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–Serbia relations of Serbian revolts during the 1848 Revolutions were not opposed by the Habsburg rulers. Serbian claims were not recognized by Hungary was eventually placated with the Austro-Hungarian Compromise of 1867, further angering Serbian nationalists. One notable flare-up between the two countries was the 1906-1909 economic conflict known as the Pig War which occurred simultaneously with the diplomatic and military crisis over the Austrian annexation of Bosnia. Ultimately, the tensions between the two countries could not withstand the strain of Assassination of Archduke Franz Ferdinand of Austria by Bosnian Serbs in 1914. Following the July Crisis, Austria invaded Serbia to punish