http://www.dailymail.co.uk/news/article-2576335/How-Germany-crucified-Hidden-100-years-astonishing-images-German-soldiers-haunted-spectre-defeat-paying-ultimate-price-captured-camera-one-brothers-arms.html
Officially triggered by a Bosnian Serb named Gavrilo Princip killing an Austrian Duke and his wife, not that anybody cared.
