War, a very great war, was from the beginning the essence of Mussolini's program. His final effort, the war of 1940–43, to his mortification destroyed the Fascist regime. But from the very beginning of his trajectory from 1914 to 1943, from Socialist fanatic to deposed Duce of Fascism, he had unhesitatingly invoked “that fearful and enthralling word: war.” Only war, he insisted in October–November 1914, could produce the genuine national integration missed during Italy's territorial unification in 1859–70. Only war could confirm Italy's membership in the charmed circle of dominant nations: “Either war, or let's end this commedia of [claiming to be] a great power.” The war of 1915–18 that Mussolini and a motley coalition of interventisti helped to force upon parliament and nation through oratorical passion and street violence did not disappoint. The Great War “completed the Risorgimento” through the conquest of Trento, Trieste, and the Brenner frontier. It abolished Austria-Hungary, bled France white, and gave Italy far greater latitude to entertain the ambitions of Mediterranean domination long-current among its governing elite. Above all, the Great War by delayed action made Mussolini himself Duce of Fascism and chief of government.

He had preached war in 1914–15 as a revolutionary conflict that would overthrow “this Italy of priests, pro-Austrians, and monarchists.” The 650,000 deaths, bitter defeats, and innumerable privations along the road to a victory bought too dearly, and Liberal Italy's predictable failure to achieve its inflated war aims in 1918–19 so unhinged the Italian establishment that in 1919–20 it lost command of government. War had indeed become a sort of revolution.