On the other hand, it was urged that the fundamental principle of strategy is to concentrate all available forces where the enemy has concentrated his, beat him there, and thus win a victory which will carry with it the desired results in all the subsidiary spheres. Germany once beaten in the West, it was argued, there would be no need to trouble about the Balkans or the amateur strategy which looked to Laibach or Aleppo as the vital spot in the situation. This principle was erected into a dogma, and dogma is a dangerous impediment to the art of war. War is an art, and therefore consists in the adaptation of varying means to conditions which are not constant. Strategy is not, apart from its mechanical adjuncts, a science in which properties are fixed, axioms can be assumed, and the results of experiments foretold; the combination of two armies and a commander-in-chief does not produce the same uniform result as the combination of two parts of hydrogen and one of oxygen; and formulae are as irrational in war as in any other human art. Dogmas deduced from the experience of some wars are inapplicable to others; and the science of wars between France and Germany becomes mere imposture when it seeks to dictate dogma to wars in which the British Empire is involved. The particular dogma about concentration had three defects: it left the initiative to the enemy, thus surrendering the advantage, secured by the command of the sea, of being able to strike in other directions; it assumed that the enemy could be beaten on that front without disturbance on his flanks or in his rear; and it abandoned the Near and the Farther East to any schemes on which the Germans might choose to employ their own or their allies' subsidiary forces.
No one, on the other hand, imagined that the Western front could be denuded of the armies required to maintain it. The question was really how to use the considerable margin of force between what was essential for defence and what was needed for a successful offensive. Should it be employed for frontal attack in the West, or flank attack in the East? Caution counselled one course, adventure suggested the other. Surplus force intended for an offensive on the West would be available, if need arose, for defence; it would not, if it were a thousand miles away, and our needs in the spring of 1918 seemed to supply an effective answer to arguments drawn from our later successes in the Balkans and in Syria. The antithesis is, however, largely a false one, due to the exigencies of popular debate and the habit of treating war as an abstract science independent of changing but actual conditions. No one denies that a diversion of our main effort from France to Laibach in the winter of 1917 would have been fatal to us in the spring of 1918, but it is not clear that the thousands of troops we lost at Loos and the French in Champagne in the autumn of 1915 might not better have been employed in saving Serbia or forcing the Dardanelles.