In military history we have a guide by which, if we lack personal experience in war, we can test the results of our reflections and of our experience on the drillground. Military history moreover enables us to appreciate those controlling factors which, in map problems, do not appear at all, and which, in exercises on the terrain, appear only in a restricted measure. One must learn the conduct of war from the experience of others; one’s own experience is costly and is almost invariably gained too late. That experience in war, of itself, is not sufficient (aside from the fact that it is gained too late in a given case) is illustrated by the defeat of the Austrians in 1866, of the French in 1870-71, and of the British in South Africa. “_Les Autrichiens_,” says Colonel Foch,[13] “_ont fait la guerre sans la comprendre, les Prussiens l’ont compris sans la faire, mais ils l’ont étudiée._” “Military history is neither a compilation of clever theories nor a book designed for whiling away idle moments. It is, on the contrary, a careful teacher, who, if we are attentive, allows us to view and grasp matters which we have never before been in a position to see, but which, nevertheless, are liable to confront us in the same, a similar, or a changed form, and demand unpremeditated, instant and decisive action, entailing heavy responsibilities. Military history, it is true, offers us, in the first instance, only events and their outline, conditions and phenomena, but it also presents, what the cleverest theory is unable to furnish, a graphic illustration of the disturbing elements in war, an illustration of the influences, doubts, embarrassments, unforeseen accidents, surprises and delays. It describes the course pursued by commanders and by practical military common sense in surmounting these difficulties. It prepares in advance the mental balance necessary at the moment of action; it should prepare also for the unexpected. It affords a substitute for lack of military experience, for the accumulation of which the life of the individual, prior to the moment of action, has been too short.”[14] The pedantic enumeration of a few examples in support of a stated opinion cannot suffice. It should not be difficult to find examples from military history in support of any opinion; frequently even an incorrect tactical contention can be vindicated by such examples. For in war the action taken is as often wrong as correct; the scales are turned by factors which in most cases appear indistinctly or not at all. The experiences of military history must, therefore, only be used with caution if tactical lessons are to be drawn from them. “A mere allusion to historical events,” says Clausewitz in his chapter on examples, “has the further disadvantage that some readers are either not sufficiently acquainted with these events, or remember them too imperfectly to enter into the author’s ideas, so that such students are compelled to accept