1. Watches at night must be strictly kept in time of war and when the enemy are close to the city or camp. 2. The commander-in-chief and his bodyguard should be stationed round the town hall and market place, if this position is a defensible one, otherwise, he should have previously occupied the strongest place in the city, and the most conspicuous from all quarters. 3. The bugler and the dispatch-runners should always be quartered next to the generalís lodging, ready at hand in case bugle-calls or messages are needed, so as to give the guards and the rounds notice of what is to be done, wherever they happen to be in their circuit of the city. 4. Secondly, the guards on the wall, in the market place and at the town hall, the entrances to the market place, the theatre, and other points occupied should have short periods on duty: the reliefs should be frequent and their numbers strong. 5. For in a short period on guard a man will not have time to effect communication with the enemy and complete any treasonable design before he is relieved, and men will be less likely to fall asleep at their posts if they are on duty for a short time only; and with large numbers it is more likely that information will leak out concerning any attempt at treachery. 5a. Thus it is desirable that as many men as possible should be on the alert at time of danger, and that everyone should go on guard duty during the night, so that there may be as many men as possible in each relief; 6. with small numbers and infrequent reliefs men are likely to fall asleep owing to the length of their watch, and intending traitors will have ample time to communicate with the enemy unobserved before they are relieved. These considerations, therefore, have to be borne in mind.
7. At a critical time these further precautions should be added. None of the sentinels should know beforehand in which relief or at what point in the city he will be on guard; nor should the same commanders be always in charge of the same detachment; in all matters concerned with the supervision of citizens changes should be made as frequently as possible. A traitor will have far less chance of betraying anything to outsiders or receiving information from the enemy, 8. when no-one knows beforehand at what point of the wall he will be at night, or who his companions will be, but everyone is in complete ignorance of his destination. Those who have kept guard by day should not do so at night as well: for it is inadvisable that men should know in advance on what duties they will be deployed.
9. Patrols from the sentries on the wall may be sent out in the following manner. In every watch one man from every guard station is to patrol as far as the next station; from there another on to the next, and so on; the order for all these patrols to start should be given by one signal. 10. Thus there will be several men on their rounds at once, and each will only have a short way to go; neither will the same men remain together, but new guards and new patrols will be constantly meeting each other. This system will prevent treachery on the part of the guards. 11. The patrols, when not actually on their round, should stand facing each other: in this position they will be able to survey the country in all directions, and are least likely to be surprised by anyone coming stealthily upon them, a misfortune which, as we saw, has happened before in the case of day outposts. 12. During stormy or dark nights they should throw down one stone after another onto the ground outside the walls, and challenge as if they saw someone coming: for in this way anyone approaching will inevitably be discovered. 13. If it is thought advisable, the same may be done on the city side as well. Some, however, say that this is a bad plan: for the enemy approaching in the dark are warned by the voices of the men on their rounds and the throwing of stones not to attack at that particular point, but rather at a place where no sound is to be heard. 14. The best plan on such nights is to keep watchdogs chained up outside the wall: these will be quicker to detect the enemyís spies, deserters stealing up to the city, or anyone making his way out at any point with intent to desert; their barking, too, will wake the sentinel if he happens to be asleep.
15. The quarters of the city which are most accessible to attack should be guarded by the wealthiest and most distinguished citizens, whose interests are most closely bound up with those of the city: for they more than anyone else will have reasons for seeing that they do not turn aside to self-indulgence, but always attend diligently to their duty. 16. During public festivals those of the troops on guard in the city who are untrustworthy and most suspected by their own comrades must be dismissed from their posts with leave to keep the feast at their own houses: 17. this will seem to them as a special mark of distinction, and at the same time give them no chance of causing mischief. Others more loyally disposed should be placed on guard in their place; for it is at festivals especially that revolutionary designs are put into execution. 18. The disasters that have happened on such occasions are described elsewhere [in chapter 17]. 19. At these times, therefore, it is also better for the ways up onto the wall to be rendered difficult of access and kept closed, so as to give an intending traitor no opportunity of seizing any part of the wall, which will be manned by guards of your own choosing who have no alternative but to stay at their posts; while if the party succeeds in climbing up from the outside unobserved, they will not be able to come down off the walls into the city without some trouble and delay, unless they are willing to take the risk of jumping down from a height in full view of an enemy awaiting them. This plan of blocking the ways to the wall will be useful also in a tyrantís citadel. 20. After the battle of Naxos, Nicocles, the commander of the garrison, against whom a plot was being formed, had the ascents blocked up, posted guards on the walls, and kept up a patrol with dogs outside the city; for a treacherous attack was expected from without.
21. When there is no disaffection or suspicion within the city, lights should be kept burning in lamps by night at the posts on the walls, so that a signal can be given to the general by raising the lamps when a hostile move is directed against any point. 22. If the nature of the ground prevents the general from seeing a lamp on the wall, a transmitting station must forward the signal with another lamp, whereupon the general should communicate the news to the other posts, either by bugle-call or orderly, as is most convenient. 23. At such critical times, when the sentries are kept strictly at their posts in this way, orders should be issued to the rest of the populace that after the signal none are to leave their houses: if anyone finds it necessary to do so he must take a lamp, so as to be seen clearly at a distance by the men on their rounds. 24. No craftsmen must work at night, lest the noise should disturb the guards.
The fair and equal distribution of the watches among the troops, varying with the length of the nights, must be regulated by a water-clock. This should be made to the change of the reliefs. 25. It is better for its inside to have a coating of wax: as the nights grow longer some of the wax should be removed, to allow room for more water; as they grow shorter, more wax should be inserted, so that the clock holds less. Enough then of the question of the fair distribution of watches.
26. When danger is less imminent, half of the numbers indicated above will be sufficient for the guards and rounds, and so half of the army will be on guard each night. In time of peace, when there is no danger, as few men as possible should be troubled with sentry duty, and to the least possible extent.
27. If the general has to send out rounds, a stick with a seal upon it should be delivered from the general to the first sentinel, passed by him to the next, and so on until the stick has completed the circuit and is returned to the general. Orders should be given to each patrol not to carry the stick further than to the next sentry; 28. and if on arrival he finds the post vacant, to return the stick to the man from whom he received it, so that the general may be notified, and identify the offender who is absent from his post. 29. If a man is not present to mount guard at the place appointed, his company commander must at once sell his post for whatever premium it will fetch and appoint a man to keep watch instead of him. Then the citizen who engaged him must supply money to pay the man who bought the post, and next day he regimental officer must inflict the usual fine on the defaulter.