Polish–Lithuanian War

The Polish–Lithuanian War was an armed conflict from 1919 to 1920 over disputed borders after World War I, especially control of the Vilnius region.

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Vilnius Region: A historically contested area of Lithuania centered on Vilnius, claimed by both Lithuania and Poland after World War I. Its sovereignty and control were the war’s central territorial dispute.
Sejny Uprising: A 1919 Polish uprising in the Sejny area against Lithuanian administration, amid competing claims over the borderland. It was an early armed confrontation in the broader Polish–Lithuanian struggle.
Józef Piłsudski: A Polish statesman and military leader who served as head of state and commander during Poland’s early independence. His federalist vision and policies shaped Poland’s approach to Lithuania and the eastern territories.
Republic of Central Lithuania: The polity established after Polish forces seized Vilnius in 1920, incorporated into Poland in 1922. Its incorporation formalized the loss of Vilnius from Lithuania’s perspective.
Polish–Soviet War: A war between Poland and Soviet Russia from 1919 to 1921 over borders and political control in Eastern Europe. Its campaigns shaped the military setting and timing of the Polish–Lithuanian conflict.
Suwałki Agreement: A 1920 agreement that set a provisional demarcation line between Polish and Lithuanian forces without settling Vilnius’s status. The agreement exposed the gap between a temporary military line and an agreed political border.
Antanas Smetona: A Lithuanian politician who became the country’s first president in 1919. He led Lithuania during the war and defended its claim to Vilnius.
Vilnius Voivodeship: An administrative province of interwar Poland that included Vilnius and surrounding territories. It institutionalized Polish administration in the region claimed by Lithuania.
Lithuanian Wars of Independence: Armed struggles from 1918 to 1920 through which Lithuania defended its independence against neighboring powers. The Polish conflict formed one front in Lithuania’s broader fight to secure statehood.
Żeligowski's Mutiny: A staged mutiny in October 1920 in which Polish general Lucjan Żeligowski seized Vilnius and established a separate administration. It decisively altered control of the disputed region after the Suwałki Agreement.