During the 1920s and the 1930s, Stalin fought and defeated the political influence of Leon Trotsky and of the Trotskyists in Russia, by means of slander, anti-Semitism, programmed censorship, expulsions, exile (internal and external), and imprisonment. The anti–Trotsky campaign culminated in the executions (official and unofficial) of the Moscow Trials (1936–38), which were part of the Great Purge of Old Bolsheviks (who had led the Revolution).[17][33] Once established as ruler of the USSR, General Secretary Stalin re-titled the official Socialism in One Country doctrine as "Marxism-Leninism", to establish ideologic continuity with Leninism, whilst opponents continued calling it "Stalinism".