The two categories, however, although convenient for discus sion, can never be truly divided into separate compartments be cause each not only influences but merges into the other. Nor has clear thought been assisted by the attempts to subdivide into, or to bridge the indefinite dividing line by, fresh categorical defini tions. First among these was the term "grand tactics," which came into use in the late 18th century to express the combina tion and movements of forces preparatory to, and in readiness for, the battle. This term likewise has undergone changes of meaning, and is often employed to denote the plan upon which the applica tion of force, as distinct from other agencies, is to be based. It embraces the combined use of armies, navies and now air forces, but excludes economic or political instruments.
A term which fills a greater need, and is less productive of confusion, is that of "grand strategy." If practically synonymous with the policy which governs the conduct of war, as distinct from the permanent policy which formulates its object, the term "grand strategy" serves to bring out the sense of "policy in execu tion." For the role of grand strategy is to co-ordinate and direct all the resources of a nation towards the attainment of the politi cal object of the war—the goal defined by national policy.
Grand strategy should both calculate and develop the economic resources and man-power of the nation in order to sustain the fighting services. So also with the moral resources—for to foster and fortify the will to win, and to endure, is as important as to possess the more concrete forms of power. And it should regu late the distribution of power between the several services, and between the services and industry. Nor is this all, for fighting power is but one of the instruments of grand strategy. It should take account of and apply the power of financial pressure, diplo matic pressure, commercial pressure, and, not least, ethical pres sure to weaken the opponent's will. A good cause is a sword as well as a buckler. Furthermore, while the horizon of strategy is bounded by the war, grand strategy looks beyond the war to the subsequent peace. It should not only combine the various instru ments, but so regulate their use as to avoid damage to the future state of peacefulness, secure and prosperous. Little wonder that, unlike strategy, the realm of grand strategy is for the most part terra incognita! Pure Strategy.—Having cleared the ground, we can build up
our conception of strategy on its original and true basis—that of "the art of the general." This depends for success, first and most, on a sound calculation and co-ordination of the end and the means. The end must be proportioned to the total means, and the means used in gaining each intermediate end which con tributes to the ultimate must be proportioned to the value and needs of that intermediate end—whether it be to gain an objec tive or to fulfil a contributory purpose. An excess may be as harmful as a deficiency. A true adjustment would establish a perfect economy of force, in the deeper sense of that oft-distorted military term. But, because of the nature and uncertainty of war, an uncertainty aggravated by its unscientific study, a true adjust ment is beyond the power of military genius even and success lies in the closest approximation to truth. This relativity is inher ent because however our knowledge of the science of war, at pres ent an almost unexplored region, be extended, war is a science which depends on art for its application. Art can not only bring the end nearer to the means, but by giving a higher value to the means enable the end to be extended. This complicates calcula tion, because no man can exactly calculate the capacity of human genius and stupidity nor the incapacity of will.
Surprise lies in the psychological sphere and depends on a calcu lation, far more difficult than in the physical sphere, of the mani fold conditions, varying in each case, which are likely to affect the will of the opponent.