Austria-Hungary:
- Alliance with Germany: Austria-Hungary had a strong alliance with Germany, which was known as the Dual Alliance. This alliance obligated both countries to support each other in case of war.
- Annexation of Bosnia and Herzegovina: In 1908, Austria-Hungary annexed the provinces of Bosnia and Herzegovina, which were previously part of the Ottoman Empire. This action created tensions with Serbia, which had hoped to expand its territory into these provinces.
- Ultimatum to Serbia: After the assassination of Archduke Franz Ferdinand of Austria by a Serbian nationalist in 1914, Austria-Hungary issued an ultimatum to Serbia that was seen as extremely harsh and unreasonable. Serbia accepted most of the demands but rejected some, prompting Austria-Hungary to declare war on Serbia.
- Start of World War I: Austria-Hungary's declaration of war on Serbia triggered a chain of events that led to the outbreak of World War I.
Italy:
- Triple Alliance: Italy was initially part of the Triple Alliance with Germany and Austria-Hungary. However, Italy had its interests and rivalries, particularly with Austria-Hungary over territories in the Balkans and the Adriatic Sea.
- Neutrality: When World War I broke out, Italy initially remained neutral, citing that the alliance was defensive and Austria-Hungary had started the war.
- Entry into the war: In 1915, Italy joined the Allied Powers (which included Britain, France, Russia, and later the United States) after reaching a secret agreement with them. By joining the Allies, Italy sought territorial gains, including parts of Austria-Hungary's Tyrol and Küstenland regions, as well as control over the Adriatic Sea.
In summary, Austria-Hungary played a direct and central role in starting World War I by issuing the ultimatum to Serbia and declaring war on that country following the assassination of Archduke Franz Ferdinand. On the other hand, Italy initially remained neutral and chose to enter the war later on based on its interests and diplomatic agreements, but did not hold the same level of responsibility for starting the conflict.