approach within a few hundred
yards of the trench and robbed them of the concealment they had hoped
to gain. The choice between a site in front, and one in rear of a
crest, is influenced by local conditions which govern the
effectiveness of our own and the enemy's fire. In general, the best
location for effective fire trenches, lies between the military crest
of rising ground and the lowest line from which the foreground is
visible. If the position on the military crest is conspicuous, it is
inadvisable.

With regard to the nature of the ground, trenches should, if
practicable, be so located as to avoid stony ground, because of the
difficult work entailed and of the danger of flying fragments, should
the parapet be struck by an artillery projectile.

To locate the trace of the trenches, lie on the ground at intervals
and select the best field of fire consistent with the requirements of
the situation.

Trenches should be laid out in company lengths, if possible, and
adjoining trenches should afford each other mutual support. The flanks
and important gaps in the line should be protected by fire trenches
echeloned in rear.

=1162. Concealment of trenches.= Owing to the facilities for
observation that the aeroplanes and other air craft afford, and to the
accuracy and effect of modern artillery fire, every possible means
should be taken to conceal trenches, gun implacements, and other
works. The aim should be to alter the natural surface of the ground as
little as possible and to present a target of the smallest possible
dimensions. Covering the parapet with brush or grass will afford
temporary concealment. If the new earth can be sodded it aids greatly
in concealing the trench. In some cases troops have gone to the extent
of painting canvas to resemble the ground and have placed it over
trenches, guns, etc. Straw and grass placed in the bottom of trenches
make them less conspicuous to air scouts. When trenches are dug on a
fairly steep slope care must be used to conceal the back of the
trench, which, being higher than the parapet, will stand out as a scar
on the hillside. Grass or brush may be used to conceal the back of the
trench.

=1163. Dummy trenches.= May be constructed which attract the enemy's
attention and draw his fire, or at least a part of it. The extent to
which this method may be used may include the construction of dummy
obstacles and guns, and even hats may be placed on the parapets.

=1164. Length