What happened on June 28 1914 and why?

On June 28, 1914, Archduke Franz Ferdinand of Austria was assassinated in Sarajevo by Gavrilo Princip, a member of the nationalist group known as the Black Hand. This event set off a chain reaction of political tensions and alliances in Europe, ultimately leading to the outbreak of World War I. The assassination symbolized the rising nationalist sentiments in the Balkans and highlighted the fragility of international relations at the time. Austria-Hungary's subsequent declaration of war on Serbia escalated the conflict into a full-scale war involving multiple nations.