The 1920 Kiev Offensive (or Kiev Expedition, Kiev Operation), often considered to be the campaign that started the Polish–Soviet War, was an attempt by the armed forces of the newly re-emerged Poland led by Józef Piłsudski, in alliance with the Ukrainian exiled leader Symon Petliura, to seize the territories of modern-day Ukraine which fell under the Soviet control after the Bolshevik Revolution. The operation led to a Soviet counteroffensive resulting in the creation of the short-lived Galician Soviet Socialist Republic. The Polish-Soviet War ended with the Peace of Riga of 1921.