Plans made without allowance for the intentions of the enemy are liable to miscarry. So it was to prove in… — John Keegan

All worked excellently, until fighting began.

The basic and stark fact, nevertheless, was that the conditions of warfare between 1914 and 1918 predisposed towards slaughter and that only an entirely different technology, one not available until a generation later, could have averted such an outcome.

The first day of the battle of the Somme, 1 July 1916, was to be an awful demonstration of that truth.

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.