Franz Joseph I of Austria the Empire on 6 October 1908. However a diplomatic crisis erupted, as both the Serbs and the Italians demanded compensation for the annexation, which the Austro-Hungarian government refused to entertain. The incident was not resolved until the revision of the Treaty of Berlin in April 1909, exacerbating tensions between Austria-Hungary and the Serbs. On 28 June 1914 Franz Joseph's nephew and heir Archduke Franz Ferdinand, and his morganatic wife Sophie, Duchess of Hohenberg, were assassinated by Gavrilo Princip, a Yugoslav nationalist of Serbian ethnicity, during a visit to Sarajevo. When he heard the news of the assassination, Franz Joseph said
Assassination of Archduke Franz Ferdinand wife planned to visit Sarajevo to open the state museum in its new premises there. Duchess Sophie, according to their eldest son, Duke Maximilian, accompanied her husband out of fear for his safety. As Sophie, although of high aristocratic birth, was not from a dynastic family, her union with the Habsburg heir presumptive could only be a morganatic marriage. Emperor Franz Joseph had only consented to their marriage on the condition that their descendants would never ascend the throne. The 14th anniversary of their marriage fell on 28 June. As historian A. J. P. Taylor observes: Franz Ferdinand was an