Italy Declares War on Austria-Hungary: May 24, 1915

On May 24, 1915, Italy formally declared war on Austria-Hungary, marking its entry into World War I on the side of the Allies. This decision was a significant shift in the dynamics of the war and had profound implications for the conflict’s progression.

Background

• Triple Alliance: Before the outbreak of World War I, Italy was part of the Triple Alliance with Germany and Austria-Hungary. However, Italy had longstanding territorial disputes with Austria-Hungary, particularly over regions such as Trentino and Trieste, which were home to Italian-speaking populations but under Austro-Hungarian control.

• Neutrality: When World War I began in 1914, Italy initially declared neutrality. The Italian government argued that the Triple Alliance was a defensive pact, and since Austria-Hungary had taken the offensive by declaring war on Serbia, Italy was not obliged to join the conflict.

• Secret Negotiations: Throughout 1914 and early 1915, Italy engaged in secret negotiations with both the Central Powers and the Allies. The Allies, particularly Britain and France, were eager to bring Italy into the war on their side to open a new front against Austria-Hungary.

The Treaty of London

• April 26, 1915: Italy signed the Treaty of London with the Allies. In this secret agreement, the Allies promised Italy territorial gains at the expense of Austria-Hungary, including the regions of Trentino, South Tyrol, and Istria, as well as parts of Dalmatia and other territories.

• Strategic Considerations: The Italian government, led by Prime Minister Antonio Salandra and Foreign Minister Sidney Sonnino, believed that joining the Allies would allow Italy to achieve its territorial ambitions and enhance its status as a great power.

Declaration of War

• May 23, 1915: The Italian Parliament approved the decision to enter the war, and King Victor Emmanuel III issued a declaration of war against Austria-Hungary.

• May 24, 1915: Italian forces began military operations along the Austro-Hungarian border, initiating the Italian Front, which would become one of the major theaters of World War I.

Consequences and Significance

• Military Campaigns: The Italian Front saw numerous battles, including the long and grueling series of battles along the Isonzo River. The mountainous terrain posed significant challenges, and the front became known for its harsh conditions and high casualties.

• Impact on the War: Italy’s entry into the war forced Austria-Hungary to divert resources and troops to the new front, relieving some pressure on the Western and Eastern Fronts where the Allies were engaged against Germany.

• Post-War Outcomes: After the war, Italy’s territorial gains were formalized in the Treaty of Saint-Germain and the Treaty of Rapallo. However, the post-war settlements did not fully satisfy Italian expectations, contributing to the “mutilated victory” sentiment that fueled nationalist and fascist movements in the subsequent years.

Italy’s decision to join the Allies in World War I was a pivotal moment that reshaped the course of the war and had lasting effects on European geopolitics.