How did the assassination of Archduke Franz Ferdinand in Sarajevo contribute to the outbreak of World War I?

The assassination of Archduke Franz Ferdinand in Sarajevo on June 28, 1914, served as the immediate catalyst for World War I. The act was carried out by Gavrilo Princip, a member of a revolutionary group supported by the Black Hand, who sought to end Austro-Hungarian rule in the Balkans.123

For the Austro-Hungarian government, the assassination provided a long-sought pretext to resolve the perceived "Serbian danger" through military force. With the promise of support from Germany, Austria-Hungary issued a deliberately provocative ultimatum to Serbia on July 23, 1914. Although Serbia accepted most terms, it rejected demands that would have compromised its sovereignty, leading Austria-Hungary to sever diplomatic relations and declare war on July 28.432

This localized conflict rapidly escalated into a global war due to the complex web of European alliances. Russia’s mobilization to support Serbia triggered counter-mobilizations, drawing in Germany, France, and eventually Great Britain, as the major powers were bound by their respective treaty obligations and strategic military plans.243