German reunification
During the Cold War, West Germany was a democratic country (Politicians were elected in free elections), was allied with the United States of America and had a capitalist economic system (Businesses were owned by citizens).  East Germany was a communist country, a one-party state.  The communist party ruled all the time, elections were only for show, and all businesses were owned by the state.  Like other states in the Soviet bloc, it was controlled by the Soviet Union.