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
Assassination of Archduke Franz Ferdinand Popović shortly after Easter (Orthodox Easter as given by Dedijer: 19 April 1914), for the assassination, as evidenced by the testimony of Ilić, Čubrilović, and Popović at the Sarajevo trial. Three youths – Gavrilo Princip, Trifko Grabež, and Nedeljko Čabrinović – Bosnian Serb subjects of Austria-Hungary, living in Belgrade, testified at the Sarajevo trial that at about the same time (a little after Easter), they were eager to carry out an assassination and approached a fellow Bosnian Serb and former guerrilla fighter known to be well connected and with access to arms, Milan Ciganović, and through him Major Tankosić and