Mussolini was born in Predappio (Italy) on July 29, 1883, the son of a socialist blacksmith. Largely self-educated, he became a school teacher and socialist journalist in northern Italy. In 1910 he married Rachele Guidi, with whom he had five children. Mussolini was jailed for his opposition to Italy's war in Libya (1911-12). Soon after that, he was named editor of Avanti!, the Socialist Party newspaper in Milan. When World War I began, in 1914, Mussolini first denounced it as "imperialist," but he soon reversed himself and called for Italy's entry on the Allied side. Expelled from the Socialist Party, he started his own newspaper in Milan, Il Popolo d'Italia (The People of Italy), which later became the organ of the Fascist movement.

In turbulent postwar Milan, Mussolini and other young war veterans founded the Fasci di Combattimento in March 1919. This nationalistic, antiliberal, and antisocialist movement attracted lower middle-class support and took its name from the fasces, an ancient symbol of Roman discipline. Growing rapidly after mid-1920, fascism spread into the countryside, where its black-shirt militia won support from landowners and attacked peasant leagues and socialist groups. Opportunistically, fascism shed its initial republicanism, thereby winning sympathy from the army and the king.

When Fascists marched on Rome, King Victor Emmanuel III invited Mussolini to form a coalition government (October 28, 1922). By 1926 the Fascist leader had transformed the country into a single-party, totalitarian regime. In his new "corporative state," employers and workers were organized into party-controlled groups representing different sectors of the economy. The system preserved capitalism and expanded social services, but abolished free trade unions and the right to strike. The Lateran pacts with the Vatican (1929) ended a half-century of friction between church and state and proved to be long-lasting. Another enduring legacy of fascism was a system of industrial holding companies financed by the state.

Adopting an aggressive foreign policy, Mussolini defied the League of Nations and conquered Ethiopia (1935-36). This won him acclaim in almost every sector of the populace. Il Duce's popularity declined, however, after he sent troops to help General Francisco Franco in the Spanish Civil War (1936-39), linked Italy to Nazi Germany, enacted anti-Jewish laws, and invaded Albania (1939).

Mussolini did not enter World War II until June 1940, when the Germans had overrun France. Italy fought the British in Africa, invaded Greece, and joined the Germans in carving up Yugoslavia, attacking the Soviet Union, and declaring war on the United States.

King Victor Emmanuel dismissed Mussolini on July 25, 1943, and in September obtained an armistice with the Allies, who had invaded southern Italy. At the same time, the Germans rescued the sickly Mussolini and made him organize a brutal puppet Social Republic in northern Italy. In the final days of the war Mussolini attempted an escape to Switzerland with his mistress Clara Petacci. Italian partisans captured and shot them on April 28, 1945, at Giulino di Mezzegra near Lake Como.