Franz Joseph I of Austria of his only son and heir, Crown Prince Rudolf, in 1889, and the assassination of his wife, Empress Elisabeth, in 1898. After the Austro-Prussian War, Austria-Hungary turned its attention to the Balkans, which was a hotspot of international tension because of conflicting interests with the Russian Empire. The Bosnian Crisis was a result of Franz Joseph's annexation of Bosnia and Herzegovina in 1908, which had been occupied by his troops since the Congress of Berlin (1878). On 28 June 1914, the assassination of his nephew, Archduke Franz Ferdinand, in Sarajevo resulted in Austria-Hungary's declaration of war against the Kingdom of
Austria–Germany relations in this unified Germany. Austria-Hungary then turned its imperial ambitions to the Balkan Peninsula; whereas the German Empire focused on building armaments in a race against the United Kingdom (Britain and Ireland). Nevertheless, both the German Empire and Austria-Hungary forged a military alliance with the Kingdom of Italy, forming the Triple Alliance (1882). In the 1910s, Austria-Hungary's ambition of turning Serbia into its protectorate facilitated the Assassination of Archduke Franz Ferdinand (1914), heir to Austria-Hungary's throne. When Austria-Hungary stirred up excuses for a war (First World War) against Serbia, Germany, claiming the Alliance's terms of passive military defence instead of