The first of these events was that of the assassination of the Austro-Hungarian Archduke Franz Ferdinand in Sarajevo. This event, coupled with the rising tensions of the time, served as the ultimate catalyst for the war. Following the assassination, Germany promised Austria-Hungary a “blank check”, or really, military support in the event of any action taken against Serbia. Within a month, Austria declares war on Serbia. With the mobilization of Austria, Russia mobilizes to support Serbia. On August 1, 1914, Germany declares war on Russia, and three days later, war against France. On August 4, 1914, Britain declares war, and we have officially begun the First World War.
Many things led Europe to their breaking point: rising tensions between European powers, the hunger for empire, and a number of small scale conflicts led to the conditions in with the First World War would be able to occur. The straw that broke the camel’s back, the series of events that would put World War I into motion were the assassination of Archduke Franz Ferdinand., and the events that followed, acted as the catalyst officially pulling Europe into a continent wide