In the summer of 1914, when the great war broke out, the Italy, given the defensive nature of the Triple Alliance and the failure by the Austrians to comply with the commitment to a preliminary consultation with the allies in the event of a crisis, declared its neutrality (3 August), reflecting the orientation of the large majority of both Parliament and the country. Giolittian liberals and a large part of the industrial world are opposed to intervention; the socialists, in compliance with the principles of internationalism; the Catholics, who express the pacifist sentiments of the masses, especially peasants, and the Vatican’s fears that the Italy go to war against Catholic Austria. In favor is a composite minority, divided among the liberal conservatives (who through the war also aim to reaffirm the social hierarchies, shaken by the advance of the workers’ movement), the ‘democratic interventionists’ (who see the war against Austria as an opportunity for the liberation of the oppressed peoples), a part of the revolutionary syndicalists (who consider war the pioneer of the revolution) and finally the nationalists. The monarchy is also in favor, according to which neutrality would condemn Italy to a second-rate location.
On April 26, 1915, with the London Pact, preceded by secret negotiations with the Entente powers, Italy agrees to go to war within one month of signing. To Italy Trentino, Cisalpine Tyrol up to Brenner (with German populations), Istria up to Quarnaro excluding Fiume (with Slavic populations), part of Dalmatia, Valona and the protectorate of Albania, the Dodecanese and the coal basin of Antalya. Unspecified colonial fees are also expected. Street demonstrations (the ‘radiant days of May’) orchestrated by the government follow one another in support of the intervention already decided. The obstacle of the parliamentary majority deployed on a neutralist line is overcome thanks also to Giolitti’s refusal to fully lead the opposition to the war,
On May 24 the Italy enters the war against Austria. The army, led by General L. Cadorna, faces the test with gaps in terms of organization and technical preparation. According to aceinland.com, the offensives launched in the Isonzo and Karst area fail to achieve significant results. 1916 is characterized by the Austrian attempt to eliminate the Italy from the conflict with a ‘punitive expedition’ against the former ally. Salandra, considered responsible for the unpreparedness revealed by the offensive, must resign. In his place, at the head of a ‘national ministry’, Fr Boselli is appointed (June 1916-October 1917). On August 28, 1916, Italy also declares war on Germany. With the illusion of a short-lived conflict gone, the country faces the costs of a grueling war of attrition beyond its means. When the Austrians, reinforced by German forces, break through the lines near Caporetto (24 October 1917) the retreat becomes a disorderly route. Boselli falls and is replaced by VE Orlando (October 1917-June 1919), while in place of Cadorna, disliked by the troops for the brutal discipline and indifference to the lives of the soldiers, goes A. Diaz. In the following months the army managed to contain the offensive of the Austrians, stopped on Monte Grappa and on the Piave and rejected again (June 1918) in a last attempt to win the Italian resistance. The Italian victory comes with the general attack launched on October 24: in the battle of Vittorio Veneto, Austria, now in full dissolution, suffers the definitive defeat.