Do it properly, or face the firing squad at dawn!
Franz Ferdinand, heir to the Austro-Hungarian empire, goes to inspect his troops in Sarajevo, Bosnia. He makes sure that their uniforms are done properly.
Meanwhile, in the garden of a patisserie, the black hand gang are preparing to assassinate Franz Ferdinand and his wife for mistreating their country. Each of the seven members have sworn an oath to keep the gang a secret, and with 19 year old Gavrilo Princip as their leader, they believe they will succeed.
Each member lines up along the road that Franz Ferdinand is driving down. One member throws a bomb, but it has a 10 second delay and Ferdinand deflects it away from the car.
Ow, that really hurt!
Failing the assassination, Princip gets a sandwich. Afterwards, the driver of the car takes a wrong turn, leading the archduke straight into the path of Princip. Princip takes one look at him and shoots his neck.
All but one member of the gang are tracked down, and all but one of the captured stick to the oath of secrecy. However, the one member who doesn't, produces valuable information such as the fact that the firearms were provided by the Serbian government. This man is later hanged along side the others over the age of 20. Those below that age, including Princip, had long prison sentences.
With the information they have about the firearms, the Austro-Hungarian empire declares war on Serbia. This provokes all of Serbia's allies to declare war on Austria-Hungary, and all of Austria-Hungary's allies to declare war on Serbia, starting World War 1.