-
Tension between Austria-Hungary and Serbia exploded when the archduke of Austria-Hungary Franz Ferdinand was assassinated by a Serbian nationalist Gavrilo Princip during Ferdinand's visit to Sarajevo.
-
After Princip was arrested and identified as a Serbian, the Austro-Hungarian Empire decided to use it as an excuse to punish the Serbians by making humiliating demands of the Serbians before finally declaring war on Serbia.
-
Quickly after Austria-Hungary declared war on Serbia, as an ally of Serbia, Russia decided to declare war on Austria-Hungary as well. In response to Russia's action, Germany, as an ally of Austria-Hungary, also declared war on Russia.
-
After declaring war on Russia, Germany decides to declare war on Russia's ally France as well. As a result, Germany now had a war on two fronts.
-
In order to have access to France, Germany decides to invade Belgium because it was located between Germany and France.
-
Germany's invasion of a neutral country, Belgium, angered Great Britain and it then declared war on Germany. The major participants of World War I were now engaged in battle.
