Gavrilo Princip vermoordde op 28 juni 1914 in de Franz-Joseph straat in Serajevo (Bosnië) aartshertog Franz Ferdinand en diens vrouw Sophie.
Samen met zijn kompaan Cabrinovic besloot hij in het begin van 1914 een terroristische aanslag te plegen. ” … two things had crystallized at the beginning of 1914: the choice of Franz Ferdinand as the target and the emergence of a trusted core of plotters from whom the actual assassins would be selected.” Zij recruteerden Princips kamergenoot Trifko Grabez als de derde samenzweerder. “The problem now facing the desperadoes was how to get hold of the necessary instruments of murder and how to be trained to use them … The trio turned initially to yet another of the Bosnian emigrés kicking his heels in the Belgrade coffee houses, one Milan Ciganovic … and, after a few days delay, Ciganovic duly obliged. He had spoken on their behalf, he told them, to an unnamed ‘gospodin’ (or gentleman) and six bombs … as well as four revolvers would be duly provided for the murder plot. They would also be given use of the Serbian underground travel route by which good anti-Habsburg patriots were smuggled in and out of Bosnia across a frontier closely guarded by the Austrian army and police. … The ‘gospodin’ who had been consulted was Major Tankosic, the Serbian army officer who had rejected Princip for his élite band of young guerillas [who were fighting the Turkish army] two years before. And the man whom Tankosic had had to approach in turn was none other than Dragutin Dimitrijevic [die betrokken was geweest bij de moord op de Servische koning Alexander Obrenovic in 1903], now a staff colonel and head of the Serbian military intelligence department. Both men were leading figures in the Serbian secret society ‘Union or Death’, commonly known as the ‘Black Hand’, which had been formed in 1911 out of impatience with the feebleness of the existing Greater Serbia movement. … Revolutionary activity to create a Greater Serbia by any means ‘in all lands inhabited by the Serbs’ was the organization’s prime aim. … After nearly two months of training and planning, [the three conspirators] were ready.” Op 28 mei verlieten zij de Servische hoofdstad aan boord van een stoomboot, die hen over de Sava naar het stadje Sabac bracht. In Sabac gingen zij van boord en vervolgden hun reis te voet, in de richting van de Bosnische grens.
[G. Brook-Shepherd, Victims at Sarajevo (1984), p. 216-220]