London Pact (Italian: Patto di Londra), or more correctly, the Treaty of London, 1915, was a secret pact between the Triple Entente and Italy, signed in London on 26 April 1915 by the United Kingdom, France, Russia, and the Kingdom of Italy. Its intent was to gain the alliance of Italy against its former allies, including Germany.
According to the pact, Italy was to leave the Triple Alliance and join Triple Entente; Italy was to declare war against Germany and Austria-Hungary within a month (this happened against Austria-Hungary within a month, but not until 1916 against Germany). Assuming victory against Germany and its allies, the Triple Entente promised Italy the following territorial gains (see Italia irredenta) at the end of the war:
The Kingdom of Serbia, which was not present nor a signatory, was assigned:
The Kingdom of Montenegro, which was not present nor a signatory, was assigned:
Also, but less precisely, Serbia was assigned:
Italy insisted, and the Allies agreed, that the question of the Adriatic coast between Zara and Istria should be settled after the war. Italy also insisted that Serbia should not be informed about the agreements. However, the Allies overruled this by sending an official note to Serbia on 4 August 1915, confirming the post-war territorial claims of Serbia and Montenegro.
After the war, Italy would only negotiate with Serbia and Montenegro. The Italian delegation staged a walk-out for a number of months when faced with the denial of their territorial demands.
The pact was nullified by the Treaty of Versailles. Before 1918, the contents of the Pact of London had been published to the world by the Bolshevik Russian State. The Fourteen Points, as proposed by U.S. President Woodrow Wilson, contained a number of clauses that argued for ethnic or national self-determination and against respecting the provisions of the Treaty of London:
In Wilson's view, the Pact of London had been arrived by secret contract, hence was not valid. Overall Wilson sought to achieve borders being determined by the populations present in the area rather than by outside parties; the pact of London adjudicated to Italy areas that did not have a majority-Italian population. Wilson believed that Slavic claims to some of the disputed regions were more sound than those of Italy.
Italy ultimately was denied other gains promised in the Treaty: a share of German colonies and control of Albania. Italy tried to establish a physical claim in Anatolia (Turkey), but was quickly forced to evacuate. The partition of the Tyrol on the water divide line was confirmed by the Treaty of St. Germain.
After the war British and French leaders refused to fulfil all the promises in the pact. The irredentist nationalist element of Italy considered this an inexcusable betrayal by these two European allies. The colonial gains by Britain and France from the war further angered the Italians, who felt excluded.
The breakdown of the London Pact helped give rise to a belief in a so-called "mutilated victory" within Italy, which played a role in determining Italian inter-war imperialism. In 1920 Italian nationalists created the Free State of Fiume, although it had not been assigned to Italy in the Treaty of London. This underscored the unstable results of the Treaty of Versailles relative to Italian claims.