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
Archduke Franz Ferdinand of Austria of Franz Joseph and Maximilian) and of his second wife, Princess Maria Annunciata of Bourbon-Two Sicilies. In 1875, when he was only eleven years old, his cousin Francis V, Duke of Modena died, naming Franz Ferdinand his heir on condition that he add the name "Este" to his own. Franz Ferdinand thus became one of the wealthiest men in Austria. In 1889, Franz Ferdinand's life changed dramatically. His cousin Crown Prince Rudolf committed suicide at his hunting lodge in Mayerling. This left Franz Ferdinand's father, Karl Ludwig, as first in line to the throne. Karl Ludwig died of typhoid fever