The Causes of WW1

Another crisis took place in the Balkans in 1908 over the annexation by Austria-Hungary of Bosnia and Herzegovina. Because one form of Panslavism was a Pan-Serbian or Greater Serbia movement in Serbia, which had as one of its objects the acquisition by Serbia of the southern part of Bosnia, the Serbs threatened war against Austria. War was avoided only because Serbia could not fight without Russian support, and Russia at the time was unprepared for war. …

…initiate war against Germany, instead of the other way around. Although paper declarations of war had been issued earlier and a flotilla of Austro-Hungarian monitors had bombarded Belgrade on July 29, the crossing of the Belgian frontier marks the true beginning of World War I, the point of no return. Since this action was an integral part of German mobilization plans, Germany's decision to mobilize on July 31 was in effect a decision to initiate general war.