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
Serbs of Croatia of the World War I, all organizations that the government considered favored unification of South Slavs or Serbia, which was on the side of the Allied Powers, were banned. Josip Frank's associates took advantage of some provocations and the anger of the people after the assassination of Archduke Franz Ferdinand by Serb Gavrilo Princip and organized anti-Serbian demonstrations. After a stone was thrown on a parade in which the image of Franz Ferdinand was carried true Zagreb, many cafés and gathering places of pro-Yugoslav politicians as well as Serb-owned shops were demolished. Croat-Serb Coalition MP's were also attacked. On the