The Great War caused the direct sacrifice of eight million lives, to which the British Isles alone contributed three-quarters of a million. So ineffectual was the treatment prescribed by the military practitioners who were called in that the illness took over four years to run its course, during which the financial temperature mounted daily, until for this country alone it reached a cost of £8,000,000 a day. Our total war expenditure was nearly ten thousand million pounds; our National Debt has been increased tenfold. Moreover, these long years of strain and want so impaired the physical health of the peoples that they fell an easy prey to epidemic diseases, and the influenza scourge of 1918 and 1919 cost, among the civilian population of the world, more than twice as many lives as were lost in battle. It is surely clear that any further wars conducted on similar methods must mean the breakdown of Western civilization. Is there an alternative? To answer this question the obvious course is to ascertain what were the foundations on which the military leaders of the Great War built their doctrine of war, and then to examine these in the light of reason and experience――as embodied in history. The traditional military mind is notoriously sensitive to any breath of criticism, and any attempt to tear aside the veil of its _mystery_ is apt to be greeted by the cry of “sacrilege.” Occasionally some daring soldier has done so――and has paid the penalty for exposing to lay eyes the emptiness of the shrine. Thus Marshal Saxe in his eighteenth-century _Reveries_ on the art of war, declared that “custom and prejudice confirmed by ignorance are its sole foundation and support,” for which temerity Carlyle, the disciple and mouthpiece of the Frederician dogmas, poured scorn on his book as “a strange military farrago, dictated, as I should think, under opium.” Similarly, a generation before the Great War, Monsieur Bloch, the civilian banker of Warsaw, forecast its nature with extraordinary prescience, only to be ridiculed by the General Staffs of Europe. Yet the stalemate that he predicted would arise from the clash of “nations in arms” came true――with the sole difference that he underestimated the blind obstinacy of the leaders and the passivity of the led in continuing for four more years to run their heads against a brick wall. Now, however, in these post-war years of disillusionment, is the time to take stock of the exorbitant cost of the war in lives and money, of the moral and economic exhaustion that is its fruit. Though professional experience in any department of life is the way to executive skill, concentration on technical problems has a notorious tendency to narrow the vision. Hence, while paying tribute to the professional ability shown in the later phases of the 1918 campaign, we are justified, standing amid the _débris_, in questioning the strategic aim and direction of the war.