300 yards behind the firing trenches. The C. T. in this section
is constructed on the same lines, or may be constructed on the
same lines, as Sections I and II, into whatever proportions local
conditions and practical considerations, and particularly dangerous
places, may dictate. The zigzag plan shown in the sketch is generally
safe to adopt, as it allows rapid transit with a certain amount of
concession to the claims of protection, more so as it approaches the
fire trenches. These C. T.’s generally should be a series of straight
stretches, zigzagging at acute or obtuse angles, the length and angles
governed by local conditions, the extent and direction from which each
stretch might be enfiladed, and the gradient and distance from danger.
It has been shown before that the shorter the stretches and the more
acute the angle at the turn, the less is the danger from enfilade fire,
but the C. T. with this advantage requires a greater length of time
and labor in digging, as well as taking a great deal more time and
effort to pass through it. In order to lessen these things as much as
possible, it is always considered best to adopt longer stretches and
more obtuse angles as soon as possible.
The excavated soil is naturally thrown up on the side facing the enemy,
and thus forming a parapet. It can at times be used as an actual fire
trench. The parapet should fulfill the same conditions as the parapet
of a fire trench, and where necessary, overhead traverses should be
placed. The more of these overhead traverses used, the longer can the
straight run of trench be. When running up-hill, facing the enemy, it
is clearly obvious that acute turns and short stretches are necessary,
or, if it is not found advisable to use these and more time can be
gained by digging the straight runs, then they should be dug deeper and
a great deal of care taken in placing the overhead traverses.
Generally, the farther the C. T. from the enemy, the less necessity
to take measures for stopping hostile advance down it, but it is a
safe thing when time permits to loophole the traverses facing the
long straight stretches either in an ordinary traverse or when time
permits the building of island-traverses, especially at junctions. Such
loopholes command the straight stretch in front and are reached by
narrow trenches very similar to a drainage trench, as indicated at
“H.” Here again, as well, the loopholes for at least one or two should
be for kneeling fire.
Hostile attacks may also be hampered here by using the rolls of looped
wire previously mentioned, or by frames of barbed wire placed at the
side of the trench just behind the parapet, so that a man retiring down
the trench can easily pull them down into the trench after him. Great
care must be taken that C. T.’s running from firing line to support
trenches do not obstruct the fire from the supporting trenches.
[Illustration: SECTION IV
SKETCH OF TRENCH SYSTEM]