In the Soviet Union, Stalin, unlike Hitler in Germany, had no need to form a political party and to seek election in order to gain a position of sufficient power to install single party rule. As explained in Chapter 5, following the Bolshevik Revolution the Constituent Assembly was dissolved in January 1918. Left, though not right opposition parties remained and though mostly suppressed by the summer of 1918, throughout the civil war some, mainly Left SRs, remained in the Congress of Soviets. At the end of the civil war, at the Tenth Party Congress, in March 1921, Lenin erected a single party state. All political parties other than the Communist Party were banned and independent trade unions were made illegal. Strong party discipline was made compulsory; opposition within the Communist Party, permitted by the statute of 1919, was banned (Carr 1966, Vol. 2: 208). In October 1921, nearly 25 per cent of party members were expelled from the Communist Party (Carr 1966, Vol. 1: 211-13). From mid-1921, the party organization (Politburo and Central Committee) began to displace the importance of Sovnarkom which had been the centre of the emergency government during the civil war (Rigby 1979: 191-213).