Conversation so far:
Are there any other interesting aspects about the Franz Joseph I of Autria article?
the assassination of Franz Joseph's  nephew and heir-presumptive, Archduke Franz Ferdinand, in Sarajevo resulted in Austria-Hungary's declaration of war against the Kingdom of Serbia

Question: When did this occur?
Self-contained rewrite: When did  occur the assassination of his nephew and heir-presumptive, Archduke Franz Ferdinand, in Sarajevo that  resulted in Austria-Hungary's declaration of war against the Kingdom of Serbia?