Fortress of Arad their honor. The most famous prisoner in the fortress of Arad was undoubtedly Gavrilo Princip, who on 28 June 1914 killed the heir to the throne of Austria-Hungary, Archduke Franz Ferdinand and his wife, Sophie, in Sarajevo, which led to the outbreak of World War I. About the inhuman conditions in which prisoners were held in the fortress of Arad warned Ştefan Cicio Pop, deputy of the Romanian National Party in an interpellation to the Hungarian parliament in Budapest during 1917. After the first World War, the fortress was occupied by allied Serbian and French troops under French command, until
History of Russia (1892–1917) was Serbia's territorial rival in the region, and Germany remained the Ottoman Empire's protector. Russia tied itself more closely to Serbia than it had previously. The complex system of alliances and Great Power support was extremely unstable; among the Balkan parties harboring resentments over past defeats, the Serbs maintained particular animosity toward the Austro-Hungarian annexation of Bosnia and Herzegovina. In June 1914, a Serbian terrorist assassinated Archduke Franz Ferdinand, heir to the throne of Austria–Hungary, which then held the Serbian government responsible. Austria–Hungary delivered an ultimatum to Serbia. Serbia submitted to the first 2 of 3 cases of the ultimatum;