The Polish–Lithuanian War was an undeclared war fought between Poland and Lithuania after World War I.
Part of the broader Lithuanian Wars of Independence and Polish–Soviet War.
Duration: May 1919 - November 29, 1920.
Main locations: Vilnius and Suwałki regions.
Result: Polish victory.
Territorial changes: Vilnius and Suwałki regions under Polish control until 1939.
Key Events
1918-1919: After WWI, control over Vilnius shifted multiple times between Germans, Poles, Bolsheviks, and Lithuanians.
April 1919: Polish Army seized Vilnius and clashed with the Lithuanian Army.
July 1920: Polish retreat due to the Polish–Soviet War, leading to Soviet and Lithuanian forces entering Vilnius.
August 1920: Success at the Battle of Warsaw allowed Polish forces to reclaim territory from the Soviets.
October 1920: Suwałki Agreement signed under pressure from the League of Nations.
October 8, 1920: Żeligowski's Mutiny, staged by Polish General Lucjan Żeligowski, led to the capture of Vilnius and the proclamation of the Republic of Central Lithuania.
November 29, 1920: Ceasefire signed.
Military and Political Context
Post-WWI chaos with overlapping territorial claims from Poland, Lithuania, and Soviet Russia.
Vilnius was claimed as the capital by both Lithuania and Poland.
Failed international efforts to mediate the conflict, including interventions by the League of Nations.
Soviet–Lithuanian Treaty (July 12, 1920) recognized Lithuanian independence but allowed Soviet troop movements in Lithuania during hostilities with Poland.
Higher percentage of Lithuanian speakers in surrounding countryside.
By 1916, Poles were the majority in Vilnius.
Subsequent Developments
Republic of Central Lithuania (proclaimed October 12, 1920) was later incorporated into Poland as the Wilno Voivodeship in 1922.
Ongoing tensions: Lithuania refused to recognize Polish control over Vilnius, leading to severed diplomatic relations until 1938.
1938 Polish Ultimatum to Lithuania resulted in restored diplomatic relations.
Soviet invasion of Poland in 1939 resulted in Vilnius being returned to Lithuania.
Long-term impact: strained Lithuanian–Polish relations and hindrance to Pilsudski's Intermarium federation vision.
International Involvement
League of Nations: Intervened but was unable to resolve the territorial dispute.
Allies and Entente: Various diplomatic pressures applied; withheld recognition of Lithuania until 1922.
Military Developments
Several demarcation lines were proposed by international mediators but largely ignored by both sides.
Polish success in military operations allowed for strategic advantages in the region.
Conclusion
The war resulted in a significant political and territorial shift in the region, affecting Polish-Lithuanian relations and shaping the interwar period.
The conflict exemplified the complexities of post-WWI territorial disputes and the challenges of international diplomacy in resolving such issues.