2. Sentries—By Night—(a) Sentries will be posted every 2 hours, except under bad weather conditions, when the length of the tour of sentry may be reduced.
(b) From evening "stand to" till morning "stand to" one sentry to every three or four bays in the fire trench will be posted. If wiring or digging parties are out in front, or listening posts are numerous, this number may be reduced.
(c) The next relief will remain within reach of the sentry.
(d) Every sentry is to be regularly posted by a N.C.O., who will explain to him his duties and the front to be watched, and ascertain that the sentry and his relief are aware of the position of the section and platoon commanders, the sentries on either side, and whether there are any patrols or working parties out in front. Should there be salients in the line, the sentry will be carefully instructed, so as to avoid any possibility of him firing toward his own trenches.
(e) By night or in places which have the reputation of being dangerous, i.e., where enemy are suspected of mining, advanced posts, etc., no man should ever be posted alone. There should be either a double sentry post, or the next relief should rest within kicking distance of the sentry.
By Day—(f) The number of sentries required depends on the proximity of the enemy's trench line and whether a good view to the front can be obtained, normally one to every four bays is sufficient.
(g) Every sentry will be provided with a periscope.
(h) Well protected "look out" posts for sentries will be built along the front trench line.
(i) Sending Out of Patrols—Patrols will never be sent out without definite orders as to what is required of them. Patrols will go via a listening post (if such exist). All listening posts will be warned of the strength of the patrol and the approximate hour of departure and return. Word will be passed quietly along the line of sentries that a patrol is out in front.