Why did Italy join the Allies in 1915?

On 23 May 1915, Italy declared war on its former ally, Austria-Hungary. The Triple Alliance was reduced to an alliance between Germany and Austria-Hungary and Europe no longer seemed quite as finely balanced into two opposing camps as it had at the outbreak of war. But why did Italy abandon the Central Powers? 

Italy had always been the shakiest member of the European alliance system. By 1914, the Triple Entente of Russia, France and the United Kingdom had developed into a working alliance. They faced the Triple Alliance of Germany, Austria-Hungary and Italy. Germany and Austria-Hungary’s military alliance was solid. Its strength was forged from a messy combination of compromise, necessity, exigency and shared geographic and political goals.

Cartoon showing the disparity between the Triple Alliance members - Italy strains to reach the heights of Germany and Austria-Hungary

These factors did not apply as clearly to Italy. In fact, there were real tensions between Italy and Austria-Hungary – a shared border, competing irredentist claims over Alpine and Adriatic territory and the prospect of territorial gains in the Balkans as a crumbling Ottoman Empire rolled back to its Anatolian heartlands.

The result was that Germany and Austria-Hungary were never quite able to glue Italy into their alliance system as firmly as the other great powers fitted into theirs. Italy’s ambiguous position was brought into sharp focus at the outbreak of war – whilst other European powers were sucked into the vortex of conflict, Italy remained neutral. On 2 August 1914, the Italians issued a Declaration of Neutrality.

Only nominally considered to be a great power by the other members of that European club, Italy suddenly found herself courted by both sides. The stakes were high – for the Central Powers, Italian naval power, if combined with the navies of the Ottoman Empire and Austria-Hungary, could significantly shift the Mediterranean balance of power. France would be forced to devote precious land and sea resources to defend its shared border and the British would face the prospect of their vital Suez Canal lifeline being cut off.

King Victor Emanuel III of Italy

On the Entente side, adding Italy would not only free up the Mediterranean resources to be deployed against the main German threat but also open up an entirely new 600 kilometre long front with Austria-Hungary. The Allies, understanding the strength of Germany, had consistently tried to pierce the perceived soft underbelly of Austria-Hungary.

In the end, the Allies could promise Italy what Austria-Hungary could not bring herself to permit. Under the terms of the Treaty of London, signed in April 1915, Italy was promised a cornucopia of territorial gains. In the north, a belt of territory stretching from Trentino through the South Tyrol to Trieste would become Italian.

Perhaps more enticingly they were promised Balkan gains that revived dreams of an Italian Empire. The additions, evoking the glories of Rome and the Venetians, would see Italian control of parts of Dalmatia, numerous islands along Austria-Hungary’s Adriatic coast, the Albanian port city of Vlore (known in Italian as Valona).

Italian alpine troops fighting in the First World War Agence Rol [Public domain or Public domain], via Wikimedia Commons

In addition, they were promised a protectorate over a vast swathe of Albania and the prospect of further territory from the Ottoman Empire. Finally, concrete financial assistance was provided in the form of a loan of £50 million from the Allies.

Italy thus entered into the First World War with the mouthwatering prospect of feasting on the territorial remains of two decaying empires. It would be sorely disappointed with the outcome. By the end of the war, 615,000 Italians had been killed in action or died of wounds. Its prize for all that spilt blood and spent treasure was far less than had been promised; control of South Tyrol and Trieste.

Signing of the Treaty of Versailles in the Hall of Mirrors By Helen Johns Kirtland (1890-1979) and Lucian Swift Kirtland (died 1965) (US National Archives) [Public domain], via Wikimedia Commons

Italy entered the peace negotiations with high hopes but ended up leaving Versailles with very little. Disappointment, resentment and anger would sow the bitter seeds for future fascist foreign policy and an Italian desire to right the wrongs of the First World War in any future conflict.