<Li> July 25: Serbia responds to Austro - Hungarian démarche with less than full acceptance and asks that the Hague Tribunal arbitrate . Austria - Hungary breaks diplomatic relations with Serbia . Serbia mobilizes its army . </Li> <Li> July 26: Serbian reservists accidentally violate Austro - Hungarian border at Temes - Kubin . </Li> <Li> July 26: A meeting is organised to take place between ambassadors from Great Britain, Germany, Italy and France to discuss the crisis . Germany declines the invitation . </Li> <Li> July 28: Austria - Hungary, having failed to accept Serbia's response of the 25th, declares war on Serbia . Austro - Hungarian mobilisation against Serbia begins . </Li>

The event igniting world war i occurred in what part of the world