The original ideology of the state was primarily based on the works of Karl Marx and Friedrich Engels. In its essence, Marx's theory stated that economic and political systems went through an inevitable evolution in form, by which the current capitalist system would be replaced by a Socialist state before achieving international cooperation and peace in a "Workers' Paradise," creating a system directed by, what Marx called, "Pure Communism."
Displeased by the relatively few changes made by the Tsar after the Russian Revolution of 1905, Russia became a hotbed of anarchism, socialism and other radical political systems. The dominant socialist party, the Russian Social Democratic Labour Party (RSDLP), subscribed to Marxist ideology. Starting in 1903 a series of splits in the party between two main leaders was escalating: the Bolsheviks (meaning "majority") led by Vladimir Lenin, and the Mensheviks (meaning minority) led by Julius Martov. Up until 1912, both groups continued to stay united under the name "RSDLP," but significant differences between Lenin and Martov thought split the party for its final time. Not only did these groups fight with each other, but also had common enemies, notably, those trying to bring the Tsar back to power. Following the February Revolution, the Mensheviks gained control of Russia and established a provisional government, but this lasted only a few months until the Bolsheviks took power in the October Revolution, also known as the Great October Socialist Revolution.
Under the control of the party, all politics and attitudes that were not strictly RCP (Russian Communist Party) were suppressed, under the premise that the RCP represented the proletariat and all activities contrary to the party's beliefs were "counterrevolutionary" or "anti-socialist." During the years of 1917 to 1923, the Soviet Union achieved peace with the Central Powers, their enemies in World War I, but also fought the Russian Civil War against the White Army and foreign armies from United States, United Kingdom, and France, among others. This resulted in large territorial changes, albeit temporarily for some of these. Eventually crushing all opponents, the RCP spread Soviet style rule quickly and established itself through all of Russia. Following Lenin's death in 1924, Joseph Stalin, General Secretary of the RCP, became Lenin's successor and continued as leader of the Soviet Union into the 1950s.
The history of the Soviet Union between 1927 and 1953 covers the period of the Second World War and of victory against Germany while the USSR remained under the firm control of Joseph Stalin. Stalin sought to destroy his political rivals while transforming Soviet society with aggressive economic planning, in particular a sweeping collectivization of agriculture and a rapid development of heavy industry. Stalin's power within the party and the state was established and eventually evolved into Stalin's cult of personality. Soviet secret-police and the mass-mobilization Communist party were Stalin's major tools in molding the Soviet society. Stalin's brutal methods in achieving his goals, which included party purges, political repression of the general population, and forced collectivization, led to millions of deaths: in Gulag labor camps, during the man-made famine, and during forced resettlements of population.
World War II, known as "the Great Patriotic War" in the Soviet Union, devastated much of the USSR with about one out of every three World War II deaths representing a citizen of the Soviet Union. After World War II the Soviet Union's armies occupied Central and Eastern Europe, where socialist governments took power. By 1949 the Cold War had started between the Western Bloc and the Eastern (Soviet) Bloc, with the Warsaw Pact pitched against NATO in Europe. After 1945 Stalin did not directly engage in any wars. Stalin continued his absolute rule until his death in 1953.