Book 9
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Now the head and front of such precautions is silence; andThings necessary. 1. Silence. not to allow either joy at the appearance of an unexpected hope, or fear, or familiarity, or natural affection, to induce a man to communicate his plans to any one unconcerned, but to impart it to those and those alone without whom it is impossible to complete his plan; and not even to them a moment sooner than necessary, but only when the exigencies of the particular service make it inevitable. It is necessary, moreover, not only to be silent with the tongue, but much more so in the mind. For it has happened to many generals before now, while preserving an inviolable silence, to betray their thoughts either by the expression of their countenances or by their actions.
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The second requisite is to know accurately the conditions2. Knowledge of the capabilities of the force in moving. under which marches by day or night may be performed, and the distances to which they can extend; and not only marches on land, but also voyages by sea.
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The third and most important is to have some knowledge of the seasons, and to be able to adapt the design to them.
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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.
