Causes of World War I corrective." British Diplomat Arthur Nicolson wrote in May 1914, “Since I have been at the Foreign Office I have not seen such calm waters.” On 28 June 1914, Archduke Franz Ferdinand of Austria, heir presumptive to the Austro-Hungarian throne, and his wife, Sophie, Duchess of Hohenberg, were shot dead, by two gun shots in Sarajevo by Gavrilo Princip, one of a group of six assassins (five Serbs and one Bosniak) coordinated by Danilo Ilić, a Bosnian Serb and a member of the Black Hand secret society. The assassination is significant because it was perceived by Austria-Hungary as an existential challenge
Muhamed Mehmedbašić the way to Sarajevo, gendarmes searched the train; fearing they were on to him, he threw the knife out the window. Potiorek was planned to be assassinated at the end of March 1914, when the new mufti Čaušević was to be enthroned in Sarajevo. However, upon hearing that Archduke Franz Ferdinand of Austria would come to Sarajevo on Vidovdan, the Black Hand changed their minds. The Archduke's scheduled visit on Vidovdan (28 June), a Serbian national holiday, was perceived as an insult. Ilić summoned Mehmedbašić and informed him on 26 March that the plan now was to murder Archduke Franz