Origins of World War One

Some of the causes of the start of World War One are: 

• 1.The growth of nationalism across Europe
• 2. Tensions over territory in the Balkans. Austria-Hungary competed with Serbia and Russia for territory and influence in the region and they pulled the rest of the Great Powers into the conflict through their various alliances and treaties.
• 3. The assassination of Archduke Franz Ferdinand of Austria and his wife by Gavrilo Princip
• 4. Imperialism
• Some people would even say that Germany and Austria-Hungary (the Central Powers) are seen, at the very least, as creating the conditions for conflict.
• Some go much further, blaming Germany for planning and waging a deliberate war of aggression.
• Under Kaiser Wilhelm II, Germany moved from a policy of maintaining the status quo to a more aggressive stance. He decided against renewing a treaty with Russia, effectively choosing  for the Austrian alliance. Germany's western and eastern neighbors, France and Russia, signed an alliance in 1894 united by fear and resentment of Berlin.
• Also many of the commanders in the war(both sides) thought the war would be over in less than six months

      http://www.bbc.co.uk/history/worldwars/wwone/origins_01.shtml