July Crisis: Austria-Hungary issues a series of demands in an ultimatum to the Kingdom of Serbia demanding Serbia to allow the Austrians to determine who assassinated Archduke Franz Ferdinand. Serbia accepts all but one of those demands and Austria declares war on July 28.

The July Crisis was a series of interrelated diplomatic and military escalations among the major powers of Europe in mid-1914, which led to the outbreak of World War I. It began on 28 June 1914 when the Bosnian Serb nationalist Gavrilo Princip assassinated Archduke Franz Ferdinand, heir presumptive…