The assassination of which heir to the Austro-Hungarian throne precipitated World War I?

The assassination of Archduke Franz Ferdinand precipitated World War I. Franz Ferdinand was heir presumptive to the Austro-Hungarian throne when Bosnian Serb nationalist Gavrilo Princip shot him and his wife, Sophie, in Sarajevo on 28 June 1914.

The killings triggered the July Crisis. Austria-Hungary, backed by Germany, issued Serbia a severe ultimatum and declared war on 28 July after Serbia’s response was judged insufficient. Russia mobilized to support Serbia; Germany declared war on Russia and France, and Germany’s invasion of Belgium brought Britain into the conflict.

The assassination was the immediate catalyst, not the sole underlying cause. European militarism, imperial rivalry, nationalism and rigid alliance commitments had created a dangerous political environment. Another frequent mistake is calling Franz Ferdinand the emperor: Emperor Franz Joseph I still ruled Austria-Hungary in 1914. Franz Ferdinand was next in line, but he never became emperor.