The Causes of World War One

The Causes of World War One
June 28 in Sarajevo
We'll start with the facts and work back: it may make it all the easier to understand how World War One actually happened.   The events of July and early August 1914 are a classic case of "one thing led to another" - otherwise known as the treaty alliance system.
The explosive that was World War One had been long in the stockpiling; the spark was the assassination of Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, in Sarajevo on 28 June 1914.   (Click here to view film footage of Ferdinand arriving at Sarajevo's Town Hall on 28 June 1914.)
Ferdinand's death at the hands of the Black Hand, a Serbian nationalist secret society, set in train a mindlessly mechanical series of events that culminated in the world's first global war.
Austria-Hungary's Reaction
Austria-Hungary's reaction to the death of their heir (who was in any case not greatly beloved by the Emperor, Franz Josef, or his government) was three weeks in coming.   Arguing that the Serbian government was implicated in the machinations of the Black Hand (whether she was or not remains unclear, but it appears unlikely), the Austro-Hungarians opted to take the opportunity to stamp its authority upon the Serbians, crushing the nationalist movement there and cementing Austria-Hungary's influence in the Balkans.
It did so by issuing an ultimatum to Serbia which, in the extent of its demand that the assassins be brought to justice effectively nullified Serbia's sovereignty.   Sir Edward Grey, the British Foreign Secretary, was moved to comment that he had "never before seen one State address to another independent State a document of so formidable a character."
Austria-Hungary's expectation was that Serbia would reject the remarkably severe terms of the ultimatum, thereby giving her a pretext for launching a limited war against Serbia.
However, Serbia had long had Slavic ties with Russia, an altogether different proposition for Austria-Hungary....