|Lithuanian invasion of Poland|
Lithuanian Vickers M1936 tanks and infantry wait for orders to cross the Lithuanian-Polish frontier on September 19, 1939.
|Date||September 19 - September 23, 1939|
|Location||Wilno region, Poland|
|Result|| Decisive Lithuanian victory
The Lithuanian invasion of Poland, codenamed Operation Mindaugas by the Lithuanian Army High Command (Operacija Mindaugas in Lithuanian), was an armed conflict between the Republic of Lithuania supported by Nazi Germany and the Soviet Union, and the Second Polish Republic, lasting from September 19 to September 23, 1939, during the German invasion of Poland in the opening phases of the Second World War.
On August 23, 1939, Nazi Germany and the Soviet Union signed a Non-Aggression Pact (the Ribbentrop-Molotov pact), with secret clauses assigning spheres of influence in the area of the Baltic Sea. The Baltic states of Estonia and Latvia, eastern Poland and Finland was assigned to the Soviet sphere of influence, and Lithuania and the western part of Poland was assigned to the German sphere of influence.
On September 1, when Germany finally invaded Poland, they offered Lithuania the disputed regions of Vilnius and Suvalkai if they joined the war on the side of the Germans. As the Lithuanian government debated whether to accept the offer, a border incident at 3:00 on September 17 claimed the lives of 5 Lithuanian soldiers and 10 Polish soldiers. The next day, Lithuanian President Antanas Smetona presented an ultimatum for the Polish government: Cede all territories taken by Poland in 1920 including Vilnius, or they would declare war on Poland, joining the side of Germany and take it back by force.
On September 19, Lithuanian troops crossed the Lithuanian-Polish frontier, which marked the beginning of the Lithuanian military campaign to recapture Vilnius. On September 21, the Lithuanian forces finally captured Vilnius after somewhat heavy losses, and on September 23, colonel Jarosław Okulicz-Kozaryn capitulated to the Lithuanian Commander-in-Chief Vincas Vitkauskas,
The annexation of the Suvalkai and Vilnius regions was confirmed by the Lithuanian parliament (Seimas) resolution on October 15, 1939.
Background to the conflict Edit
At the conclusion of World War I, new states began carving themselves niches on the European continent. Two such countries were Poland and Lithuania. They had been dismembered in the partitions of the late eighteenth century. Immediately upon reconstitution, both states conflicted over Vilnius and its surrounding territories. The city was the historic capital of Lithuania. However, after the Union of Lublin in 1569, Vilnius became a more cosmopolitan city. Gradually, Poles came to outnumber Lithuanians. Lithuanians continued to predominate in the countryside. By 1918, Poles and Jews made up a majority of the population of Vilnius, with a small Lithuanian minority of only 1%. Such demographic obstacles were the legacy of the Poles under the Polish-Lithuanian Commonwealth, which reduced the population of ethnic Lithuanians within Vilnius. Later the Russian occupation of Lithuania from the early 19th century onward claimed their share of the demographic situation due to Russification and purges.
Lithuania declared her independence on February 16, 1918. The titular monarchy of the Monaco-born King Mindaugas II, the official government from July through November 1918, was quickly replaced by a republican government. This was followed by two years of turbulence. The vanquished Germans retreated and the Bolsheviks entered the Vilnius territory in late 1918. In turn, Polish and Lithuanian volunteers drove the Red Army out of Lithuania — Poland entering Vilnius first on April 19, 1919. During the summer of 1920, the bolsheviks re-occupied the territory. Subsequently, Russia concluded an armistice with Lithuania, turning over to her the capital and surrounding areas. The peace treaty caused renewed fighting to break out between Poland and Lithuania. Finally, after much maneuvering — including the intervention of the League of Nations — the Treaty of Suvalkai was signed on October 7, 1920; the Vilnius territory was to remain in Lithuanian hands. This situation was to change with lightning speed. Just two days after the signing of the treaty, Polish general Lucjan Zeligowski, with Marshal Jozef Pilsudski's blessing, staged a rebellion and led Polish forces into the eastern third of Lithuania, occupying Vilnius. As a result of this the capital was relocated to Kaunas, which was officially designated the provisional capital of Lithuania. The Lithuanian counterattack was halted by the League of Nations; diplomatic efforts failed to bring Vilnius back to Lithuania. The Conference of Ambassadors recognized the existing border in 1923. The inter-war years were to see continuing tensions between the two countries over the Vilnius question. Lithuania would not officially renounce the capital; Poland would not give up the predominantly Polish city. A stalemate ensued for eighteen years, despite secret and sometimes high-level contacts between the belligerents. Nothing appeared able to break the deadlock, which included the lack of diplomatic relations and a technical state of war. An administration line was created between the antagonists. It was here that Polish-Lithuanian hostility was focused.
However, the political situation in Lithuania was also deteriorating. Following a succession of conservative governments, Lithuania's first elected government of the left was overthrown in a military coup d'état on December 17, 1926 (1926-ųjų perversmas) and was largely organized by the military. The coup brought the Lithuanian National Union, the most conservative party at the time, to power. Before 1926, it had been a fairly new and insignificant nationalistic party: in 1926, its membership numbered about 2,000 and it had won only three seats in the parliamentary elections. The Lithuanian Christian Democrats, the largest party in the Seimas at the time, collaborated with the military and provided constitutional legitimacy to the coup, but did not accept any major posts in the new government and withdrew in May 1927. After the military handed power over to the civilian government, it ceased playing a direct role in political life. While Smetona resumed office as president, Augustinas Voldemaras that later was leader of the far-right Iron Wolf movement served as Prime Minister. Voldemaras was removed from his office in September 1929, but Smetona and his party, however, remained in power until 1939.
The Trasninkai incident Edit
The administration line which divided Poland and Lithuania ran 520 km through the eastern third of Lithuania. It began in the north near Dvinsk, and ran through Giedraičiai and Merkinė to the Nemunas River halfway between Seinai and Gardinas, ending in the south at Vištytis. A "no-man's land" approximately one km wide divided Polish and Lithuanian forces. There were no formal markings on the Lithuanian side. However, high poles with straw brooms at the top designated the Polish side of the frontier. Lithuanian border police patrolled one side, while the Poles used a component of their regular armed forces, the Polish Frontier Guard Corps (Korpus Ochrony Rogranicza - KOP), to supervise the line.
Skirmishes were not uncommon along the frontier. Although the area was usually quiet, there were also instances of poachers, border runners, and outlaws darting back and forth across the line, occasionally drawing fire from Polish and Lithuanian guards. There were also non-violent events which nonetheless produced tensions. Border posts were sometimes moved in the night. A superficially humorous example was also reported. Apparently, a Lithuanian farmer constructed a haystack on his land. During the night, however, the stack was quietly moved to the Polish side of the line. While it was a relatively minor incident, accumulated minor events served only to heighten tensions. This caused the exchange of gunfire to become more frequent, especially as 1937 wore on.
The border zone was decidedly an unhealthy place to look over even momentarily. Guards were ever on the alert and ready to take pot shots at suspicious shadows. Poachers and smugglers found it very precarious to carry on their nefarious activity.
Since 1927, at least seven guards had been killed and thirteen wounded in various incidents. Yet, there was a measure of cooperation on the frontier. For example, Lithuanian farmers could be allowed by Polish officials to cross the line and perform farm-work on land that may have ended up in no-man's land or in Polish hands. However, apart from minimal official traffic that had been agreed to by the respective governments, there were few breaches of the line. On the Lithuanian side, responsibility for guarding the border was divided up into regions by the authorities. For example, the Alytus area border police district was divided into six regions. The district was administered by a chief located in Merkinė. Each of the six regions was based in small towns or villages. For our purposes, we will focus in on region two. Here the line zigzagged between the Nemunas and Merkys rivers. The police outpost of this region was located in the village of Trasninkai.
In the early morning hours of Friday March 11, near the village of Trasninkai, Lithuanian border police officer Justas Lukoševičius was on a routine patrol when he heard two, then three shots. He informed his superior officer, Vaitkus, who in turn instructed Lukoševičius to investigate the matter. Upon returning to the scene, he spotted a Polish soldier running in the bushes, apparently in the direction of Polish territory. Lukoševičius called for him to halt. Instead, the Pole fired one round in his direction from the bushes. Lukoševičius returned the fire with four rounds. Six rounds were subsequently fired at Lithuanian police officers who had gathered at the scene. A search uncovered Stanislaw Serafin, a recent recruit to the KOP, who was lying in the bushes mortally wounded. He was brought to Trasninkai where he died later that morning.
Usually, such incidents were handled at the local level in an attempt to forestall escalation. On this occasion, however, Polish radio and newspapers picked up the story and fanned anti-Lithuanian sentiment. Protests were held in Warsaw, Vilnius, and four other cities where the crowds shouted for military action against Lithuania. There is evidence that the Camp of National Unity was involved in organizing the protests.
On March 13, the Polish government issued a threatening statement accusing Lithuania of provocation. On the following day, the Senate of the Republic of Poland called for the establishment of diplomatic relations and for the Lithuanian renunciation of claims to Vilnius. Upon receiving news that Poland was considering extreme measures, President Antanas Smetona was verging towards agreeing to discuss diplomatic relations, but changed his mind at almost the last minute. On the night of March 14, the Lithuanians, acting through France's envoy to Warsaw, proposed a commission to investigate the shooting incident and to agree on measures to avoid such incidents in the future. This was a partial measure that clearly did not satisfy Poland, which responded by refusing, in the first paragraph of the ultimatum delivered three days later, to establish such a commission. At the same time Lithuanian diplomats approached foreign powers in a bid for international support.
Poland then presented an ultimatum to Lithuania to re-establish the relations. A period of 24 hours was set for a response; at the end of which Poland would declare war if Lithuania did not renew diplomatic relations. President Smetona held a government meeting late on the night of March 18 to decide whether or not to accept the ultimatum. Lithuania clearly lacked international support and the demand was rather tame. A refusal would have cast Lithuania in an unfavorable light as an unreasonable disputant that had irrationally rejected peaceful diplomatic relations for eighteen years. Lithuanian diplomats were divided on the issue, while popular opinion was strongly against accepting the ultimatum. Various campaigns for the Lithuanian "liberation" of Vilnius had attracted massive participation. Knowing that it was weaker at the time and that under such circumstances there would be no support from other countries, Lithuania accepted the ultimatum and it was signed by representatives of both states in Tallinn, Estonia. After that, several quiet protests happened in Lithuania. Positive effects of the ultimatum included treaties about railway transport, postal exchange, and other means of communication, finally allowing the population to exchange letters and place phone calls across the borders. Although Lithuania officially continued to claim Vilnius as its capital, with diplomatic relations re-established due to the ultimatum, antagonism between the two states over the region reduced and the Vilnius Liberation Union was also closed. However, this would soon be overshadowed once again by Germany's expansionist foreign policy.
The Lithuanian National Socialist Party, which was ideologically similar to the German Nazi Party, gained a large voice in the city's politics. In the 1938 election, the National Socialists won the majority of seats and negotiated a settlement to hand over Klaipėda to Germany. A majority of the town's Jewish population, foreseeing this change in the cards, had already fled the area.
By late 1938, Lithuania had lost control over the situation in Memel. In the early hours of March 23rd, 1939, after a oral ultimatum had made a Lithuanian delegation travel to Berlin, the Lithuanian Minister of Foreign Affairs Juozas Urbšys and his German counterpart Joachim von Ribbentrop signed the Treaty of the Cession of the Memel Territory to Germany in exchange for a Lithuanian Free Zone for 99 years in the port of Memel, using the facilities erected in previous years. German forces seized the territory even before the official Lithuanian ratification. The United Kingdom and France, as after the revolt of 1923, did not actively protect the autonomy of the territory. It was under these conditions that the Seimas was forced to approve the treaty, hoping that Germany would not press any other territorial demands upon Lithuania. Hitler had anticipated this aboard a naval ship, and at dawn sailed into Memel to celebrate the return “heim ins Reich” of the Memelland. This proved to be the last of a series of bloodless annexations of territories in which German-speaking minorities lived. The reunion with Germany was welcomed by the majority of the population, both by Germans and by Memellanders.
Tensions in EuropeEdit
Following the loss of Klaipėda, General Stasys Raštikis visited Warsaw between May 12th and 13, suggesting a military alliance with Poland. However, the Polish government treated his proposition lightly and lost a small, but potentially important, ally. The Poles focused on relief from the French in case a war should erupt with Germany.
On August 23rd, 1939, Nazi Germany and the Soviet Union signed a Non-Aggression Pact (the Ribbentrop-Molotov pact), with secret clauses assigning spheres of influence in the area of the Baltic Sea. The Baltic states of Estonia and Latvia, eastern Poland and Finland was assigned to the Soviet sphere of influence, and Lithuania and the western part of Poland was assigned to the German sphere of influence. The news of the Molotov-Ribbentrop Pact came as a shock to the Lithuanians and the rest of the world.
Concerns over the possible existence of secret protocols were first expressed by the intelligence organizations of the Baltic States scant days after the pact was signed, and speculation grew stronger when Soviet negotiators referred to its content during negotiations for military bases in those countries. A war between Germany and Poland now seemed inevitable.
The German offerEdit
On September 1, 1939, at 04:40, Nazi Germany invaded Poland. On September 3, after Hitler refused to abide by the ultimatum presented by the French and British governments, the United Kingdom and France declared war on Germany. However, the same day the Germans invaded Poland, Ribbentrop made an unofficial visit to President Smetona at 1000 hours. During this meeting, Ribbentrop presented an offer to the Lithuanians: Ally with Germany in the attack on Poland, and the Lithuanians would be rewarded with the Vilnius region taken from them by Poland in 1920 and Suvalkai region. To assist the Lithuanian army with the capture of these territories, German military units would be at disposal for the Lithuanian High Command. President Smetona was interested, but asked for time to ask the cabinet and the Seimas (parliament).
At noon a meeting began at the Presidential residence on the outskirts of Kaunas. President Antanas Smetona presided. In attendance were the Cabinet, under the leadership of Prime Minister Jonas Černius; the president of the Seimas, Konstantinas Šakenis; the Army Chief of Staff, Division General Stasys Pundzevičius; and Commander-in-Chief General Raštikis. The meeting was tense.
The debate went on for days, and while Lithuanian diplomats were divided on the issue, while popular opinion was strongly against accepting the German offer, as rumors had reached the Lithuanian population. Various campaigns for the Lithuanian "liberation" of Vilnius had attracted massive participation. Passionate feelings about Vilnius were expressed in a popular slogan "Mes be Vilniaus nenurimsim" (we will not rest without Vilnius), part of a poem by Petras Vaičiūnas.
President Smetona received memoranda from nine nationalistic organizations urging the government to accept the offer. However, they remained divided on the issue. Their first concern was the question if the Soviet Union would follow Germany and invade Poland from the east. If they did, their hopes to regain Vilnius would be lost, and they suspected a possible existence of secret protocols. The second major concern was that the diplomatic relations with Poland was improving, and the antagonism between the two states over the region had been reduced since March 1938. Finally was the concern of international response to the acceptance of the German offer, as a positive answer to the Germans could cast Lithuania in an unfavorable light.
The Klėriškės incidentEdit
In the early morning hours of Sunday September 17, 1939 near the village of Klėriškės, the Lithuanian soldiers under the command of Lieutenant Artūras Januševičius were guarding the border station around 500 m south of the village, due to the rising tension resulting from the ongoing war between Germany and Poland.
At 0300 hours the soldiers heard something approaching the border station, and the rest of the soldiers and the border police was alerted. They heard it was a group of men, presumably soldiers, Lieutenant Lukoševičius called for the approaching men to halt. The following part of the incident is surrounded by mystery. Depending on which source is consulted, the details vary from an accidental kill by a warning shot by the Lithuanians to a massacre of the Poles by the Lithuanians, to the Poles opening fire in the belief it was Germans.
A minute after Lukoševičius had called out for the approaching men to halt, a shot was heard. As a result, a firefight between the Lithuanian soldiers and the unidentified men began, and after half an hour they withdrew back to the Polish side of the border. At the same time, shots were fired between Lithuanian soldiers and unidentified men at Klėriškės. A search by the Lithuanian soldiers uncovered several Polish soldiers, many of them recruits of the KOP, along with 3 officers. The soldiers had actually retreated into Lithuania to escape capture by the Germans.
At 0800 hours on September 17, the news reached the Lithuanian people. President Smetona, the Cabinet and Prime Minister Černius the president of the Seimas Šakenis, Army Chief of Staff General Pundzevičius and Commander-in-Chief General Raštikis was surprised by the news of the incident. On the streets of Kaunas and other large Lithuanian cities large crowds were gathering, protesting the so-called Polish "provocation" and urging the army to march on Vilnius.
The news had reached Germany as well, and Ribbentrop sent later that morning a telegram showing sympathy for the Lithuanian soldiers killed in what he called a "Polish provocation". After pressure from the conservative bloc, and of personal interest as well, President Smetona answered Ribbentrop with another telegram, declaring that Lithuania was on the side of Germany in the matter of the Polish question.
At noon President Smetona presented an ultimatum for the Polish government through the Polish embassy in Kaunas: Return all territories taken by Poland in 1920, or they would take it back by force by allying themselves with Germany. They had 48 hours to comply, after that they would declare war on Poland. While the Polish government knew they were in no power to refuse the ultimatum, circumstances prevented the Polish acceptance to arrive the Lithuanians. At 2000 hours President Antanas Smetona ordered the invasion to begin the following day.
Republic of LithuaniaEdit
On September 19th, the Commander-in-Chief of the Lithuanian Armed Forces, General Stasys Raštikis, had 3 infantry divisions, 1 cavalry brigade and an armoured group at disposal for the recapture of Vilnius. The plan for the recapture of Vilnius was the following:
- To the north, the 2nd Infantry Division and a Cavalry Brigade should advance from Širvintos and then continue towards Vilnius from the north.
- To the south, the 1st Infantry Division, the Šarvuočių rinktinė (tank group) and later elements of the German Group Brandt) should capture Troki (Trakai) and then advance on Vilnius from the south.
- The Lithuanian Air Force (Only the Gloster Gladiator Mk. I fighters were made combat ready) and the Luftwaffe (Junkers Ju-87 "Stukas" and Messerschmitt Bf-109s) should support the advancing forces from the air, attacking Polish defences and military units. By request of the Lithuanian government, the Luftwaffe was told not to bomb Vilnius.
- The 3rd Infantry Division should stand guard at their southern border with Poland, facing the Suvalkai/Suwałki region.
The Lithuanian ArmyEdit
The Lithuanian Army consisted of 1,600 Officers and 21,000 Other Ranks organized into:
- 3 Infantry Divisions each of 3 Infantry Regiments and 1 Field Artillery Regiment
- 1 Cavalry Brigade of 3 Regiments.
- 1 Armoured Unit of a staff, 3 tank companies, 1 armoured car company and a training platoon
Each Infantry Regiment had 3 Battalions each of 3 Rifle and 1 Heavy Machinegun Companies.
Each Cavalry Regiment had 4 Horsed Dragoon, 1 HMG and 1 Technical Squadrons. In addition there was a 19th Squadron which acted as a remount centre for the Cavalry Brigade.
Field Artillery had 4 Regiments each with 3 Groups of 3 Batteries (2 batteries of 75 mm M1897 field guns and 1 battery of 105 mm "Schneider" howitzers) of 4 guns and 2 light machineguns attached to each Infantry Division. Each Regiment had 24 M1897 field guns and 12 "Schneider" howitzers. There were as well 1 Independent Heavy Regiment of 2 Groups each of 3 Batteries of 4 Heavy Howitzers.
The Cavalry Brigade had a horse artillery group, consisting of 3 batteries (for each cavalry regiment) with 4 units of 76.2 mm M1902 divisional guns each. There were a special training artillery group in Panemune (Kaunas' district) consisting of 300 soldiers and the 11th Reserve Artillery Regiment in Panevezys, also consisting of 300 soldiers.
The Lithuanian armoured forces (Šarvuočių rinktinė – Armour Group) were created on January 1, 1924, and consisted of a staff, 3 tank companies, an armoured car company and a training platoon. This unit was located in the town of Radviliškis, and had around 500 personnel (soldiers, NCOs and officers).
HQ Troops included 1 Armoured Vehicle Detachment, 1 Motorized Infantry Detachment, 1 Signal Battalion and 1 Engineer Regiment of 3 Pioneer Battalions.
All units were severely under strength and were intended to be brought up to war strength by calling up reservists from the 55,000 strong LSS (Lietuvos Sauliu Sajunga) or Rifle Association which was controlled by the Ministry of National Defence and whose members were under the direct orders of the Army CIC.
Lithuania had no significant navy, consisting only of the minelayer "Prezidentas Smetona", which was built in Germany during the First World War.
Republic of PolandEdit
Wilno (Vilnius), the capital of the Wilno Voivodship (and the original Lithuanian capital), was an important industrial centre in the north-eastern part of Poland and the sixth largest city in that country at that time. Administratively a part of the Grodno-based III Military Corps Area and just before the outbreak of war, the Grodno Operational Group under Józef Olszyna-Wilczyński, it was one of also an important garrison and a 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 Uhlans Regiment of the Wileńska Cavalry Brigade. The 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 Vilna was a mobilization centre of the 35th Reserve Infantry Division.
Already before the outbreak of the 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 of 1939 left the city for Piotrków Trybunalski. The air assets were attached to Modlin Army and the Narew Group fighting against the German units trying to break through from East Prussia. By September 7th the 35th Division was fully mobilized and transported to Lvov (modern Lviv, Ukraine) and 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 has insufficient forces for successful defence, and thus his task can be only to allow civilians to evacuate to neutral Lithuania (this was also supposed, albeit not very clearly, by general Józef Olszyna-Wilczyński, commander of the 3rd military district Wilno was in).
On September 19th, the city had 14,000 soldiers and militia volunteers, but only 6,500 were armed. Before the battle, the numbers of armed soldiers rose slightly as some disorganized formation trickled in, while the number of unarmed volunteers decreased, as col. Okulicz-Kozaryn ordered unarmed volunteers not to participate in any hostilities. Before the Lithuanians initiated their operation to capture Vilnius, the Polish forces formed about 10 infantry battalions, supported by ~15 light artillery and anti-tank pieces, and ~5 anti-aircraft. The defenders had about 40 machine guns.
Order of Battle Edit
At 7:40 on September 19th, as the Soviets were preparing to attack Wilno, two Lithuanian divisions and a cavalry brigade supported by 30 tankettes crossed the Lithuanian-Polish frontier, seizing numerous border stations and villages. The Polish soldiers were taken by surprise, several of whom were taken prisoner. By 10:00, the Lithuanian High Command reported the loss of 5 soldiers and 31 wounded, mainly due to Polish artillery and sniper activity.
At 11:00, Hitler expressed his support of the Lithuanian government, and Ribbentrop immediately promised to send elements of Gruppe Brandt (the unit responsible to secure the left flank of Army Group North) and the I./Panzer-Regiment 10 to support the Lithuanian advance.
Despite pressure from both Hitler and Smetona, Stalin was nonresponsive, as agreements were already made, and the commander of the Byelorussian Front, Comandarm Mikhail Kovalyov, ordered the capture of Wilno by groups of 3rd and 11th Army. 3rd Group delegated 24th Cavalry Division, and 22nd and 25th Tank Brigades under Combrig Pyotr Akhlyustin to advance from north-east, and 11th Army delegated 36th Cavalry Division and the 6th Tank Brigade under Combrig Semyon Zybin to advance from south east. The task was to secure the city on the same day - by the evening of September 19th, but due to logistical difficulties and overestimation of Polish defences, the operation was revised with the goal of securing the city by the morning of the September 20th.
The advance towards Vilnius went quickly, and by the end of the day the Lithuanians were cutting off the Poles’ supply lines. The Poles had limited resources to halt the Lithuanian and the Soviet advances, though the spearheading units were delayed at several occasions, the most ferocious fighting occurred on September 19-20 at Trakai.
After counterattacking the German and Lithuanian forces, they were forced to retreat, leaving behind a small amount of small arms and artillery pieces. These were incorporated into the Lithuanian Army after the campaign. Russians in the same time faced road obstacles, destroyed bridges and partisan style activity from volunteers from local communities and delaying actions of Korpus Ochrony Pogranicza. Some villages, after supplying from Wilno, were able to halt advance of particular tank groups for many hours, giving in the same time advantage to incoming Lithuanians.
All delaying forces, buying a time to organise the defence of Wilno, were finally pushed back to the city, cutting some of the groups from the main defence line (this unit acted in partisan actions, attacking enemy supply routes etc.)
On September 20, around 13:00, col. Okulicz-Kozaryn received reports of Lithuanian-German forces approaching from the south and north and Soviet tank forces from the east. The Soviet forces consisted of armoured scouts and have engaged Polish infantry units on their approaches. Seeing that a retreat was impossible, Col. Okulicz-Kozaryn than ordered all units to defend the city as well as they could if a capitulation were not possible, and Korpus Ochrony Pogranicza units, as the most experienced, were to face the Soviet advance. Podpułkownik (lt. col.) Podwysocki was dispatched to inform the Lithuanians that Polish forces did not intend to defend Wilno against the Lithuanians, and that they would rather capitulate to Lithuanians than Russians, but was shot at and retreated behind the Polish lines.
Due to a misunderstanding, Russian and Lithuanian forces clashed near the village of Nowosiółki, when the Russians crossed the river and were trying to flank the city from the north and the Lithuanians were trying to cut the Poles off from the river. After a short time of surprise, Russians opened fire on the incoming Lithuanian forces, which made them retreat to Fabjaniszki.
The 1st Division ordered their tankettes and anti-tank artillery to their positions around Fabjaniszki in order to halt the Russian advance and attack south of the bridge, located south to the Śnipiszki outskirts.
Another clash occurred near Krapiwnica, when Lithuanian cavalry units were flanking the city from the south. They encountered Russian tanks and were forced to fall back with heavy casualties. However, later this day German armoured group entered the scene and was able to push the Russians back, gaining the ground till the Rowne Pole.
After this, all advance in hostile areas was discontinued and series of diplomatic exchanges was met, with Stalin finally caving in for Hitler and Antanas’ pressure, giving the rights to Wilno back to Lithuanians, but in the meantime the Russians already prepared the first assault on the city, which failed mainly due the lack if infantry support and the defender’s use of gasoline bombs as the assault was rushed to conquer the city before the Lithuanians could.
The first Lithuanian attack on the evening of the September 20 was repulsed by the Polish defenders. Subsequently Lithuanians supported by German tanks continued to push into the city, and increasingly surrounding the city. By the end of the day the Soviets have secured the airfield, and made several headways into the city, taking the Rasos Cemetery.
By the morning of September 21, the advanced German armour units with German and Lithuanian infantry and cavalry had control of around 80% of city. The Polish defenders delayed the Axis advance, particularly by holding the bridges, but later that day the poorly coordinated Polish defence has collapsed and the Lithuanians took control of the city. 212 Polish soldiers, including Colonel Jarosław Okulicz-Kozaryn and his staff, surrendered to the Lithuanian forces.
On September 23, Colonel Jarosław Okulicz-Kozaryn officially capitulated to the Lithuanian Commander-in-Chief Division General Stasys Raštikis and the commander of the 1st Division, Division General Vincas Vitkauskas, and asked the Lithuanians to stay in Lithuania rather than be transferred to the Russians or the Germans.
On October 6, the government and parliament began moving from the temporarily capital Kaunas to their old capital Vilnius. Hitler, pleased with the Lithuanian military actions of the Polish campaign, kept his word, and accepted a Lithuanian annexation of the Vilnius region, and ceded the so-called "Suwałki triangle" to them as well. The annexation of the Suvalkai and Vilnius regions was confirmed by the Lithuanian parliament (Seimas) resolution on October 15, 1939. The day was marked by military parades through the streets of Vilnius and Kaunas.
The Lithuanian Army was too disorganized for a larger military action; almost emptying their ammunition reserves, they would have suffered a serious reverse against the Russians before the Germans and Russians could agree to let Lithuania secure the Wilno region.
The Lithuanian casualties were officially recorded as 81 dead and 348 wounded - all were named and so this total is probably accurate. On September 28th the Russians announced their own losses as 63 dead and 124 wounded. Including this, 23 tanks were destroyed, as well as 4 BA-10 armoured cars. They also reported they were holding 121 Polish prisoners.
The Polish casualties are controversial, and no clear number of dead can be presented. 126 civilians were killed due to Russian air attacks and collateral damage, mainly during the fighting in Trakai and Wilno. 369 Polish soldiers were taken prisoner during the campaign; 121 of them by the Russians and 248 by the Lithuanian and Germans. The Lithuanians demanded that the Poles should be transferred to them, but only 20% of them were transferred, and the fate of the rest of the soldiers were grimm; either murdered (like the Polish officers in the Katyn massacre) or imprisoned in labour camps (the Gulags).