The assassination of Archduke Franz Ferdinand on June 28, 1914, set off a chain reaction of events leading to World War I. This pivotal moment escalated tensions between European powers, triggering a web of alliances and hostilities. Following the assassination, Austria-Hungary issued an ultimatum to Serbia, and with Russia's support for Serbia, the conflict quickly expanded. The war involved multiple nations and alliances, ultimately leading to a devastating global conflict that redrew borders, created new nations, and had lasting political, social, and economic consequences in the years that followed.