The conflict sparked by the assassination of Archduke Franz Ferdinand in 1914 was World War I. The Archduke, heir to the Austro-Hungarian throne, was assassinated in Sarajevo on June 28, 1914, by a Bosnian Serb nationalist, Gavrilo Princip. This act set off a chain reaction of alliances and hostilities between major powers in Europe. Austria-Hungary declared war on Serbia, leading Russia to mobilize in defense of Serbia. Subsequently, Germany, allied with Austria-Hungary, declared war on Russia, and France and the United Kingdom joined the fight against the Central Powers, escalating into a global conflict that lasted until 1918.