Soviet Union (U.S.S.R.)
Between 1917-1922, a series of socialist revolutions in Russia ousted Tsar Nicholas II and installed a communist government under the leadership of Vladimir Lenin. The Union of Soviet Socialist Republics, also known as the Soviet Union or the U.S.S.R., was a one-party federation comprising Russia, Ukraine, Belarus, Uzbekistan, and Kazakhstan. In 1924 Lenin was succeeded by Joseph Stalin, who led the U.S.S.R. during World War II. Calling for communist revolution worldwide, the Soviet Union was a natural enemy of the far-right Nazi state. Hitler desired Soviet land for expansion of German Nazism and, after a brief pact, invaded in 1941. The U.S.S.R. was dissolved in 1991.