Therefore in such enterprises commanders must be careful about every detail.
The first and foremost requisite is to keep silence, and never either from joy if some unexpected hope shall present itself, or from fear, or from familiarity with or affection for certain persons, to reveal one's design to anyone unconcerned in it,
but to communicate it only to those without whom it cannot be put in execution, and even to these not earlier than when the need of their services renders it imperative.
And we must keep not only our tongues tied but even more so our minds.
For many who have kept their own counsel have revealed their projects either by the expression of their faces or by their actions.
The second requisite is to be well versed in the question of night and day movements and voyages, knowing exactly how far they will bring us, not only by land but also by sea.
The third and most important is to have a notion of time and season and to be able to hit on the right ones for our design.
Nor is the place fixed for the intended coup de main a matter of small importance; for often this shows seemingly possible ones to be impossible.
Finally, we must pay due attention to signals and counter signals, and to the choice of those by whose agency and in whose company our project is to be executed.
Walbank Commentary