Complex sentence: On 28 June 1914, the assassination of Archduke Franz Ferdinand of Austria in Sarajevo by Bosnian Serb student Gavrilo Princip precipitated the July Crisis, which led to Austria-Hungary issuing an ultimatum to Serbia on 23 July on suspicion that the assassination was devised in Belgrade.
Split into simpler sentences: On 28 June 1914, Archduke Franz Ferdinand of Austria was assassinated in Sarajevo by Bosnian Serb student Gavrilo Princip. The assassination precipitated the July Crisis, which led to Austria-Hungary issuing an ultimatum to Serbia on 23 July on suspicion that the assassination was devised in Belgrade.