 By 1919, the White armies were in retreat and by the start of 1920 they were defeated on all three fronts. However, the Polish-Soviet War broke out that year, after Poland tried to annex parts of Belarus and Western Ukraine; by May 1920 it had captured Kiev. After forcing the Polish Army back, Lenin urged the Red Army to push into Poland itself, believing that the Polish proletariat would rise up to support the Russian troops and thus spark European revolution. Although Trotsky and other Bolsheviks were sceptical, they eventually agreed to the invasion. However, the Polish proletariat did not rise up, and the Red Army was defeated at the Battle of Warsaw. The Polish armies began to push the Red Army back into Russia, forcing Sovnarkom to sue for peace; the war culminated in the Peace of Riga, in which Russia ceded territory to Poland and paid it reparations.
