June 28, 1914, Gavrilo Princip assassinates Archduke Franz Ferdinand, heir to the Austrian throne, and his wife Sophie, the Duchess of Hohenberg in Sarajevo. July 28, 1914, Austro-Hungarian Empire declares war on Serbia. Over the next several days, things start going from bad to worse. July 29, 1914, Austria-Hungary commenced firing artillery on Belgrade. July 30, Russia mobilizes its armies. August 1, Germany declares war on Russia. August 3,...