Lookout and Listening Posts
Except when the garrison are actually required to man the parapet, they will be kept under cover, with the exception of a few lookouts, whose duty it is to give timely warning of the movements of the enemy.
When the opposing forces are in close proximity to each other mining operations are generally resorted to by both sides to compass the destruction of the opposing works and open the way for an attack.
Lookout and listening posts serve the double purpose of having a few men at the most advantageous places for observation at the front and flanks and providing points at some distance to the front of the first line fire trenches from which listeners may be able to discover the location and direction of enemy mining operations before they really menace the fire trench.
In the normal case there will be some natural cover available. Such, however, is not always the case, and specially constructed observation stations have to be provided.
The posts should be placed in advance of the first line trench, the distance depending upon circumstances which have to be determined in each particular instance. They must be fully protected from reverse fire so that there will be no chance of the observer masking the fire of his comrades manning the fire trench.
Unless the ground is very favorable it will be found difficult to provide for observation above ground. Where there are natural features such as embankments, mounds, hedgerows, ruins of buildings, etc., it may be possible to make provision for observation even by day.
Where a loophole is used, the type having the narrower end outward should be provided.
In the open type of post the observation directly to the front may be greatly facilitated by the use of the periscope. (Plate 11.)
A good, strong parapet thrown up and chopped off at the corners will enable the observer to cover areas from an oblique direction from the post and protect him from fire from the front.