The Soviet-Polish War (Polish-Bolshevik War in Polish historiography) (1919-1921) is a conflict between the Polish Republic and the Russian SFSR involving the Ukrainian People’s Republic (UPR). The main goal of the Polish leadership, headed by Józef Pilsudski consisted in the restoration of Poland within the historical borders of the Polish-Lithuanian Commonwealth of 1772. The Soviet side initially aimed at establishing control over the western governorates of the former Russian Empire and their “Sovietization”. As the war progressed, the “Sovietization” of Poland also became a goal.

In November 1918, German troops were beginning to leave the territories of Lithuania and Belarus, so, these areas were occupied by the Red Army’s Western Army. The Lithuanian Soviet Republic (December 16, 1918) and the Socialist Soviet Republic of Belarus (January 1, 1919) were established in the liberated areas. In February 1919, Soviet troops faced the Polish army units. Thus, the Polish-Soviet front was formed. In early March, Polish troops crossed the Neman and launched an offensive on the territory of the newly-formed on February 27 Socialist Soviet Republic of Lithuania and Byelorussia (Litbel). The Poles, fighting, advanced to the East and occupied the entire territory of the republic during the spring and summer of 1919. By the end of August, they had reached the border of the Russian SFSR, where the front stabilized. In October the parties concluded an armistice and began peace negotiations, interrupted at the end of 1919 on the initiative of Poland. In the early January 1920, Polish troops captured Dvinsk (Daugavpils), which was later given to the Republic of Latvia. In March, Polish forces launched an offensive to the south and took Mozyr.