The First World War could have been avoided, in 1914.
Had Russia not rushed to the aid of Serbia the war would have ended by December in an embarrassing Austro-Hungarian defeat.
Had Germany not rushed to provide blanket support (the "blank cheque") of Austria-Hungary after Serbia was only 20 minutes late responding to the Austro-Hungarian list of demands the chickenhawks in Vienna would have been forced to sit on some ice, and then, in 1916 when the emperor died, the empire would have fallen apart on its own.
Had Britain not rushed to defend Belgian neutrality against the evils of the Hun (7,000 dead Belgians were worth more to the British than 10 million dead Congolese) the war would have ended in 1914 with a repeat of the Franco-Prussian War 40 years earlier.
The war could have been avoided in at least three different ways. The question is should the war have been avoided? If not 1914 would not another casus belli arisen eventually as two bloated and decrepit empires teetered on the verge of collapse and as Germany would inevitably sought its place in the sun? Was it better to preempt a potentially more disastrous future war by charging into war in 1914?
(Coming in July)