After the October Revolution in 1917 he became people's commissar for nationalities in the first Soviet government. In 1922 he became general secretary of the Party Central Committee, a powerful post which enabled him to gradually isolate and destroy his political rivals after Lenins death. In the 1930's Stalin became virtual dictator of the USSR.

In 1928 he launched the first 5-year plan for the forceful and rapid industrialization of the economy. He also initiated a disastrous collectivization of the peasantry that led to wide-spread famine in the Ukraine. Between 1934 and 1938 he inaugurated a massive purge of the party, armed forces, and intelligentsia in which millions of so-called 'enemies of the people' were imprisoned, exiled, or shot. This period is also known as the 'Great Terror'

After the German invasion Stalin, as war leader, assumed the title of generalissimo. The victory over Nazi Germany resulted in oppressive Soviet control over the liberated countries in Eastern Europe.

After 1945 he resumed his repressive measures at home, and after his death he was denounced by Khrushchev for crimes against the Party, and under Gorbachev many of Stalin's victims were rehabilitated.