What assassinated in Sarajevo that sparked the start of World War 1.?

The assassination of Archduke Franz Ferdinand of Austria and his wife, Sophie, in Sarajevo on June 28, 1914, sparked the start of World War I. The couple was killed by Gavrilo Princip, a member of the nationalist group known as the Black Hand, which sought to promote Serbian nationalism. This act set off a chain of events, including Austria-Hungary's declaration of war against Serbia, which ultimately led to the involvement of multiple countries and the escalation into a global conflict.