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
SMS Viribus Unitis above the casemates. Three more 7 cm K10 guns were mounted on the upper turrets for anti-aircraft duties. Four submerged torpedo tubes were fitted, one each in the bow, stern and on each broadside; twelve torpedoes were carried. Archduke Franz Ferdinand of Austria travelled aboard "Viribus Unitis" in late June 1914 en route to Bosnia to observe military manoeuvres. On 25 June, he boarded the ship in Trieste Harbour and travelled to the mouth of the Neretva River, where he transferred to another vessel. On 30 June, two days after Ferdinand and his wife were killed by Gavrilo Princip in