4.8
Still, you must never neglect to post guards through reliance on spies; on the contrary, your precautions must at all times be as complete as when you have information that the enemy is approaching. For even if the spies are entirely reliable, it is difficult to report at the critical moment, since many things happen in war to hinder them.
4.9
The advance of cavalry is less likely to be detected by the enemy if orders are not given by a herald or in writing beforehand, but passed along. Accordingly, for this purpose, too, that the order to advance may be given by word of mouth, it is well to post fileleaders, and half file-leadersThese form the sixth rank. behind them, so that each may pass the word to as few men as possible. Thus, too, the half file-leaders will wheel and extend the line without confusion, whenever there is occasion to do so.
4.10
When it is necessary to keep a look out, I am all in favour of the plan of having hidden outposts and guards. For these serve at once as guards to protect your friends and snares to trap the enemy.
4.11
And the men, being unseen, are more secure themselves and at the same time more formidable to the enemy. For the enemy, conscious that there are outposts somewhere, but ignorant of their whereabouts and their strength, feels nervous and is forced to suspect every possible position; whereas visible outposts show them where danger lies and where all is safe.
