54°30′N 25°45′E / 54.500°N 25.750°EThe Republic of Central Lithuania (Polish: Republika Litwy Środkowej, Lithuanian: Vidurio Lietuvos Respublika), commonly known as the Central Lithuania, and the Middle Lithuania (Polish: Litwa Środkowa, Lithuanian: Vidurinė Lietuva, Belarusian: Сярэдняя Літва, romanized: Siaredniaja Litva), was an unrecognized short-lived puppet state of Poland, that existed from 1920 to 1922. It was founded on 12 October 1920, after the successful Żeligowski Mutiny, during which the volunteer 1st Lithuanian–Belarusian Division under the command of general Lucjan Żeligowski seized the Vilnius Region that Lithuania made claims to. It was incorporated into Poland on 18 April 1922.
Vilnius, the historical capital of Lithuania, had a majority Polish-speaking population with a Lithuanian-speaking minority of only 2–3%. Therefore, the Polish authorities decided that the region should belong to the newly-established Polish state, and attempted to implement this idea using military force, ignoring the Curzon Line and taking advantage of the fact that victorious Poles after the Battle of Warsaw were advancing to the East against the Bolsheviks in the Polish–Soviet War. The Poles reasoned that they were justified in seizing as many mixed areas as possible, as well as to protect the Catholic, predominantly Polish-speaking population in disputed areas. Being utterly militarily outmatched, Lithuania did not stand a chance to maintain control of the region. This led to the renewal of Polish–Lithuanian War, where the so-called Żeligowski Mutiny, secretly ordered by Józef Piłsudski, was part of the military operation, fully supported and backed on the flanks by the Polish army, and consequently to the establishment of the so-called Republic of Central Lithuania.