If a trench is to be occupied for any length of time, especially if much ground or falling water is to be encountered, drainage becomes of prime importance. Many years ago a celebrated military authority asserted that “nothing so saps the courage of a soldier as to wet the seat of his breeches.” This may be accepted as a true maxim, especially in cold weather. The trench should therefore be made as dry as possible. The floor of the trench should be given a sufficient slope to the rear where an intercepting drain should carry the water to prepared sumps or to a point from which it can be disposed of by drainage. Provision should also be made to exclude surface drainage from the trenches. A scheme for trench drainage is shown in the illustrations (Plates 16, 17 and 18). Overhead cover may be provided as shown in Plates 19 and 20. Loopholes are made wherever head cover is provided. Where the enemy’s trenches are close, there is considerable danger in using them. Collective firing takes place over the parapet. When loopholes are used they should face half-right or half-left and not directly to the front. [Illustration: PLATE 16.—Method of draining trench.] [Illustration: PLATE 17.—Details of trench drainage.] [Illustration: PLATE 18.—Detail of trench drainage.] [Illustration: PLATE 19.—Overhead cover.] [Illustration: PLATE 19a.—Overhead cover.] [Illustration: PLATE 20.—Overhead cover.] [Illustration: PLATE 20a.—Overhead cover.] The disadvantages of loopholes are: 1. The difficulty of concealing firing points. Loopholes give the enemy’s snipers an easy mark. 2. They lessen the number of rifles that can be used at a given point. 3. The necessary head cover makes it difficult to get out of the trench quickly. 4. Damaged head cover often spoils a good firing point. The three types of loopholes are: 1. Narrowest point of the opening nearest the marksman. This type is most difficult to conceal, much of the parapet thickness is cut away and, if of hard material, tends to deflect the bullets into the firer’s face. This defect may be remedied somewhat by stepping the surface of the loophole. 2. Narrowest point to the front. Easiest to conceal but gives a limited field of view. 3. Narrowest point midway between the front and rear. A compromise between the first two types. The following general remarks on the construction of loopholes are taken from a work based upon the experience gained during the war in Europe: 1. The angle of splay is usually 60 degrees. The thicker the parapet the smaller must be the angle of splay. [Illustration: PLATE 21.—Types of loopholes.]