That agreement, which Italy had required Great Britain and France to accept in April, 1915, before she consented to declare war against the Austro-Hungarian Empire, committed the Entente Powers to the recognition of Italy's right to certain territorial acquisitions at the expense of Austria-Hungary in the event of the defeat of the Central Empires.

By the boundary line agreed upon in the Pact, Italy would obtain certain important islands and ports on the Dalmatian coast in addition to the Austrian Tyrol and the Italian provinces of the Dual Monarchy at the head of the Adriatic.
When this agreement was signed, the dissolution of Austria-Hungary was not in contemplation, or at least, if it was considered, the possibility of its accomplishment seemed very remote.

It was assumed that the Dalmatian territory to be acquired under the treaty to be negotiated in accordance with the terms of the Pact would, with the return of the Italian provinces, give to Italy naval control over the Adriatic Sea and secure the harborless eastern coast of the Italian peninsula against future hostile attack by the Austro-Hungarian Empire.

The boundary laid down in the agreement was essentially strategic and based primarily on considerations of Italian national safety.

As long as the Empire existed as a Great Power the boundary of the Pact of London, so far as it related to the Adriatic littoral and islands, was not unreasonable or the territorial demands excessive.
But the close of active warfare in the autumn of 1918, when the armistice went into effect, found conditions wholly different from those upon which these territorial demands had been predicated.