . Moreover , both opposing armies were still in the phase of organisation . By August , the Poles mobilised almost 1 million men , which allowed them to reinforce most front - line units to approximately 50 - 60 % of their nominal strength . Out of that number almost 350 000 were in active service on the eastern front , while the rest served in other units or were still training . The Polish brigades and divisions were usually ill - equipped , but were commanded by experienced officers , veterans of the Great War and the subsequent Polish - Ukrainian War . Moreover , with fresh forces arriving to the front almost every week the reserves of the Polish C - i - C were sufficient for waging an offensive war . The Red Army suffered heavy casualties in the Battle of Warsaw in August and lacked organisation . Although the reserves of fresh , untrained recruits were almost unlimited , the Russian units lacked experienced officers . Also , in the course of the war the Soviet forces lost large parts of their artillery , which was usually used on the battlefield as a last stand against the assaulting enemy . This tactic allowed the Poles to outgun their enemies . Also , the Russian air forces were almost non - existent while the Polish Army could use its few aeroplanes to successfully disrupt enemy moves and conduct intelligence operations . The Red Army was organised in several fronts . The Western Front facing the Poles had more than 700 , 000 soldiers in August . However , a large part of its forces were either taken prisoner of war by the Poles , interned in East Prussia or routed . After the arrival of 68 , 000 reinforcements in August and additional 20 , 500 in September , the forces of Tukhachevsky reached approximately 20 to 40 % of their nominal strength . However , both the morale and the reinforcement abilities of the Russian troops were seriously harassed . Polish Army . The order of battle of the Polish Army as after the reorganisation of September 11 . The position of units as of September 15 , 1920 . The armies and divisions are listed north to south . Plans of both sides . Russian headquarters seriously overestimated its own forces . Sergey Kamenev ordered Tukhachevsky to mount an all - out counter - offensive as soon as the reorganisation of Russian forces was complete . By August 26 the Russians manned the Neman - Shchara - Svislach line with rump forces to escape the disaster at Warsaw . However , fresh reinforcements from mainland Russia were arriving on a daily basis and by mid - September Tukhachevski managed to recreate most divisions lost in mid - August . His forces quickly rose to over 73 . 000 soldiers and 220 pieces of artillery . Following Kamenev ' s orders , Tukhachevsky planned an offensive of three armies : the 3rd ( six divisions under Vladimir Lazarevich ) , 15th ( four divisions under Avgust Ivanovich Kork ) and 16th ( four divisions under Nikolai Sollogub ) . The Russian forces were to sweep southwards , retaking the Brest Fortress and Białystok , with the final objective being the city of Lublin . There the Russians could expect reinforcements from other Russian units operating south of the Pinsk Marshes in the Ukraine , as well as experienced troops that could be pulled back from other fronts of the Russian Civil War . At the same time Józef Piłsudski ' s main objective was to reorganise his forces and break through the enemy lines along the Neman before Russian defences stiffen , thus disrupting any attempts at enemy counter - attack . On September 10 , during a staff meeting with his generals , Piłsudski proposed a plan of a major operation near Neman and Shchara rivers . Two Polish armies ( 2nd under Gen . Edward Rydz and 4th under Gen . Leonard Skierski ) were to tie down main Russian forces by a frontal attack aimed at Grodno and Wołkowysk ( modern Vaŭkavysk , Belarus ) . Simultaneously , a strong force detached from the 2nd Army was to outflank the Russians from the north , through a strip of land between Sejny and Druskienniki ( modern Druskininkai ) occupied by Lithuanian forces and attack the Russian army from behind , in the vicinity of Lida . In the south , the 4th Army was to assault Wołkowysk and prepare to close the encirclement .