The second requisite is to know accurately the conditions under which marches by day or night may be 2. Knowledge of the capabilities of the force in moving. performed, and the distances to which they can extend, and not only marches on land, but also voyages by sea.
The third and most important is to have some knowledge of the seasons, and to be able to adapt the design to them.
Nor again is the selection of the ground for the operation to be regarded as unimportant, since it often happens that it is this which makes what seems impossible possible, and what seemed possible impossible.
3. Care in concerting signals.
4. Care in selecting men.Finally there must be no neglect of the subject of signals and counter signals; and the choice of persons by whom and with whom the operation is to be carried out.
[14.] Of these points some are learnt by experience, some from history, and others by the study of scientific strategy. 5. Knowledge of localities. It is a most excellent thing too that the general should have a personal knowledge both of the roads, and the locality which he has to reach, and its natural features, as well as of the persons by whom and with whom he is to act. If that is not possible, the next best thing is that he should make careful inquiries and not trust just any one: and men who undertake to act as guides to such places should always deposit security with those whom they are conducting.
These, and other points like them, it is perhaps possible that leaders may learn sufficiently from the mere study of strategy, 6. Accurate knowledge of natural phenomena enabling a general to make accurate calculation of time. whether practical or in books. But scientific investigation requires scientific processes and demonstrations, especially in astronomy and geometry; the working out of which is not much to our present point, though their results are important, and may contribute largely to the success of such undertakings.
The most important operation in astronomy is the calculation of the lengths of the days and nights. If these had been uniform it would not have been a matter requiring any study, but the knowledge would have been common to all the world: since however they not only differ with each other but also with themselves, it is plainly necessary to be acquainted with the increase and diminution of both the one and the other. How can a man calculate a march, and the distance practicable in a day or in a night, if he is unacquainted with the variation of these periods of time? In fact nothing can be done up to time without this knowledge,—it is inevitable otherwise that a man should be sometimes too late and sometimes too soon. And these operations are the only ones in which being too soon is a worse fault than being too late. For the general who overstays the proper hour of action only misses his chance, since he can find out that he has done so before he arrives, and so get off safely: but he that anticipates the hour is detected when he comes up; and so not only misses his immediate aim, but runs a risk of ruining himself altogether.
[15.] In all human undertakings opportuneness is the most important thing, but especially in operations of war. Therefore a general must have at his fingers’ ends the season of the summer and winter solstice, the equinoxes, and the periods between them in which the days and nights increase and diminish. For it is by this knowledge alone that he can compute the distance that can be done whether by sea or land. Again, he must necessarily understand The divisions of the day; the subdivisions both of the day and the night, in order to know at what hour to order the reveillé, or the march out; for the end cannot be attained unless the beginning be rightly taken. As for the periods of the day, they may be observed by the shadows or by the sun’s course, and the quarter of the heaven in which it has arrived, but it is difficult to do the same for the night, unless a man is familiar with the phenomenon of the twelve signs of the Zodiac, of the night. and their law and order: and this is easy to those who have studied astronomy. For since, though the nights are unequal in length, at least six of the signs of the Zodiac are nevertheless above the horizon every night, it is plain that in the same portions of every night equal portions of the twelve signs of the Zodiac rise. Now as it is known what portion of the sphere is occupied by the sun during the day, it is evident that when he has set the arc subtended by the diameter of his arc must rise. Therefore the length of the night is exactly commensurate with the portion of the Zodiac which appears above the horizon after sunset. And, given that we know the number and size of the signs of the Zodiac, the corresponding divisions of the night are also known. If however the nights be cloudy, the moon must be watched, since owing to its size its light as a general rule is always visible, at whatsoever point in the heaven it may be. The hour may be guessed sometimes by observing the time and place of its rising, or again of its setting, if you only have sufficient acquaintance with this phenomenon to be familiar with the daily variation of its rising. And the law which it too follows admits of being easily observed; for its revolution is limited by the period of one month, which serves as a model to which all subsequent revolutions conform.
[16.] And here one may mention with admiration that Homer represents Ulysses, that truest type of a leader of men, The example of Ulysses. See Odyss. 5, 270 sq. taking observations of the stars, not only to direct his voyages, but his operations on land also. For such accidents as baffle expectation, and are incapable of being accurately reckoned upon, are quite sufficient to bring us to great and frequent distress, for instance, downpours of rain and rise of torrents, excessive frosts and snows, misty and cloudy weather, and other things like these;—but if we also neglect to provide for those which can be foreseen, is it not likely that we shall have ourselves to thank for frequent failures? None of these means then must be neglected, if we wish to avoid those errors into which many others are said to have fallen, as well as the particular generals whom I am about to mention by way of examples.
[17.] When Aratus, the Strategus of the Achaean league, attempted to take Cynaetha by treachery, Aratus fails at Cynaetha. he arranged a day with those in the town who were co-operating with him, on which he was to arrive on the banks of the river which flows past Cynaetha, and to remain there quietly with his forces: while the party inside the town about midday, when they got an opportunity, were to send out one of their men quietly, wrapped in a cloak, and order him to take his stand upon a tomb agreed upon in front of the city; the rest were to attack the officers who were accustomed to guard the gate while taking their siesta. This being done, the Achaeans were to rise from their ambush and to make all haste to occupy the gate. These arrangements made, and the time having come, Aratus arrived; and having concealed himself down by the river, waited there for the signal. But about an hour before noon, a man, whose profession it was to keep a fine kind of sheep near the town, wishing to ask some business question of the shepherd, came out of the gate with his cloak on, and standing upon the same tomb looked round to find the shepherd. Whereupon Aratus, thinking that the signal had been given, hurried with all his men as fast as he could towards the gate. But the gate being hurriedly closed by the guard, owing to no preparations having yet been made by the party in the town, the result was that Aratus not only failed in his attempt but was the cause of the worst misfortunes to his partisans. For being thus detected they were dragged forward and put to death. What is one to say was the cause of this catastrophe? Surely that the general arranged only for a single signal, and being then quite young had no experience of the accuracy secured by double signals and counter-signals. On so small a point in war does the success or failure of an operation turn.