The Russian Revolution had an immediate effect in Minsk. A Workers' Soviet was established in Minsk in October 1917, drawing much of its support from disaffected soldiers and workers. After the Treaty of Brest-Litovsk, German forces occupied Minsk on 21 February 1918. On 25 March 1918, Minsk was proclaimed the capital of the Belarusian People's Republic. The republic was short-lived; in December 1918, Minsk was taken over by the Red Army. In January 1919 Minsk was proclaimed the capital of the Belorussian SSR, though later in 1919 (see Operation Minsk) and again in 1920, the city was controlled by the Second Polish Republic during the course of the Polish-Bolshevik War between 8 August 1919 and 11 July 1920 and again between 14 October 1920 and 19 March 1921. Under the terms of the Peace of Riga, Minsk was handed back to the Russian SFSR and became the capital of the Belorussian SSR, one of the founding republics of the Union of Soviet Socialist Republics.