Trench Construction.—­The methods of building trenches are the same whether the work is carried on under fire or not.  In an attack, upon reaching the limit of advance, the men immediately dig themselves in, and later connect these individual holes to make a continuous line of trench.

Most of the digging must be done at night, and must be organized to obtain the most work with the least confusion.  There are three ways of increasing the efficiency of the men.  In the first of these, squad shifts, the squad leader divides his men into reliefs and gives each man a limited period of intensive work.  Reliefs may be made by squads or by individuals.  The second way of increasing efficiency is to induce competition among the man and squads, thus making the work a game in which each soldier’s interest will be aroused in the effort to do better than the others.  The third method is to assign a fixed amount of work to each man.  An average task, which all ought to accomplish in a given time, is found by experience, and those who finish before their time is up are relieved from further work during that shift, and allowed to return to their shelters.

Continual care must be used to check up the tools on hand, as the men are prone to leave them where they were working rather than carry them back and forth to work.  Each unit must guard its property from appropriation by neighbors on its flanks.

System of Laying Out Trenches.—­The trace of the trench is first staked out, particularly at traverses and corners when the work is to be done at night.  Measurements should be exact, and the men should be required to line the limits of each trench so as not to exceed them in digging.  All sod should be taken up carefully and used on the parapet for concealment or on the berm to make a square back wall for the dirt of the parapet.  If possible this should be done with the parados wall, so as to make it as inconspicuous as possible from the front.

Men should begin to dig at the center of the trench and throw the dirt as far out on the sides as possible, so that as they go deeper the earth can be thrown just over the berm.  The slope of the sides will be kept steep and the men prevented from widening the trench as they dig.  In sandy soil the sides of the trench should be allowed to reach their angle of repose (which is wider at the top than required), then the trench walls supported with revettments to the proper width, which are filled in behind with sand.  Always dig to full depth before beginning to revet, as it is impossible to dig deeper afterwards without loosening the revetting.