Battle of Lwów ( 1939 ) The Battle of Lwów ( sometimes called the " Siege of Lwów " ) was a battle for the control over the Polish city of Lwów ( now Lviv , Ukraine ) between the Polish Army and the invading Wehrmacht and the Red Army . The city was seen as the key to the so - called Romanian Bridgehead and was defended at all cost . First clashes . Initially , the town of Lwów was not to be defended as it was considered too deep behind the Polish lines and too important to Polish culture to be used in warfare . However , the fast pace of the German assault and the almost complete disintegration of the Polish reserve Prusy Army after the Battle of Łódź resulted in the city being in danger of a German assault . On September 7 , 1939 , general Władysław Langner started to organise the defence of the city . Initially the Polish forces were to defend the Bełżec — Rawa Ruska — Magierów line against the advancing German forces . General Rudolf Prich was given command of the Polish forces in the area and on September 11 he prepared a plan of defence of the area . The Polish units were to defend the line of the San river , with nests of resistance along the Żółkiew - Rawa Ruska - Janów — Gródek Jagielloński line . The following day the first German motorised units under Colonel Ferdinand Schörner arrived to the area . After capturing Sambor ( some 66 kilometres from Lwów ) , the German commander ordered his units to break through the weak Polish defences and capture the city of Lwów as soon as possible . The German assault group was composed of two motorised infantry companies and a battery of 150 mm guns . The group outflanked the Poles and reached the outskirts of the city , but was bloodily repelled by the - numerically inferior - Polish defenders . The Polish commander of the sector had only three infantry platoons and two 75 mm guns , but his forces were soon reinforced and held their positions until dawn . The same day the command of the city ' s defence was passed to General Franciszek Sikorski , a World War I and Polish - Bolshevik War veteran , and brother of General Władysław Sikorski . The following day the main forces of Colonel Schörner arrived and at 14 . 00 the Germans broke through to the city centre , but were driven back after heavy city fighting with the small infantry units formed of local volunteers and refugees . To strengthen the Polish defences , on September 13 General Kazimierz Sosnkowski left Lwów for Przemyśl and assumed command over a group of Polish units trying to break through the German lines and reach the city of Lwów . The German commander decided to fall back and encircle the city waiting for more reinforcements to arrive . His forces achieved a limited success and captured the important suburb of Zboiska together with surrounding hills . However , the Polish forces were also reinforced with units withdrawn from central Poland and new volunteer units formed within the city . In addition , the Polish 10th Motorised Brigade under Colonel Stanisław Maczek arrived and started heavy fighting over the suburb of Zboiska . The town was re - captured by the Polish forces , but the surrounding hills remained in German hands . The hills gave a good overview of the city centre and the German commander placed his artillery there to shell the city . In addition , the city was almost constantly bombed by the Luftwaffe . Among the main targets for the German air force and artillery were churches , hospitals , water plant and power plants . New enemy . On September 17 , 1939 , the Soviet Union declared all pacts with Poland null and void as the Polish state had in their opinion ceased to exist , and joined Nazi Germany in the occupation of until then Polish territories . The forces of the 6th Red Army of the Ukrainian Front under Filipp Golikov crossed the border just east of Lwów and started a fast march towards the city . The Soviet invasion made all plans of the defence of the Romanian Bridgehead obsolete and the Polish commander of the defence of Lwów decided to withdraw all his units to the close perimeter and decided to defend only the city itself instead of screening the whole area . This strengthened the Polish defences . On September 18 the German air force dropped thousands of leaflets over the city urging the Poles to surrender . This was ignored and a general assault was started on the city , but yet again it was repelled . The intervention of the Red Army on 17 September made necessary some changes in the German plan of operations . In the early morning of September 19 the first Soviet armoured units arrived to the eastern outskirts of the city and the suburb of Łyczaków . After a short fight the Soviet units were pushed back . However , overnight the Soviet forces completed the encirclement of the city and joined up with the German army besieging Lwów from the west . The Polish defences were composed mainly of field fortifications and barricades constructed by the local residents under supervision of military engineers . General Sikorski ordered organised defence of the outer city rim , with in - depth defences prepared . In the morning of September 19 the first Soviet envoys arrived and started negotiations with the Polish officers . Colonel Ivanov , the commander of a tank brigade , announced to the Polish envoy Colonel Bronisław Rakowski that the Red Army entered Poland to help it fight the Germans and that the top priority for his units was to enter the city of Lwów . The same day the German commander sent his envoy and demanded that the city be surrendered to Germany . When the Polish envoy replied that he had no intention of signing such a document , he was informed that the general assault was ordered on September 21 and that the city would most surely be taken . The Hitler ' s evacuation order from September 20 instructed Rundstedt to leave the reduction of Lwow to the Russians . The attack planned by XVIII Corps for 21 September was cancelled , and the corps prepared to move to the west of Vistula - San River line . The following day General Sikorski decided that the situation of his forces was hopeless . The reserves , human resources and materiel were plentiful , but further defence of the city would be fruitless and would only result in more civilian casualties . It was decided to start the surrender talks with the Red Army . Surrender . On September 22 , 1939 , the act of surrender was signed in the suburb of Winniki . The Red Army accepted all conditions proposed by general Władysław Langner . The privates and NCOs were to leave the city , register themselves at the Soviet authorities and be allowed to go home . The officers were to be allowed to keep their belongings and leave Poland for whichever country accepted them . The same day the Soviet forces entered the city and a period of Soviet occupation started . The act of surrender signed in the morning was broken by the Soviets shortly after noon , when the NKVD started arresting Polish officers . They were escorted to Tarnopol , from where they were sent to various Gulags in Russia , mostly to the infamous camp in Starobielsk . Most of them , including general Stanisław Sikorski himself , were murdered in what became known as the Katyn Massacre in 1940 . Order of battle . The Polish defences were still not organised enough and consisted only of token forces . General Sikorski had approximately 11 infantry battalions , 5 batteries of artillery ( mainly 75 mm guns ) , cavalry unit , engineering platoon and a small number of soldiers who retreated into the city . On 18 September two armoured trains : No . 53 and No . 55 ( with two 100 mm howitzers and four 75 mm guns in total ) broke through to the city from Kovel , and took part in further actions . The German units consisted of an entire 1st Mountain Division .