Trifko Grabež society. For the next two years he spent most of his spare time with other nationalists who favoured a union between Bosnia and Herzegovina and Serbia. When it was announced that Archduke Franz Ferdinand, the heir to the throne of Austro-Hungarian Empire, was going to visit Bosnia and Herzegovina in June 1914, Colonel Dragutin Dimitrijević, the chief of the Intelligence Department in the Serbian Army and head of the Black Hand, sent seven men, Grabež, Nedeljko Čabrinović, Vaso Čubrilović, Cvjetko Popović, Danilo Ilić, Muhamed Mehmedbašić and Gavrilo Princip to Sarajevo to assassinate him. Each man was given either a revolver
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