(3) How did the hostility between Austria and Serbia lead to the outbreak of War

encouraged Slav people in Austria to seek independence and sponsored secret society “Black Hand” to launch terrorist activities.  Austria saw Serbia as greatest troublemaker and military plans were made to destroy Serbia.After the first Balkan War, a new state Albania was created on suggestion of Austria to block Serbia’s path to Adriatic Sea. This increased tension between Austria and Serbia. After the Balkan Wars, Serbia became the biggest winner; her size of territories doubled and emerged as the leading Balkan power that posed a threat to Austria.On 28 June 1914, Archduke Franz Ferdinand, heir to the Austrian throne was shot dead by Gavrilo Princip of the Black Hand at Sarajevo, the Bosnian capital.On 5 July, 1914, Germany assured Austria that should there be an Austro-Serbian war, Germany would give Austria unlimited support as an ally.On 23 July 1914, Austria sent an ultimatum to Serbia and demanded Serbia to indemnify, apologize, admit responsibility, punish people involved in the assassination and suppress all anti-Austrian societies in the presence of Austrian officials.On 25 July, Serbia accepted most terms but not the last demand for if infringed her sovereignty.On 28th July, Austria declared war on Serbia. Austrian troops marched into Serbia and bombarded Belgrade.On 29th July, Russian knew that it she failed to defend Serbia, she could no longer set her foot on the Balkans as the leader to the Slav nations. She then ordered troops to mobilize in support of Serbia..On 30 July, Germany feared she would face a two-front war and sent an ultimatum to Rus demanding her to demobilize on 30th.Rus refused and Ger declared war on Rus on 1 Aug. France mobilized in support of Russia.On 4 Aug. German declared war on France.  Ger invaded France through Belgium according the Schlieffen Plan.On the same day, Britain sent ultimatum to German to stay away from Belgium which was a neutral country.   When it was ignored, Britain declared was on Germany.The hostility between Austria-Hungary and Serbia set off the Austro-Serbian War and it also led to the involving of all the great powers in a general war, WWI.