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
Russian entry into World War I of Austria of Germany and the Austro-Hungarian Empire. The consensus of scholars includes scant mention of Russia, and briefly mentions Russia's defense of Orthodox Serbia, its pan-Slavic roles, its treaty obligations with France, and its concern for protecting it status as a great power. The Archduke Franz Ferdinand of Austro-Hungary was assassinated by Bosnian Serbs on 28 June 1914 to protest Austrian takeover of a largely Slavic province. Vienna was unable to find evidence that Serbia had sponsored the assassination but a month later issued an ultimatum to Serbia, which it knew would be rejected and thus lead to war.