The assassination of Archduke Franz Ferdinand occurred on June 28, 1914, in Sarajevo and is widely considered the catalyst for World War I. The heir to the Austro-Hungarian throne was killed by Gavrilo Princip, a member of the nationalist group known as the Black Hand. This event exacerbated existing tensions in Europe among nations and alliances, ultimately leading to the declaration of war. The assassination triggered a series of political responses, including Austria-Hungary's ultimatum to Serbia, which spiraled into a full-blown conflict involving multiple nations within weeks.