Complex sentence: In 1914 Gavrilo Princip assassinates Franz Ferdinand in Sarajevo which starts World War I. The Kingdom of Austria and Hungary declares war on Serbia, and the Austrians begin to incite the non-Serbian population of Višegrad against the Serbs living in the town.
Split into simpler sentences: In 1914 Gavrilo Princip assassinates Franz Ferdinand in Sarajevo and thus causes the First World War. Austria-Hungary declares war on Serbia, and the Austrians begin to incite the non-Serbian population of Višegrad against the Serbs living in the town.