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
Trifko Grabež also hit by bomb shrapnel. Later that day, Gavrilo Princip managed to kill both Archduke Franz Ferdinand and his wife Sophie, Duchess of Hohenberg. Princip and Nedeljko Čabrinović were interrogated by the police. They kept to the promise to not tell anyone. Muhamed Mehmedbašić managed to escape to Serbia but Grabež, Popović and the Čubrilović's were arrested and charged with treason and murder after Danilo Ilić told the police. The police went round and investigated random people in order to identify potential accomplices. Once they spoke to Ilić, he lost his nerve and spilled the beans. All seven of the