What were the main reasons of world war 1?

Answer 1

Following increasing tensions in Europe due to the Tangiers and Agadir crises the sides had been diplomatically decided for quite some time. France and Britain had signed the entente cordiale some years before the outbreak of war in 1904. Germany was becoming increasingly isolated diplomatically with the view also being that large contiguous land empires had seen their day. Germany saw this and wanted a large colonial empire stretching across the sealanes of the world. She was a bit late off the mark since the British and French Empires had been scrambling over each other for colonies since the 16th century and therefore it seemed highly threatening that Germany should wish to challenge British seapower which they did by attempting to outbuild Britain in dreadnought class ships.

Britain was relatively stretched by this since they wanted to maintain the "two power standard." I.e. having more ships than the next two most powerful navies combined.

France was also bitter for having lost the province of Alsace-Lorraine to Germany when they were soundly thrashed in the Franco-Prussian in 1870. They simply wanted this back.

The rise of nationalist movements should by no means be seen as a novel thing here (look at America, France, Holland etc) but it was certainly the spark which lit the tinder. The burgeoning nationalist movements in the Habsburg empire resulting in the shooting of archduke Franz Ferdinand in Sarajevo were those that lead to the actual diplomatic decelerations of war firstly by Austria-Hungary against Serbia and then allies of Serbia against allies of Austria-Hungary.

The tensions had been building for a while it was by no means one single factor