In the troubled postwar period Mussolini organized his followers, mostly war veterans, in the Fasci di combattimento, which advocated aggressive nationalism, violently opposed the Communists and Socialists, and dressed in black shirts like the followers of D'Annunzio. Amid strikes, social unrest, and parliamentary breakdown, Mussolini preached forcible restoration of order and practiced terrorism with armed groups. In 1921 he was elected to parliament and the National Fascist party (see fascism) was officially organized. Backed by nationalists and propertied interests, in Oct., 1922, Mussolini sent the Fascists to march on Rome. King Victor Emmanuel III permitted them to enter the city and called on Mussolini, who had remained in Milan, to form a cabinet.
As the new premier, he gradually transformed the government into a dictatorship. In 1924 the Socialist deputy Matteotti was murdered. Opposition was put down by an efficient secret police and the Fascist party militia, and the press was regimented. Parliamentary government ended in 1928, and the state economy was reorganized along the lines of the Fascist corporative state. Conflict between church and state was ended by the Lateran Treaty (1929).
Mussolini was called Duce [leader] by his followers; his official title was "head of the government," and he held, besides the premiership, as many portfolios as he saw fit. His ambition to restore ancient greatness found expression in grandiloquent slogans and speeches and in the erection of monumental buildings. The encouragement he gave to the already high Italian birth rate, his imperialistic designs, and his incitement of extreme nationalist groups created an explosive situation.