Assassination at Sarajevo
28 June 1914 Archduke Franz Ferdinand visits Bosnian capital Sarajevo.
A group of serbian terrorists, the Black Hand Gang planned to kill him to publisice their anger at Bosnia being part of Austria-Hungary.
The first attempt was unsuccsesful - a grenade was thrown but exploded in the car behind the Archdul, injuring several people.
Franz Ferdiand continued the visit and insisted on visting the wounded in hospital.
On leaving the hospital the driver of the car took a wrong turning, as he stopped to reverse one of the waiting assassins, Gavrilo Princip, fired two shots.
One hit the Archduke, the second hit his wife Sophie.The Archduke's wife died instantly and he died on the way to hospital.
Such a murder would usually have been a matter for the two countries alone. But relations between the alliances of the great powers were so strained that it lead to the outbreak of WW1...
from assassination to war 
the Austrian government issued an ultimatum to Serbia to comply with 10 conditions, even though they have no proof that the Serbian government were involved.
The Serb reply indicated that they didn't want to go to war. They were prepared to accept help from Austria-Hungary in getting rid of all the Societies in Serbia.
However they did not accept 1 point because it involved delegates from Austria Hungary entering the imquiry.
This would mean a foreign influence in Serbian courts. This would be a threat to Serbian independence. The Serbian government stressed that it would prefer the case to be refered to an international court.
The Black Hand Group was not associated with the Serbian government so they could see no reason for Austria-Hungary to declare war.
Russia was determined to support its slav allies this time. On 30 July the Russians mobilised their army and prepared for war.(they did this without consulting Britain and France)
Germany supported Austria-Hungary by declaring war on Russia on 1 August and two days later went to war with France
from assassination to war...
At this stage Britain were keen to aviod involvement in the war. Britain would remain neutral unless the Germans attacked the north coast of France.
On 3 August the Germans launched the Schlieffen Plan. This was an attack on France through Belgium.
The invasion of Belgium brought Britain into the war. Britain had guaranteed Belgium's neutrilaty at the treaty of london.
Britian stood by this agreement.
In August 1914 all members of the rival alliance systems, except Italy, declared war on each other.
The outbreak of war was a series of crises and mistakes.
Events before 1914 had pushed the Great Powers towards war; events after sarajevo sparked off the war.