Italian Campaign (World War I)
Italy did not fight on the side of its allies Germany and Austria in 1914 when the war started. In 1915 they joined the Triple Entente, to take places where Austria ruled people who spoke Italian. This was irredentism. They wanted the province of Trento (Trentino), the port of Trieste, and the province of Bolzano-Bozen (Alto Adige/Südtirol), Istria, and Dalmatia.
Italy had hoped to begin the war with a surprise attack, which was to act quickly and capture several Austrian-held cities. However, the war in Italy soon turned to trench warfare, similar to the Western Front.