In the last decades of Tsarist rule, many Siedlce activists (both Polish and Jewish) took part in the 1905 Revolution. After a series of attacks on Russians in all of Poland on Bloody Wednesday (15 August 1906) the Russian authorities organized a pogrom in Siedlce in reprisal on 8–10 September 1906, in which 26 Jews perished. In the wake of the First World War the town was affected by the Polish-Soviet War, being occupied by the Red Army in 1920 and taken over by the Polish Army in 1921.