greatest opportunity.

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 widt