When WW1 broke out, Italy was part of an alliance with Germany and Austria, the Triple Alliance as it was called. It was, by design, a defensive alliance: that is one which required the nations to assist each other in case of aggression. There was no immediate obligation in case one of the members of the alliance was the aggressor.

Now, the history of the alliance makes things a bit more complex. Italy had joined it in 1882 - Austria and Germany were already allied with each other. It was a difficult choice as Italy had fought three Independence Wars against the Austrians to achieve its unification; but at the time the relations with France were extremely tense and there was a major concern that Italy could find itself isolated. Therefore the agreement with the Austrians had been taken as a necessary sacrifice to keep on the German's good side.

And originally, this was still a defensive agreement, covering Italy's back in case the French wanted to persist in a hostile policy - which in fact they did; as the tension between Italy and France remained high through the 1880s, reaching a peak during the tenure of the revanchist George Boulanger as Ministry of War.

Right at the time when Boulanger begun his rapid decline, Francesco Crispi became the new Italian Prime Minister, opening a phase known as "Crispi age", from 1887 to 1896. Immediately Crispi, who was strongly anti-French renewed the treaty favoring a more energic alignment with Germany and Austria, hopeful that the Triple Alliance could be used as an offensive leverage against the French.

With the fall of the Boulangist in France, and the realization that the ongoing tariff war was more damaging to Italy than it was to France - and more so that neither Germany nor Austria had any intention to antagonize France at the time - Italy begun to return to a more defensive interpretation of the treaty. When Crispi was forced to resign in 1891, his successor insisted on a revision of the Triple Alliance that expanded some bi-lateral agreements of 1887 into the tri-lateral text. Among these, there was one specific article.

Article seven of the Triple Alliance (as per 1891 - but renewed in 1896, 1901 and 1912) introduced a principle of mutual compensation in the Balkanic region. According to which, Austria and Italy would refrain from expand there or - if forced to do so - would only proceed after coming to a mutual agreement and offering suitable compensation for any expansion.

This clause had already been stretched in 1908 when Austria had annexed Bosnia-Herzegovina. Italy though, had gained in exchange (more or less) the Austrian acceptance of its penetration in Albania and of the annexations following the Italo-Turkish war of 1911-12. So that the Triple had been renewed in 1912.

And yet, during the early years of the XX Century, the relations between Italy and France had improved significantly; so that the Triple Alliance had become more of an established fact for the Italian diplomacy, than a useful instrument: something that it was necessary to renew since not doing so would have meant worsening the Italian relations with Germany.

When the war broke out, Austria was clearly the aggressor; and the Italians could remain neutral, as they were expected to. Of course they had informed both the Germans and Austrians of their neutrality.

Now, more interesting, the Italians - as soon as the Austrian intentions of permanent occupation of Serbia became clear - had called the attention of their allies (and especially that of the Germans) on article 7. Since for Austria to initiate a war in the Balkans, as well as to make territorial gains, without even opening talks of compensation to the Italians, was a clear violation of the treaty.

What the Italian diplomacy wanted to make clear was the fact that, if the Austrians did not provide compensation in a timely manner, Italy would have considered the Triple Alliance broken; and thus relieved of any obligation, not only of assistance but of neutrality too.

As a matter of fact, the Germans understood perfectly and urged the Austrians to offer the requested compensation. Unfortunately, the Austro-Hungarian Empire was a terribly complex machine made of Kingdoms within Kingdoms within Kingdom. If they had given Trent and Istria to the Italians they would have weakened the Austrian core of the Empire; more so, in doing that, they would have stirred the aspirations of all the independentist forces within their territory. The Rumenians would have demanded to join Romania in exchange for their support of the Central Empires. The Croats would have demanded the restoration of their national Crown, and similarly the Czechs, and so on...

And thus, the talks of compensation to the Italians stalled.

Now, in Italy there were other things going on. The long tenured Prime Minister Giovanni Giolitti (of the liberal center-left) had left his position in March 1914 over a matter of internal politics. He hda been replaced, as usual with Giolitti, by a man of his designation - the leader of the liberal national-right Antonio Salandra. Salandra was an expression of a sort of minority government, while the majority of the Chamber was still made of Giolitti's fraction. But Giolitti was too weak to take the lead back for the time being; reason for the Salandra parenthesis. Giolitti, with his majority, was favorable to keep Italy neutral and negotiate with Austria for those compensations. Salandra, was favorable to the intervention on the side of the Entente. Meanwhile, both the Italian Foreign Ministry, Antonio di San Giuliano and the Chief of Staff Alberto Pollio (a supporter of the Triple) had died, on October 1914 and July 1914 respectively. They were replaced by Sidney Sonnino (a man of the liberal right, who continued the policy initiated by San Giuliano, but was in fact slightly more favorable to the Entente) and Luigi Cadorna (Pollio's old antagonist, who made preparations for the intervention on the German side, but was personally less favorable to the Triple).

With this set up, and the talks with the Austrians and Germans stalling, Italy entered the Spring of 1915 in a climate of growing interventionist exhaltation. While most of the population and the poltical forces were in fact favorable to the neutrality, there was a large and noisy minority that demanded an intervention on the French and British side. Strong with this climate and the support of the press and most active fractions of the public opinion, and confident of the agreement reached with the Treaty of London - while Giolitti tried one extreme attempt by meeting informally with the German former Chancellor von Bulow - Salandra avoided the risk of a confidence vote by cutting out the Parliament and went directly to the King.

Salandra offered his resignation without any Parliament vote, forcing the King's hand to either accept his resignation and then necessarily replacing him with a neutralist Ministry led by Giolitti, or confirm him in his position, making it impossible for the Parliament to deny confidence to him immediately after, without going explicitly against the king. The King choose Salandra, the Parliament approved with large majority the special powers law that anticipated the declaration of war. And on May 24^th 1915 Italy declared war on Austria-Hungary.