The major conflict sparked by the assassination of Archduke Francis Ferdinand was World War I. Ferdinand, heir to the Austro-Hungarian throne, was assassinated on June 28, 1914, in Sarajevo by nationalist Gavrilo Princip, a member of the Serbian nationalist group known as the Black Hand. His assassination set off a chain reaction of events, leading Austria-Hungary to issue an ultimatum to Serbia. The ensuing escalation of alliances and military mobilizations resulted in the outbreak of the war in July 1914, eventually drawing many nations into one of the deadliest conflicts in history, with significant geopolitical repercussions.