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
Bosnia and Herzegovina the annexation proclamation on 6 October 1908. Despite international furor and objections to the Austro-Hungarian annexation, Russians and their client state, Serbia, were compelled to accept the Austrian-Hungarian annexation of Bosnia Herzegovina in March 1909. In 1910, Habsburg Emperor Franz Joseph proclaimed the first constitution in Bosnia, which led to relaxation of earlier laws, elections and formation of the Bosnian parliament, and growth of new political life. On 28 June 1914, a Yugoslav nationalist youth named Gavrilo Princip, a member of the secret Serbian-supported movement, Young Bosnia, assassinated the heir to the Austro-Hungarian throne, Archduke Franz Ferdinand, in Sarajevo—an event