The assassination of Archduke Franz Ferdinand in 1914 was a pivotal moment that triggered World War I. The heir to the Austro-Hungarian throne was killed in Sarajevo by Gavrilo Princip, a member of the nationalist group known as the Black Hand. This event set off a chain reaction of alliances and militaristic responses among European powers. Austria-Hungary's declaration of war against Serbia led to the mobilization of other nations due to existing alliances, escalating the conflict into a widespread war. The assassination not only marked the beginning of WWI but also significantly altered the political landscape of Europe, ultimately leading to the collapse of empires and the rise of new nations.