The opening months of the First World War marked the termination of two hundred years of a style of infantry fighting which, with decreasing logic, t… - John Keegan

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 any point during the five weeks of crisis that preceded the first clash of arms, had prudence or common goodwill found a voice; tragic because the consequences of the first clash ended the lives of ten million human beings, tortured the emotional lives of millions more, destroyed the benevolent and optimistic culture of the European continent and left, when the guns at last fell silent four years later, a legacy of political rancour and racial hatred so intense that no explanation of the causes of the Second World War can stand without reference to those roots.

Consequences, of course, cannot be foreseen. Experience can, by contrast, all too easily be projected into the future. The experience of the early warriors of 1914–18 – the probability of wounds or death, and circumstances of squalor and misery – swiftly acquired inevitability. There is mystery in that also. How did the anonymous millions, indistinguishably drab, undifferentially deprived of any scrap of the glories that by tradition made the life of the man-at-arms tolerable, find the resolution to sustain the struggle and to believe in its purpose? That they did is one of the undeniabilities of the Great War. Comradeship flourished in the earthwork cities of the Western and Eastern Fronts, bound strangers into the closest brotherhood, elevated loyalties created within the ethos of temporary regimentality to the status of life-and-death blood ties. Man whom the trenches cast into intimacy entered into bonds of mutual dependency and sacrifice of self stronger than any of the friendships made in peace and better times. That is the ultimate mystery of the First World War. If we could understand its loves as well as its hates, we would be nearer understanding the mysteries of human life.

The system of communication itself denied any rapidity, let alone instantaneity, of communication when it was most needed, which was in the heat of action. The most important of the novelties of modern warfare in our own time has been the development of surveillance, targeting and inter-communication in real time, which is to say at the speed at which events unroll.