How easy it is, in retrospect, to see that that was so, how difficult at the time to except the fallibility of governments and general staffs. The fu… - John Keegan

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

Principle perhaps was at stake; but the principle of the sanctity of international treaty, which brought Britain into the war, scarcely merited the price eventually paid for its protection. Defence of the national territory was at stake also, the principle for which France fought at almost unbearable damage to its national well-being. Defence of the principle of mutual security agreement, underlying the declarations of Germany and Russia, was pursued to a point where security lost all meaning in the dissolution of state structures. Simple state interest, Austria’s impulse and the oldest of all reasons for war-making, proved, as the pillars of imperialism collapsed about the Habsburgs, no interest at all.

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?