Italian participation: world war one
Italy had been allied to the German and Austro-Hungarian Empires since 1882, but had its own designs against Austrian territory in the Trentino, Istria and Dalmatia, and maintained a secret 1902 understanding with France, effectively nullifying its alliance commitments. Italy refused to join Germany and Austria-Hungary at the beginning of the war, because their alliance was defensive, while Austria had declared war on Serbia. The Austrian government started negotiations to obtain Italian neutrality in exchange for French territories (Tunisia), but Italy joined the Entente by signing the London Pact in April and declaring war on Austria-Hungary in May 1915; it declared war against Germany fifteen months later.
In general, the Italians enjoyed numerical superiority, but were poorly equipped. The Italians went on the offense to achieve their territorial goals. In the Trentino front, the Austro-Hungarian defence took advantage of the elevation of their bases in the mostly mountainous terrain, which was anything but suitable for military offensives. After an initial Austro-Hungaric strategic retreat to better positions, the front remained mostly unchanged, while Austrian Kaiserschützen and Standschützen and Italian Alpini fought bitter close combat battles during summer and tried to survive during winter in the high mountains. The Austro-Hungarians counter-attacked in the Altopiano of Asiago towards Verona and Padua in the spring of 1916 (Strafexpedition), but they also made little progress.
Beginning in 1915, the Italians mounted 11 major offensives on the other front, the Isonzo front (the part of the border north of Trieste), all repelled by the Austro-Hungarians, who had the higher ground. In the summer of 1916, the Italians captured the town of Gorizia. After this minor victory, the front remained practically stable for over one year, despite several Italian offensives, again all on the Isonzo front. In the fall of 1917, thanks to the improving situation on the Eastern front, the Austrians received large reinforcements, including German assault troops. On October 26, they launched a crushing offensive that resulted in the victory of Caporetto: the Italian army was routed, but after retreating more than 100km, it was able to reorganise and hold at the Battle of the Piave River. In 1918, the Austrians repeatedly failed to break the Italian line, and, decisively defeated in the Battle of Vittorio Veneto, surrendered to the Entente powers in November.
Throughout the war, Austro-Hungarian Chief of Staff, Conrad von Hötzendorf had a deep hatred for the Italians because he had always perceived them to be the greatest threat to his state. Their betrayal in 1915 enraged him even further. His hatred for Italy blinded him in many ways, and he made many foolish tactical and strategic errors during the campaigns in Italy.