LISTENING POSTS
As before mentioned, in the space between the front lines of the opposing armies, which is known as No Man’s Land, there are sometimes large and sometimes small areas of ground, ditches, streams, etc., which cannot be satisfactorily watched from a fire trench immediately facing them, owing to the lay of the land, hedges, old excavations, buildings, etc. This is the case in a great many instances regardless of the careful thought and the amount of time spent in siting a fire-trench, as the siting of all trenches is largely subsidized by the tactical position of the flank trenches. Very often a line of trenches is taken up under stress of circumstances that do not permit of the obeying of the rules and standards set for an ideal fire-trench.
The control of these areas is essential to prevent small surprise attacks, cutting-out parties and raids. During the day they are very often observable from a flank trench or higher observation ground in the rear, but at night this is not possible; so that listening or observation posts are gradually sited in front of the fire trench with due consideration to the situation in that immediate vicinity. A ruined shed, shack, cart, or any other thing of a similar character lying in No Man’s Land is very useful for these purposes if it can be reached before the enemy reach it with the same purpose in mind. This cannot be used very long, as its purpose is too obvious and peace and quietness will not last long, but it will do until a more satisfactory arrangement can be made.
The listening post is often dug just inside the outer fringe of your own barbed wire entanglements, and is just large enough to allow two men to stand in unobserved. It should be reached by a very narrow, irregular trench running out from a fire-bay, where it is fairly easy to secure the maximum amount of concealment necessary to give protection. The soil excavated from these places must not be thrown out, but placed in sand bags and taken into the trench and used there. It is always best and requires very little more labor, and gives the maximum amount of protection to your listening post if communication to it be made through a tunnel.
These things are bound to be discovered within a certain amount of time, and when you know the position of your listening post has been found by the enemy, which you will know very quickly, owing to the amount of bombs and rifle fire it will receive for one or two nights, until you can dig another one, it is a safe thing to build up a small parapet, taking it down every morning before dawn. It then becomes necessary to dig a new post, and this can be generally done by leading off from your old communication trench to some more favorable spot. When the new post is ready for occupancy, the old one should be filled in with barbed wire, or completely filled in again with dirt, and the sandbag parapet left to mislead as long as possible.
The first duty of a listening post is to listen and report. Most of the work is done at night, and no firing or sniping must be allowed from it during the day. Patrols generally come out via one listening post and return by another, so that all listening posts must be warned of the trench by which the patrol will come out and the approximate hour of departure and return. Patrols should never be sent out without definite orders as to what is required, and especially as to the listening post they leave and return by. Listening posts should fire without challenge at any one who approaches within sight, whether friend or enemy, unless it has been warned that a friendly patrol is out, in which event signals should be pre-arranged. Then the listening post will use the greatest caution and should challenge audibly when the patrol is close, and unless immediately satisfied, fire. Listening posts are connected with the fire trench by a cord or wire, and a simple code of tugs is arranged, or a bell fastened to the fire trench end for alarm in case of emergency, and here a sentry always stands to get any signals that may come from the listening post.
If a listening post has not been warned that a friendly patrol is out and fires on it without challenge, the L. P. is absolved from all blame.
When a hedge or ditch, which might easily provide cover to the enemy, is running parallel with the firing trench, it must be controlled at night by a machine or Lewis gun which is able to enfilade a frontal advance over open ground leading to it. If, as is often the case, the parallel hedge or ditch is easily approached along either hedges or ditches running at right angles to it, these angles must be protected by machine or Lewis gun firing down them.
When hedges or ditches running at right angles from the firing line and leading towards the enemy are in a sector of line, they should be protected from dusk to dawn by one or two men, generally only armed with bombs to protect against surprise, and great care must be taken that no more signs than possible are left to the occupancy of this position over night.