Trifko Grabež was a Bosnian Serb member of the organization the Black Hand involved in the assassination of Archduke Franz Ferdinand of Austria.
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 revolver or a bomb and a small vial of cyanide. They were instructed to commit suicide after Archduke Franz Ferdinand had been killed. It was important to Colonel Dimitrijević that the men did not have the opportunity to confess who had organised the assassination.
Grabež, Nedjelko Čabrinović, and Gavrilo Princip, were all suffering from tuberculosis and knew they would not live long and the other four men hated Franz Ferdinand. They were therefore willing to give their life for what they believed was a great cause: Bosnia and Herzegovina achieving independence from Austro-Hungary.
Nikola Pašić, the prime minister of Serbia, heard about the plot and gave instructions for Grabež, Princip and Čabrinović to be arrested when they attempted to leave the country. However, his orders were not implemented and they managed to reach Bosnia and Herzegovina where they joined forces with fellow conspirators, Vaso and Veljko Čubrilović, Muhamed Mehmedbašić, Danilo Ilić and Cvijetko Popović.