AT NIGHT.
17.—Double sentinels.
Post double sentinels in each section, each man watching in turn, the other resting but within call.
18.—Silence.
They should refrain from making the least noise so as to hear and not be heard.
19.—No firing when fired upon.
There should be no firing when the enemy fires since when the enemy fires, he does not advance.
20.—Look and listen.
They should keep a sharp lookout but listen even more attentively.
21.—In the listening posts.
Sentinels in the listening posts should listen especially for the noise of crushed branches, stirring leaves, slight noise of arms or utensils.
If enemy is detected, these sentinels should hasten back to fire trench to give the alarm quietly so that the enemy may be surprised.
They should fire only if they are themselves caught unawares.
Listening posts should not be too numerous, about two per battalion.
If there are no listening posts, patrols should be sent out to favorable spots especially at sundown and before sunrise.
22.—Enemy sighted or heard, fire.
If the night is clear and the terrain is open, proceed as during the day: If the enemy is sighted or heard, fire in short volleys. In case of doubt throw grenades with the first volley.
23.—Otherwise no firing.
Otherwise, absolute silence should be observed. No firing whatever.
24.—Unless night is dark.
If the night is dark, to avoid surprise, keep up firing: One man per section should fire in turn, from time to time varying the direction.
25.—Digging by enemy.
If digging by the enemy is reported, cease firing. Have it located, throw bombs followed by volleys. Notify sappers for counter mining.
26.—Watch for light of enemy's fire.
If enemy fires, note where light appears.
27.—Posting of sharpshooters.
Locate sharpshooters in advantageous posts behind the trenches (trees, etc.). Have them fire into the enemy's listening posts and into the enemy's trench, especially wherever light appears. These posts should not be occupied during the day.
28.—Patrols.
Send out patrols, stationary or mobile.