Battle of Wilno ( 1939 ) The Battle of Wilno ( Vilnius , Vilna ) was fought during the Soviet invasion of Poland in 1939 ; it accompanied the larger German invasion . During 18 – 19 September , Soviet forces approached and occupied the city of Wilno . Polish forces in the area were relatively weak and the Polish commanders , unsure whether to actively oppose the Soviets , did not utilise the full defensive capabilities of the town and nearby fortified area , although the outcome of the battle would not have been likely any different , given the overwhelming Soviet numerical superiority . Prelude . Wilno , capital of the Wilno Voivodship ( province or region ) , was an important industrial centre in the north - eastern part of Poland and the sixth largest city in that country at the time . Administratively a part of the Grodno - based III Military Corps Area and under Józef Olszyna - Wilczyński , it was also an important garrison and mobilization centre . In the pre - war period , the city housed the entire Polish 1st Legions ' Infantry Division , as well as the headquarters and the 4th Uhlan Regiment of the Wileńska Cavalry Brigade . Air cover was provided by the majority of the 5th Air Regiment stationed at the nearby airfield of Porubanek ( modern Kirtimai ) . In addition , the city of Wilno was a mobilization centre for the 35th Reserve Infantry Division . Before the outbreak of war , the 1st Division had been secretly mobilized and sent towards Różan in northern Mazovia . The Wileńska Cavalry Brigade soon followed and in the first days of September 1939 left the city for Piotrków Trybunalski . The air assets were attached to the Modlin Army and the Narew Group fighting against the German units trying to break through from East Prussia . By 7 September the 35th Division was fully mobilized and transported to Lvov ( modern Lviv , Ukraine ) ; the city was left defenceless . The military commander of the city , Colonel Jarosław Okulicz - Kozaryn , decided that in case of attack by German or Soviet forces , he had insufficient forces for a successful defence and thus his task could only be to allow civilians to evacuate to neutral Lithuania ( this was also realised , albeit not very clearly , by General Józef Olszyna - Wilczyński , commander of the 3rd military district which Wilno was also in ) . On 17 September , the city had 14 , 000 soldiers and militia volunteers , but only 6 , 500 of them were armed . Before the battle , the numbers of armed soldiers rose slightly as some disorganized units trickled in , but the number of unarmed volunteers decreased , as Okulicz - Kozaryn ordered unarmed volunteers not to participate in any hostilities . Before the Soviets arrived , the Polish forces formed about 10 infantry battalions , supported by approximately 15 light artillery and anti - tank guns and about five anti - aircraft guns . The defenders also had some 40 machine guns . On 18 September , the commander of the Belarusian Front , Comandarm ( roughly a general ) , Mikhail Kovalyov , ordered the capture of Wilno by groups of the 3rd and 11th Armies . The 3rd Army delegated the 24th Cavalry Division and the 22nd and 25th Armoured Divisions under Combrig ( senior to colonel but junior to divisional commander ) , Pyotr Akhlyustin , to advance from the northeast and the 11th Army delegated the 36th Cavalry Division and the 6th Armoured Division under Combrig Semyon Zybin to advance from the southeast . Their task was to secure the city by the evening of 18 September ; but due to logistical difficulties and the overestimation of the Polish defences , the operation was revised with the aim of securing the city by the morning of 19 September . The battle . On 18 September , at around 17 : 00 , Okulicz - Kozaryn received reports of Soviet forces approaching from Oszmiana ( today , Ashmyany ) . They consisted of armoured scouts which had engaged Polish infantry units on their approach . Okulicz - Kozaryn then ordered all units to fall back toward the Lithuanian border , Korpus Ochrony Pogranicza units , as the most experienced , were to screen the withdrawal . Podpułkownik ( Lieutenant Colonel ) Podwysocki was dispatched to inform the Soviets that Polish forces did not intend to defend Wilno , but he was shot at and returned to the Polish lines . As Okulicz - Kozaryn had already left the city , Podwysocki decided to defend it , even though most of the forces previously in the city had left with Okulicz - Kozaryn . The first Soviet attack on the evening of the 18 September was repulsed by the Polish defenders . Subsequently the Soviets continued to push into Wilno . By the end of the day the Soviets had secured the airfield and made several thrusts into the city , taking the Rasos Cemetery . By the morning of 19 September the advanced Soviet armoured units had been reinforced with infantry and cavalry . The Polish defenders delayed the Soviet advance , particularly by holding the bridges , but later that day the poorly coordinated Polish defence collapsed and the Soviets took control of the city . Aftermath . Polish units had either surrendered , or withdrawn , disorganized , towards the Lithuanian border or deeper into Poland . The Soviets gave Wilno ( later called Vilnius ) to Lithuania . Lithuanian troops entered the city on 27 – 28 October . The defence of Wilno has been criticized by some Polish historians , who point out that if properly organized , the Polish forces would have been able to hold onto Wilno and delay the Soviets by several days , similar to the defence of Grodno ( in which some of the units which withdrew from Wilno took part ) . Nonetheless this could have only been a symbolic defence , as the Polish forces had no real way of stopping the overwhelming Soviet advance .