On May 18, 1944, soldiers of the 2 Polish Corps hung the Polish flag on the ruins of the Monte Cassino monastery.
On 30 January 1930, the Politburo of the Central Committee of the All-Union Communist Party (Bolsheviks) decided to launch the largest resettlement operation in the entire history of the Soviet Union, still referred to today as the 'kulak deportation'.
On 18 March 1921, the treaty ending the Polish-Bolshevik war (the so-called Treaty of Riga) was signed in Riga.