Gavrilo Princip
From Tardis Wiki, the free Doctor Who reference
Gavrilo Princip was a Serbian terrorist who assassinated Archduke Franz Ferdinand of Austria-Hungary, the heir to the Austrian throne, on 28 June 1914.
Prinzip killed the Archduke in protest of Austria's claims on Sarajevo and the rest of Bosnia, territories the Serbs believed were rightfully theirs. (PROSE: Human Nature)
Ferdinand's death led directly to the First World War, "through nations having treaties with nations", according to the Tenth Doctor. (TV: The Family of Blood)
