Cause: It all happened because of one simple event that occurred in 1914. This group called the black hand were planning on killing the archduke because he was going to be the Austro-Hungarian Empires emperor. The members of the black hand heard that the archduke was in Sarajevo, Bosnia and Herzegovina. They failed to kill him, but soon there was a member from the black hand named Gavrilo Princip in a nearby deli.
