Throughout the nineteenth century Europe became a tinderbox waiting to be lit. The spark that ignited this tinderbox would be the Archduke Franz Ferdinand, heir to the Austro-Hungarian Empire.
Go 'n' kill him.
Franz was asked to visit the troops in Sarajevo (the capital city of Bosnia) as he was the inspector general of the army. His trip had another motive which was to convince the Bosnians that when he becomes he will be nice to them.
Far away in Serbia, the leader of the black hand gang (a group of terrorists who aim to reunite all the countries that once comprised the Kingdom of Serbia), Api, is planning how to incite the Bosnians into rebellion against the Austro-Hungarian Empire. He plans to do this by having the Archduke assassinated.
Anyway when I become emperor I will be really nice to you.
Api gets seven members of the gang to go and kill him. Gavrilo Princip is the leader of the force. Gavrilo is seriously ill and will die soon. In Serbian culture however, the death of a martyr is very much admired so Gavrilo is willing to die for the cause as are the other six members. Api is also the head of the Serbian military and so can to give them all the weapons they need.
The day before the procession, the paper's published the route which enabled the assassins to line up along the main road that he would take. The Archduke had decided not to take the army and instead go with the police to give a friendly attitude. Also he travelled in an open top car. The first assassin failed. The second assassin threw a bomb but it exploded after the car had gone. The remaining assassins were too startled to react.
When Franz got to the town hall he shouted at the mayor and then gave his speech. Afterwards he wanted to visit the wounded from the explosion and so the driver drove him to the hospital. But on the way the driver took a wrong turn and ended up driving past Gavrilo Princip, who had gone for a sandwich. The car then stalled and stopped in front of the assassin. Gavrilo took his chance and shot both Franz and Sofie. This provoked Austria and Germany to attack Serbia who had allied themselves with Russia, France and the UK.
By dying I gave Europe an excuse to start the Great War (WW1).