The American Civil War had revealed the influence not only of the development of railways upon strategy, but of changing economic conditions, but its embryonic lesion was largely obscured by the war of 187o in Europe. Here inferiority of force and stupidity of mind so weighted the scales against the French that a quick military decision was obtained. The World War (q.v.) and its strategical lessons are discussed in detail elsewhere.
Reflection suggests, and history confirms, that a direct approach is the worst of all military "risks"—worse than the passage of mountains, deserts or swamps, worse than that of cutting oneself loose from one's supplies or of operating with inferior force. Natural hazards, however formidable, are inherently less dangerous and uncertain than fighting hazards. For all condi tions are more calculable, all obstacles more surmountable than those of human resistance. By reasoned calculation and prepara tion they can be overcome almost "to time-table." It was Clausewitz who, reacting against the "geometrical" in terpretation of Napoleon's strategy, laid down that "the inde pendent will-power of his opponent" is the least calculable and most formidable of the factors with which a commander has to deal. But his line of thought and teaching led him to place excessive emphasis on force applied through the bodies of a corn mander's troops as the means of damaging the commander's will. It is curious that he should have neglected the heightened power and speed of impressions made immediately on the opposing com mander's mind, in favour of impressions made through a "third party" channel. But the teaching of Clausewitz was directed more to fortify the will of the commander on his own side than to under mine the will of the opposing commander. And he was a cultivator of expectancy, rather than an exponent of the unexpected.
Hence force overshadowed surprise and mobility on the strate gical horizon of the 19th and early loth centuries. Hence the relative neglect not only of psychological surprise but of new inventions which might contribute to it. So also with mobility— rate of movement was treated as an invariable factor. In staff rides and exercises, calculations and plans were based on "normal" times, and little research was made into the advantages of un expected acceleration by new means or by a partial sacrifice of strength and convenience. In contrast to Napoleonic practice, undue stress was laid on the importance of bringing a force entire to its destination—tying it to the pace of its slowest elements. Equally neglected was the lesson contained in Napoleon's marche de manoeuvre—guns and trains upon the road, infantry and cav alry moving across country. Even since the World War, although
the strategic value of tanks and the newer forms of transport lies as much or more in their power of cross-country movement as in their speed, the strategic advantages of such movement are rarely applied or realized. This failure of comprehension is perhaps the less surprising when, in studying the history of the past hundred years, we see the failure of strategists to grasp the idea underlying Napoleon's use of the divisional system. By 1870 the intervals had become much narrower and by 1914 armies were back in the old solid block, with the divisions rubbing shoulders in a long, inflexible, unmanoeuvrable, line. Yet all the time the increasing range of weapons had progressively diminished the risk and increased the profit of leaving intervals—of a calculated distribution of force for a concentrated purpose. For the divi sional organization was by its nature a fresh aid to the strategy of indirect approach, whose psychological purpose may be epito mized in the one word "trap"—the trap being most often baited by a military move directed against an economic target—the sources of supply of the opposing state or army. The future is likely to strengthen this experience, for national conditions and the development of civilization are bringing new influences to bear on strategy and opening to strategy new channels of influence. These were foreshadowed in the American Civil War.
To overthrow the enemy's armed forces may still be the quickest and most effectual way to cause the collapse of the enemy nation's will to resist. But the new civil conditions pro vide a far stronger argument against attempting it unless the military conditions are highly favourable to its success. The civil conditions give the strategist not only an alternative channel of action but an additional lever towards his military aims. By threatening economic objectives he may be able both to distract and dislocate the enemy's military dispositions, while the greater frequency and sensitiveness of such civil objectives may give him opportunities to slip past the military shield and strike at them with decisive results. This potential development of strategy is greatly favoured by the advent of the air weapon, which introduces a third dimension of movement. Metaphorically, the effect may be defined as the replacement of a "draughts-board" theatre of war by a "halma-board"—for aircraft have the power of "hopping over" resistance. (B. H. L. H.) BIBLIOGRAPHY.-Among a host of books the following may be se lected as illustrating the thought of different periods and schools: The Chinese Book of War; Machiavelli, Dell' arte Della Guerra; Jomini, Précis de Part de la Guerre; Clausewitz, vom Kriege; Willisen, Theorie les Grossen Krieges; Moltke, Taktisch-strategische Aufsiitze; Colin, Les Transformations de la Guerre; Bloch, La Guerre; Fuller, The Foun dations of a Science of War; Liddell Hart, The Decisive Wars of His tory. Any general survey should be supplemented by the study of good military biographies, but they are rare.