Napoleon made another Polish state, “the Duchy of Warsaw”, but after the Napoleonic wars, Poland was split again by the countries at the Congress of Vienna. The eastern part was ruled by the Russian tsar. During World War I all the Allies agreed to save Poland. Soon after the surrender of Germany in November 1918, Poland became the Second Polish Republic ("II Rzeczpospolita Polska"). It got its freedom after several military conflicts; the largest was in 1919-1921 Polish-Soviet War.