Following the October Revolution in 1917 and the subsequent civil war, the Union of Soviet Socialist Republics (USSR) was founded in 1922. After World War II, the Cold War between the Eastern Bloc lead by the USSR and the Western Bloc lead by the USA began and lasted for over 40 years. In 1991, the Soviet Union dissolved. On the flag of the USSR, hammer and sickle represent workers and peasants, while the five-pointed star stands for the unity of the workers of the five continents.