Sarajevo was in Bosnia, the province that - to Serbia's anger - had been annexed by Austria-Hungary in 1908.
Archduke Franz Ferdinand was heir to the throne of Austria-Hungary. He was inspecting the army in Sarajevo with his wife Sophie. The royal couple arrived by train at 9.28am.
Seven young Bosnian Serbs planned to assassinate Franz Ferdinand as he drove along the main road in Sarajevo, the Appel Quay.
The first conspirator who tried to kill Franz Ferdinand threw a bomb at his car. He missed and was arrested.
The Archduke escaped unhurt. He decided to abandon the visit and return home via a different route to the one planned.
No one had told the driver the route had changed. On the way back, therefore, the driver turned into Franz Josef Street, following the published route and, when told of his error, stopped the car to turn around.
Unfortunately, the car stopped in front of Gavrilo Princip, one of the conspirators, who was on his way home thinking he had failed. Princip pulled out a gun and shot at Franz Ferdinand, hitting him in the jugular vein. There was a tussle, during which Princip shot and killed Sophie. By 11.30am, Franz Ferdinand had bled to death.