On May 12, 1970, General Władysław Anders, Commander-in-Chief of the Polish Armed Forces in 1944-1945, died in exile in London.
On May 12, 1935, Marshal Józef Piłsudski died. He was buried at Wawel, in the crypt under the Tower of Silver Bells.
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'.
Father Jan Cieplak was auxiliary bishop of the Mogilev archdiocese, at that time the largest Roman Catholic archdiocese in the world, covering the whole of Russia up to Sakhalin.
On 18 March 1921, the treaty ending the Polish-Bolshevik war (the so-called Treaty of Riga) was signed in Riga.
The Polish-Bolshevik war broke out on 14 February 1919. The site of the first confrontation was the town of Mosty near Szczuczyn in the Grodno region, where Polish Army units halted the Red Army’s march.