The major world event sparked by the assassination of Archduke Franz Ferdinand was the outbreak of World War I in 1914. The assassination, committed by Gavrilo Princip, a nationalist from Serbia, ignited longstanding tensions between the Austro-Hungarian Empire and Serbia, leading Austria-Hungary to declare war on Serbia. This declaration activated a complex web of alliances, drawing in major powers like Germany, Russia, and France and escalating the conflict into a global war. The resulting hostilities resulted in significant loss of life, profound social change, and ultimately reshaped international relations for decades to come.