The First World War was a tragic and unnecessary conflict. Unnecessary because the train of events that led to its outbreak might have been broken at… - John Keegan

War’s rancours are quick to bite and slow to heal.

But then the First World War is a mystery. Its origins are mysterious. So is its course. Why did a prosperous continent, at the height of its success as a source and agent of global wealth and power and at one of the peaks of its intellectual and cultural achievement, choose to risk all it had won for itself and all it offered to the world in the lottery of a vicious and local internecine conflict? Why, when the hope of bringing the conflict to a quick and decisive conclusion was everywhere dashed to the ground within months of its outbreak, did the combatants decide nevertheless to persist in their military effort, to mobilise for total war and eventually to commit the totality of their young manhood to mutual and existentially pointless slaughter?

All European armies in 1904 had long-laid military plans, notable in most cases for their inflexibility. None was integrated with what today would be called a ‘national security policy’, made in conclave between politicians, diplomats, intelligence directors and service chiefs, and designed to serve a country’s vital interests, for such a concept of national leadership did not then exist. Military plans were held to be military secrets in the strictest sense, secret to the planners alone, scarcely communicable in peacetime to civilian heads of government, often not from one service to another.