Why did Lithuania and Poland dispute control of Vilnius after World War I?

The dispute over Vilnius between Poland and Lithuania following World War I was rooted in conflicting visions of national identity and historical territory.12

For Lithuania, Vilnius was the historic capital and a central pillar of its modern national identity. Conversely, many in Poland viewed the city as part of a broader Polish cultural realm, seeking to resurrect the historical political union that had existed until 1795.12

The conflict escalated through a series of military occupations:
* 1919: After Lithuanian forces evacuated the city due to a Soviet advance, Polish troops occupied Vilnius.12
* 1920: Following a brief period of Soviet control, the Red Army ceded the city to Lithuania in a peace treaty. Shortly after, Polish General Lucjan Żeligowski seized the city, establishing the short-lived Republic of Central Lithuania.12
* 1922: The region was formally annexed by Poland, a move Lithuania refused to recognize, leading to 18 years of frozen diplomatic relations.12

The dispute was only temporarily resolved by a 1938 Polish ultimatum forcing the establishment of diplomatic ties, before Vilnius was restored to Lithuania in 1939.12