World War I started because teenaged Serbian, Gavrilo Princip shot Archduke Franz Ferdinand and his wife dead near Latin Bridge on June 28th, 1914. An Archduke is the son of the emperor of Austria, which was why it was such a huge deal. The reason that Princip shot Ferdinand was so that he could split Austria-Hungary and make a new country, Yugoslavia. Gavrilo was 1 of 6 assassins (five of which were Serbians including Princip.) in a Black Hand Society.
A basic explanation would be saying that Austria got really mad after the Archduke was shot and Austria declared war.
A basic explanation would be saying that Austria got really mad after the Archduke was shot and Austria declared war.