The two events, of course, are causally connected. But how? Why did the death of the heir to the Austrian Empire lead to World War? If you've ever pondered on such things, and if you're knowledge of the facts is hazy, here's my brief guide to the Great War.
1. Bosnia, 100 years ago today, was part of the Austro-Hungarian empire and the assassination was part of a campaign for independence;
2. Austria was a long-standing ally of Germany and when it finally got round to responding to the events in Sarajevo, it made sure it did so with Germany's complete support (the so-called 'blank cheque);
3. The problem was the Russians. Both Austria and Germany feared Russian involvement in any fighting in Serbia, and they were right.
4. On August in response to Austria's declaration of war on Serbia (basically, punishment for the assassination of the heir to the throne) Russia mobilised its army;
5. This meant France was now committed thanks to a mutual assistance treaty with Russia to fight against Germany;
6. Which led to the enactment of the Schleiffen Plan by Germany - invading France through Belgium and having a pop at the Russians through Poland.
Which is basically where World War One begins. See? It's not really that difficult is it? Meanwhile, over in the Balkans, Austria-Hungary was indeed fighting in Serbia, the Turks became involved and the Italians, Bulgarians too ultimately and the whole thing went to hell.