In this connection it must be remembered that:— (_a_) If the sandbags are left in place for a considerable time without being removed, they may become embedded and be found unmovable. (_b_) That loopholes filled with single sacks will not be bullet-proof. Training the gunners to:— (_a_) Remove the gun quickly from the tripod and fire from the top of parapet without it. (_b_) Lift the gun and tripod out of the trench and fire it from some previously selected spot. NOTE.—Both these methods require much practice. Every endeavour should be made to conceal the position of the gun from the front. Gun emplacements must therefore be made to appear exactly like the remainder of the trench or breastwork. Several emplacements should be made for each gun, and practice should be made in moving guns quickly from one emplacement to another. =Guns may be placed=—IN THE FRONT LINE OF TRENCHES.—This may be taken as the general rule. IN SUPPORT TRENCHES.—There are occasions when it may be advisable to place guns in the support trenches. Here they may be arranged so as to:— Prevent a further advance of the enemy should they capture the front line. Enfilade the front line should it be captured. Sweep the communication trenches. IN POSITIONS IN REAR.—If the ground is favourable it may be possible to place guns, in concealed positions, in rear of the entrenched line. They can be arranged so as to:— Fire over the trenches and sweep the ground in front. Fire through gaps in the defensive line. Command positions where the enemy may concentrate prior to the assault. Command positions likely to be occupied by the enemy’s machine guns. Command covered approaches on the defensive line. Enable guns to fire on enemy’s trenches with greater effect. Give overhead covering fire in case of an advance by our own troops. General Notes on Trench Work. If guns are often used, the positions from which they are fired should frequently be changed. Thus the enemy may be deceived as to the number and position of the guns. Emplacements should be numbered, and range cards placed in each. When taking over a line of trenches the machine gun officer must make careful arrangements for controlling the fire of his guns. The machine gun officer must:— (_a_) Establish himself at a place where he can always be found. (_b_) Keep in touch with his guns with the officers of the line of trenches he is assisting to defend. (_c_) Arrange for ammunition supply. (_d_) Arrange for reliefs. =Towers, windmills and other high buildings= may often be used with advantage:— For overhead fire. (_a_) Cover the advance of friendly troops. (_b_) Fire at attacking enemy over the heads of our own troops. (_c_) Enable fire to be directed into enemy’s trenches.