Polish–Soviet War

The Polish–Soviet War (14 February 1919 – 18 March 1921) was fought primarily between the Second Polish Republic and the Russian Soviet Federative Socialist Republic, following World War I and the Russian Revolution. After the collapse of the Central Powers and the Armistice of 11 November 1918, Vladimir Lenin's Soviet Russia annulled the Treaty of Brest-Litovsk and moved forces westward to reclaim the Ober Ost regions abandoned by the Germans. Lenin viewed the newly independent Poland as a critical route for spreading communist revolutions into Europe. Meanwhile, Polish leaders, including Józef Piłsudski, aimed to restore Poland's pre-1772 borders and secure the country's position in the region. Throughout 1919, Polish forces occupied much of present-day Lithuania and Belarus, emerging victorious in the Polish–Ukrainian War. However, Soviet forces regained strength after their victories in the Russian Civil War, and Symon Petliura, leader of the Ukrainian People's Republic, was forced to ally with Piłsudski in 1920 to resist the advancing Bolsheviks. In April 1920, Piłsudski launched the Kiev offensive with the goal of securing favorable borders for Poland. On 7 May, Polish and allied Ukrainian forces captured Kiev, though Soviet armies in the area were not decisively defeated. The offensive lacked local support, and many Ukrainians joined the Red Army rather than Petliura's forces. In response, the Soviet Red Army launched a successful counteroffensive starting in June 1920. By August, Soviet troops had pushed Polish forces back to Warsaw. However, at the decisive Battle of Warsaw (1920), Polish forces achieved an unexpected victory between 12 and 25 August 1920, turning the tide of the war. This battle, often referred to as the "Miracle on the Vistula", is considered one of the most important military triumphs in Polish history. The war ended with a ceasefire on 18 October 1920, and peace negotiations led to...