The Polish–Lithuanian War was an undeclared war fought in the aftermath of World War I between newly independent Lithuania and Poland, with fighting mainly in the Vilnius and Suwałki regions, which was part of the Lithuanian Wars of Independence and lasted from May 1919 to 29 November 1920. From the spring of 1920 onward, the conflict happened alongside the wider Polish–Soviet War and was affected by its progress. It was subject to unsuccessful international mediation at the Conference of Ambassadors and the League of Nations.
After World War I, the military and political situation in the region was chaotic, as multiple countries, notably Lithuania, Poland, and Soviet Russia, vied with each other over control of overlapping areas. The Polish–Lithuanian conflict was centered on Vilnius, which the Council of Lithuania declared the capital of the restored Lithuanian state. Control of Vilnius was transferred from Germans to Poles on January 2, 1919, but the Polish paramilitary lost the city to the Bolsheviks on January 5. The Polish Army seized Vilnius again on April 19, 1919 and came in contact with the Lithuanian Army fighting in the Lithuanian–Soviet War. Despite the antagonism over Vilnius, the Lithuanian and Polish armies sometimes cooperated when fighting against a common enemy, the Bolsheviks. As Lithuanian–Polish relations worsened, the Entente drew two demarcation lines in hopes to stall further hostilities. The lines did not please either side and were ignored. The first clashes between Polish and Lithuanian soldiers occurred on April 26 and May 8, 1919, near Vievis. With the Polish coup against the Lithuanian government failing in August 1919, the front stabilized until the summer of 1920.
In July 1920, Polish forces retreated due to reverses in the Polish–Soviet War and the Lithuanians followed the retreating troops to secure their lands as delineated in the Soviet–Lithuanian Peace Treaty. However, the Red Army was the first to enter Vilnius. In August 1920, Poland won the Battle of Warsaw and forced the Soviets to retreat. The Polish Army encountered Lithuanian opposition, defending their new borders, which the Polish government considered illegitimate. Thus, the Polish invaded Lithuanian-controlled territory during the Battle of Sejny. Pressured by the League of Nations, Poland signed the Suwałki Agreement on October 7, 1920. The agreement left the Suwałki region on the Polish side and drew a new incomplete demarcation line, which left Vilnius vulnerable to a flanking maneuver.
On October 8, 1920, Polish general Lucjan Żeligowski staged a mutiny, secretly planned and authorized by the Polish chief of state Józef Piłsudski. Żeligowski's forces marched on Vilnius and captured it one day before the Suwałki Agreement was to formally come into effect. Żeligowski proclaimed the creation of the Republic of Central Lithuania with its capital in Vilnius. Their further offensive towards Kaunas, the temporary capital of Lithuania, was halted by the Lithuanians, who thus defended their independence. On November 29, 1920, a ceasefire was signed. Overall, from early 1919 to late 1920, Vilnius would switch rule as many as seven times between Lithuanians, Poles and the Bolsheviks. The Republic of Central Lithuania was incorporated into Poland as the Wilno Voivodeship in 1922. The prolonged mediation by the League of Nations did not change the situation and the status quo was accepted in 1923. In March 1923, the Conference of Ambassadors recognized the armistice line as a de jure Polish–Lithuanian border, awarding Vilnius to Poland. However, the International Court of Justice in The Hague arbitrated in 1931 that Poland broke international law by occupying Vilnius. Lithuania remained adamant regarding its claim to Vilnius as its constitutional capital throughout the whole interwar, and breaking all diplomatic relations with Poland due to the latter's control of the city. Diplomatic relations were only restored as a result of the March 1938 Polish ultimatum to Lithuania. Vilnius was regained by Lithuania on 28 October 1939, following the Soviet–Lithuanian Mutual Assistance Treaty, twenty years after losing its capital. However, Lithuania as a whole lost its independence less than a year later following the Soviet ultimatum and occupation of the Baltic states.
The Polish–Lithuanian War was an undeclared war fought in the aftermath of World War I between newly independent Lithuania and Poland, with fighting mainly in the Vilnius and Suwałki regions, which was part of the Lithuanian Wars of Independence and lasted from May 1919 to 29 November 1920. From the spring of 1920 onward, the conflict happened alongside the wider Polish–Soviet War and was affected by its progress. It was subject to unsuccessful international mediation at the Conference of Ambassadors and the League of Nations.
After World War I, the military and political situation in the region was chaotic, as multiple countries, notably Lithuania, Poland, and Soviet Russia, vied with each other over control of overlapping areas. The Polish–Lithuanian conflict was centered on Vilnius, which the Council of Lithuania declared the capital of the restored Lithuanian state. Control of Vilnius was transferred from Germans to Poles on January 2, 1919, but the Polish paramilitary lost the city to the Bolsheviks on January 5. The Polish Army seized Vilnius again on April 19, 1919 and came in contact with the Lithuanian Army fighting in the Lithuanian–Soviet War. Despite the antagonism over Vilnius, the Lithuanian and Polish armies sometimes cooperated when fighting against a common enemy, the Bolsheviks. As Lithuanian–Polish relations worsened, the Entente drew two demarcation lines in hopes to stall further hostilities. The lines did not please either side and were ignored. The first clashes between Polish and Lithuanian soldiers occurred on April 26 and May 8, 1919, near Vievis. With the Polish coup against the Lithuanian government failing in August 1919, the front stabilized until the summer of 1920.
In July 1920, Polish forces retreated due to reverses in the Polish–Soviet War and the Lithuanians followed the retreating troops to secure their lands as delineated in the Soviet–Lithuanian Peace Treaty. However, the Red Army was the first to enter Vilnius. In August 1920, Poland won the Battle of Warsaw and forced the Soviets to retreat. The Polish Army encountered Lithuanian opposition, defending their new borders, which the Polish government considered illegitimate. Thus, the Polish invaded Lithuanian-controlled territory during the Battle of Sejny. Pressured by the League of Nations, Poland signed the Suwałki Agreement on October 7, 1920. The agreement left the Suwałki region on the Polish side and drew a new incomplete demarcation line, which left Vilnius vulnerable to a flanking maneuver.
On October 8, 1920, Polish general Lucjan Żeligowski staged a mutiny, secretly planned and authorized by the Polish chief of state Józef Piłsudski. Żeligowski's forces marched on Vilnius and captured it one day before the Suwałki Agreement was to formally come into effect. Żeligowski proclaimed the creation of the Republic of Central Lithuania with its capital in Vilnius. Their further offensive towards Kaunas, the temporary capital of Lithuania, was halted by the Lithuanians, who thus defended their independence. On November 29, 1920, a ceasefire was signed. Overall, from early 1919 to late 1920, Vilnius would switch rule as many as seven times between Lithuanians, Poles and the Bolsheviks. The Republic of Central Lithuania was incorporated into Poland as the Wilno Voivodeship in 1922. The prolonged mediation by the League of Nations did not change the situation and the status quo was accepted in 1923. In March 1923, the Conference of Ambassadors recognized the armistice line as a de jure Polish–Lithuanian border, awarding Vilnius to Poland. However, the International Court of Justice in The Hague arbitrated in 1931 that Poland broke international law by occupying Vilnius. Lithuania remained adamant regarding its claim to Vilnius as its constitutional capital throughout the whole interwar, and breaking all diplomatic relations with Poland due to the latter's control of the city. Diplomatic relations were only restored as a result of the March 1938 Polish ultimatum to Lithuania. Vilnius was regained by Lithuania on 28 October 1939, following the Soviet–Lithuanian Mutual Assistance Treaty, twenty years after losing its capital. However, Lithuania as a whole lost its independence less than a year later following the Soviet ultimatum and occupation of the Baltic states.
Background
Demographic situation
According to the 1897 Russian census, the disputed city of Vilnius had a linguistic breakdown of 30% Polish-speaking, 40% Jews, and 2% Lithuanian-speaking; however, the percentage of Lithuanian speakers in the surrounding countryside was a few times higher than that of Polish speakers – the population was 35% Lithuanian- and 12% Polish-speaking in Vilnius county (if excluding its centre – Vilnius city), and in Trakai county it was 59% Lithuanian- and 11% Polish-speaking. According to the 1916 German census, Poles were the most numerous among all local nationalities and constituted 53% or 53.67% of the city's population, 50% in the entire Vilnius census region and the vast majority in the Vilnius census district.
At the end of 1918, four groups claiming authority existed in Vilnius: the occupational Ober Ost German government, which was preparing to leave the city; the Lithuanian government under Augustinas Voldemaras that had just begun creating the Lithuanian Army; the Polish Committee and the Polish Temporary National Council for Lithuania supported by armed units of the Self-Defence of Lithuania and Belarus; and Vilnius Soviet of Workers Deputies waiting for the Red Army. The Germans refused to provide weapons to Polish paramilitary units which intended to fight the approaching Red Army. The Ober Ost command also denied the Polish request to grant the Polish Land Forces free passage to Vilnius. The Polish Self-Defence was formally absorbed into the Polish Army at the end of December. On 2 January 1919, Poles took over Vilnius from the retreating German troops and the fighting with the city's Bolshevik Worker's Soviet (capturing around 1,000 weapons). Nonetheless, the last German soldiers left the city only on January 4. The Lithuanian government failed to organize a defense of Vilnius. Both the Polish and Lithuanian political leadership realized their inability to resist the invading Bolshevik forces. Hence, on January 2, the Council of Lithuania evacuated from Vilnius to Kaunas. After some fighting, the local Polish forces lost Vilnius to the Bolsheviks on January 5. Lithuanians relied on the aid of German troops to stop the Red Army offensive before it reached Kaunas.
At first, the Soviets were successful but this came to a halt in February 1919 due to failures at the battles of Jieznas, Kėdainiai, and Alytus. On February 5, Poland signed an agreement with Germany regulating the withdrawal of the German army from western Belarus and giving the Polish army the opportunity to march eastward. On February 14, 1919, Polish troops came into contact with the Bolshevik army near Vawkavysk. On April 16, 1919, the Polish Army launched a wide-ranging offensive against the Bolsheviks from Lida to Vilnius. On April 19, 1919, the Polish cavalry under Władysław Belina-Prażmowski captured Vilnius. On April 22, 1919, Józef Piłsudski issued the Proclamation to the inhabitants of the former Grand Duchy of Lithuania, in which he announced that the region's fate would be decided democratically. He also established the Civil Administration of the Eastern Lands, headed by Jerzy Osmołowski. An important strategic success for the Polish side was the capture of Grodno on April 28, 1919, from which the Germans withdrew.
After that, Polish troops advanced further west and northwest. The situation was utilized by the Lithuanian army, which entered Ukmergė on May 3, and started an offensive further south and southwest. Polish–Lithuanian relations at the time were not immediately hostile, both armies met in several points (Merkinė, Vievis and Širvintos), and even cooperated against the Bolsheviks in Giedraičiai area on May 11, 1919.
At first, both Poles and Lithuanians cooperated against the Soviets, but soon the cooperation gave way to increasing hostility. Lithuania claimed neutrality in the Polish–Soviet War. As the Polish Army forced its way further into Lithuania, the first clashes between Polish and Lithuanian soldiers occurred on April 26 and May 8, 1919, near Vievis. Though there was no formal state of war and few casualties, by July newspapers reported increasing clashes between Poles and Lithuanians, primarily around the towns of Merkinė and Širvintos. Direct negotiations in Kaunas between May 28 and June 11, 1919, collapsed as neither side agreed to compromise. Lithuania tried to avoid direct military conflict and submitted its case for mediation to the Conference of Ambassadors.
In the Suwałki region, Lithuanian troops, supported by German troops, were advancing in a southerly direction. The entire region was under the control of the German army, which allowed in the southern part to organize Polish administrations and to hold elections to the Polish Sejm in the counties of Augustów, Suwałki and Sejny. However, at the same time, they allowed the formation of Lithuanian administrations in the northern part. Lithuanians controlled Sejny from mid-1918, and entered Suwałki on May 8, 1919.
Diplomatic developments
While World War I was still ongoing, under German tutelage, the two sides established diplomatic ties, signing an agreement in Berlin on 30 June 1918. Lithuania was represented by Augustinas Voldemaras and Konstantinas Olšauskas, while Poland was represented by Adam Ronikier. Both sides recognized each other's statehood. In the treaty, Lithuania guaranteed the rights of the Polish minority, while Poland promised to refrain from anti-Lithuanian propaganda. Voldemaras later maintained that Ronikier renounced Polish claims to Vilnius. However, Alfred E. Senn wrote that the issue of the border and the belonging of Vilnius was not addressed in the treaty, while according to Pranas Čepėnas and Wiktor Sukiennicki the signed agreement mentioned nothing regarding territorial questions. The treaty (published in full by Raimundas Lopata) was of interim nature and stated only that: "With regard to the frontier, a principle of a common frontier is accepted, which will be determined by a joint agreement based on ethnic, historic and economic principles". After the Germans had withdrawn, the Lithuanian side pressed for Poland's recognition of an independent Lithuania with its capital in Vilnius, which the Polish leadership consistently rejected.
Polish leader Józef Piłsudski hoped to revive the old Polish–Lithuanian Commonwealth (see the Intermarium federation) and campaigned for some kind of Polish–Lithuanian union in the Paris Peace Conference. Oppositional Endecja desired Lithuania's annexation to Poland, with granting Lithuanians territorial autonomy within ethnic boundaries. Poland also did not intend to make any territorial concessions and justified its actions not only as part of a military campaign against the Soviets but also as the right of self-determination of local Poles. Due to Polish–Lithuanian tensions, the Allied Powers withheld diplomatic recognition of Lithuania until 1922.
The Lithuanians claimed Vilnius as their historical capital and refused any federation with Poland, desiring an independent Lithuanian state. They regarded Polish federalism as a recreation of Polish cultural and political dominance. The Lithuanian government in Kaunas, designated as the temporary capital, deemed the Polish presence in Vilnius as an illegal occupation. In addition to the Vilnius Region, the Suwałki Region was also disputed. It had a mixed Polish and Lithuanian population.
At the time the international situations of newly independent Poland and Lithuania were unequal. Poland, much larger in territory and population, was dedicated point #13 in Woodrow Wilson's Fourteen Points. It was recognized by all nations of the Entente, officially invited to the Paris Peace Conference, and became one of the founding members of the League of Nations. Poland also enjoyed a close alliance with France.
Lithuania did not receive international recognition (it was first recognized de jure in July 1920 by Soviet Russia as part of the peace treaty) as the Entente hoped to revive the Russian Empire within its former territory, which included Lithuania. Lithuania was looking for support in Germany and Russia. In Paris, Voldemaras made contact with Russian delegates to the Paris Conference, who resented an independent Poland and were also interested in limiting its influence in the east and blocking a Polish-Lithuanian agreement. However, they had no real power in Russia, besides that they themselves considered Lithuania part of Russia, so no agreement was reached. Contacts with the Germans were much more fruitful. Germany realized that France was interested in a strong Polish ally east of Germany; so Germany, for its part, supported the building of Lithuania, which would be unfriendly to Poland. Threatened from both sides, the Lithuanian government turned to Germany for military and financial assistance. German troops remained in Kaunas in early 1919, and the government was supported by German loans. The military presence in Lithuania also gave Germany cover for East Prussia and the ability to control the situation in Russia.
The Lithuanian delegation was also present at the Paris Peace Conference, where its leader Augustinas Voldemaras focused on receiving recognition of independent Lithuania and its borders. Voldemaras demanded 125,000 square kilometers for Lithuania, not only with Vilnius but also Suwałki and Białystok. He also accused Poland of being partitionist, and portrayed Poland as an anti-Semitic state that was a threat to Lithuanian Jews. On the other hand, Voldemaras battled negative propaganda that the Council of Lithuania was a German puppet, that Lithuanians harboured pro-Bolshevik attitudes, or that Lithuania was too small and weak to survive without a union with Poland. Under article 87 of the Versailles Treaty, the Principal Allied Powers reserved to themselves the right to determine Poland's eastern frontier.
The war situation and the unstable political situation in both countries did not facilitate contacts between the two governments. Lithuanians protested the presence of Polish troops on Lithuanian territory in early January 1919, but the information reached Warsaw when Vilnius was already in Bolshevik hands. The Poles responded on February 12 by rejecting Lithuanian demands for lands they considered their own, but offered to open direct diplomatic talks. The Lithuanian delegation reached Warsaw on April 18, a day before the entrance of Polish troops to Vilnius.
Meanwhile, Michal Römer, a Lithuanian patriot and veteran of Polish Legions under Piłsudski, went to Kaunas on a mission, and was expected to convince Lithuanian politicians of federation. However, he only found understanding among Lithuanians of Polish culture. On April 17, Lithuanian politicians categorically rejected the federation's proposals.