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
Otto Merz in an official motorcade in which the Archduke Franz Ferdinand toured Sarajevo, and may have witnessed the assassination of the Archduke by Gavrilo Princip. According to the story told later, Merz reacted quickly to the gunshots. One of the first to reach Franz Ferdinand, he lifted the rather stout Archduke from his seat and carried him to a nearby house. However, that day there were "two" attempts on Franz Ferdinand's life; in the first one, Nedeljko Čabrinović threw a bomb with a 10-second fuse at the archduke's car; the driver accelerated when he saw something thrown at them, and the