As reported quite widely, 28 June 2014 (Saturday) marked the centenary of the assassination of Archduke Franz Ferdinand and his wife in Sarajevo by Gavriol Princip. I am no historian, but while this may have been one of the events in the lead up to World War 1, it was by no means the only factor involved, as discussed here and also here.
For Serbs, the day is also of significance, as it is Vidovdan. (St Vitus Day) .
Plaque marking the spot from which the shot was fired