10. The Polish-Lithuanian War (1920)
The Polish-Lithuanian War, fought from May 1919 to November 29, 1920, was a pivotal conflict that determined the fate of Vilnius and the Polish-Lithuanian border after World War I. The war began with Polish forces advancing into Lithuanian territory, leading to a series of battles over the disputed Vilnius and Suwałki regions. In October 1920, General Lucjan Żeligowski, under orders from Polish Chief of State Józef Piłsudski, staged a mutiny and captured Vilnius, proclaiming the establishment of the Republic of Central Lithuania. This move effectively incorporated Vilnius into Poland, despite Lithuania’s claims to the city. The conflict concluded with the Treaty of Kaunas on November 29, 1920, which established a ceasefire and a demilitarized zone along the border. However, the underlying territorial disputes remained unresolved, and the status of Vilnius continued to be a contentious issue between Poland and Lithuania until the outbreak of World War II.
