Bomb-traps, extensions of the gallery about 3 feet long, should be dug beyond the point where the entrance to the dugout chamber leads off from the gallery.  These will catch bombs thrown in from the surface and protect the chamber from the effects of their explosion.

Interior.  The standard section is 6 feet by 8 feet, to allow for bunks on each side.  Frames of 6 by 6 timber spaced 2 feet 6 inches apart support the sides and roof.  Roof planking should be 2 inches thick, and the sides should be covered with 1-1/2 inch plank or corrugated iron.  Two shovels and two picks for emergencies should always be kept in each dugout.  The construction of the chamber should be that of a very strong box, so that it will stand strain, if necessary, from within as well as from without.

Depots for Supplies must be near the headquarters of the platoon, company, battalion and regiment.  Shelters may be made with ammunition boxes set into the side of the trench.  Places should be provided for the following:  Food, ammunition for rifles and auto-rifles, grenades, rockets, tools and other supplies.  Places must also be arranged in the front line for ammunition, rockets and hand and rifle grenades.

Telephones.  Communication is established as speedily as possible with the various units.  In the forward trenches wires do not last long under bombardment and fire left open along the side of the trench, where quick repairs can be made.  All soldiers must be taught to respect these wires and to care for them when they are found under foot or hanging.  Conduits are dug for wires to battalion and regimental headquarters, and these are fairly safe from shell fire.

Departure Parallel.  In preparing for an advance upon the enemy, a straight line trench without traverses, and with steps at the end for exit to the surface, is built in front of the first line trench.  This line of departure is generally brought within about 200 yards of the hostile line by means of saps, short trenches run out from the front line to the new parallel.  Since this line of departure can be seen by the enemy, it is sometimes better to construct steps in the front line trench itself, or when possible to build a Russian sap.  This is a tunnel very near the ground, which can be broken through at a moment’s notice when troops are ready to advance.

Machine Gun Emplacements.—­Shell-holes with a good field of fire and emplacements along boyaux are the best location for machine guns.  Few guns are placed in the front line, and these only at strong points in the line, which command a maximum field of effectiveness.  Shell-holes may be imitated for machine gun emplacements, but in any case they should be connected by underground passage with the trenches.  Thus when trenches are destroyed by bombardment the machine guns remain intact.  The field of fire for each machine gun should be carefully determined and marked by three stakes, one for the position of the gun, the other two for the limits of the field of fire.  Using these as guides, the gun can be fired correctly at night.  During the day it is never left in place nor fired from its actual emplacement.