Why did World War I break out in the summer of 1914?

The First World War began almost by accident as "the catastrophic result of defective decissions."2 Moreover, "it ended just as strangely and in between it was more destructive than an every war has ever been."10 More British, French and Italian soldiers died in the First World War than died in the second. Finally, "it was the first genuinely global conflict that still shapes out world today in terms of the democracy, nationalism, the international law, and the rights of nations." 10 The origins of this conflict are complex; so are the causes. What then, initiated that "a fate greater than human power hung over Europe"14? How did the greatest conflict in the world begin and what influenced that in 1914, "the nations […] slithered over the brink into the boiling cauldron of war"13? At last, why did the War break out in the summer of 1914?There are different theories that state the causes of the First World War.

The end of Austria-Hungary after the Paris Treaty.

The Schlieffen Plan, emphasizing maneuver and enve...

English: A 1914 British postcard showing the Briti...

The liberal interpretation utters that the First World War is largely caused by the actions of Kaiser Wilhelm II of Germany, who endeavours to make Germany a major imperial power with the best navy and army, while the Risk Theory says that a part of a naval race that was caused by Germany's will to be powerful enough to threat Britain and to make it stay in the port, rather than risk being badly damaged in case of battle with the German fleet. There is also the Cup of Coffee Theory, where history is the result of things, events or coincidences like the assassination of the Austro-Hungarian heir to the throne that was a trigger for the war to break out.

What is more, Archduke Franz Ferdinand's assassination by Gavrilo Princip in Sarajevo on the 28th June 1914 represents Serbian declaration...