The Fasci Italiani di Combattimento was founded by Mussolini and his supporters in the aftermath of World War I, at a meeting held in Milan in March 1919.

[32] After making his way back to Milan, Mussolini returned to the position of chief editor of Il Popolo d'Italia, the newspaper he had originally founded in November 1914 to advocate for Italian entry into the war.

[35][32] Historian Denis Mack Smith writes that "possibly this inflow of money from big business in no way affected the politics of his paper", but that Mussolini's enemies asked, "why these firms would support such a small newspaper unless it was for services rendered.

"[35] In 1919, after the end of World War I, the Treaty of Versailles resulted in Italy obtaining South Tyrol, Trentino, Istria, and Trieste from Austria-Hungary.

Mussolini used his newspaper in 1919 to espouse an eclectic mix of "dramatic and eye-catching" proposals inspired by views from across the political spectrum, as he was "far more concerned with tactics than with ideas" and discovered that inconsistency did not bother his readers.

[36] Mussolini at this time "appeared successively as champion of the League and then nationalist, as socialist and then conservative, as a monarchist and then republican" and actively wished to keep all his political options open.

[36] The Fasci Italiani di Combattimento was founded by Mussolini and a group of between fifty and two hundred supporters who met in a hall provided by Milanese businessmen in the Piazza San Sepolcro on 23 March 1919.

[37] For the right, Mussolini endorsed nationalist claims over Fiume and Dalmatia, and the Fasci proposed to take the government out of business and transfer large segments of the economy from public to private control.

[38] The manifesto of the Fasci Italiani di Combattimento was published on the following day in Mussolini's newspaper Il Popolo d'Italia, which was closely connected to it.

On 15 April 1919, the offices and printing equipment of the main socialist newspaper, Avanti!, were attacked and destroyed by a group of fascists led by Marinetti and Ferruccio Vecchi.

[42] In a mock funeral procession after the election, members of the Italian Socialist Party carried a coffin that bore Mussolini's name, parading it past his apartment to symbolise the end of his political career.

[45] During the Biennio Rosso, in the summer of 1920, a wave of strikes and factory occupations by socialist workers further persuaded industrialists and landowners to provide financial support to the fascist movement.

[46] They increasingly made use of squads partially composed of military veterans and often led by former army officers to carry out "punitive expeditions" to sack socialist headquarters and break up trade unions.

[48]: 43–44 A few months later, Mussolini decided to transform the relatively decentralised Fasci Italiani di Combattimento into a more tightly organised political party under his control.