nches.= Dummy trenches frequently cause the hostile
artillery to waste time and ammunition and to divert its fire. (492)

=507. Location, extent, garrison, etc., of fieldworks.= The location,
extent, profile, garrison, etc., of fieldworks are matters to be
decided by the infantry commanders. Officers must be able to choose
ground and properly intrench it. (See "Field Fortifications," Chapter
XVI, Part III.) (493)

=508. Outlining trace of trenches in combat exercises.= In combat
exercises, when it is impracticable to construct the trenches
appropriate to the exercise, their trace may be outlined by bayonets,
sticks, or other markers, and the responsible officers required to
indicate the profile selected, method and time of construction,
garrisons, etc. (494)

DEPLOYMENT FOR DEFENSE

=509. Density of whole deployment.= The density of the whole
deployment depends upon the expected severity of the action, the
character of the enemy, the condition of the flanks, the field of
fire, the terrain, and the available artificial or natural protection
for the troops. (495)

=510. Density of firing line.= If exposed, the firing line should be
as dense in defense as in attack. If the firing line is well
intrenched and has a good field of fire, it may be made thinner.

Weaker supports are permissible. For the same number of troops the
front occupied on the defensive may therefore be longer than on the
offensive, the battalions placing more companies in the firing line.
(496)

=511. Strength in rear to be increased when change from defensive to
offensive is contemplated.= If it is intended only to delay the enemy,
a fairly strong deployment is sufficient, but if decisive results are
desired, a change to the offensive must be contemplated and the
corresponding strength in rear provided. This strength is in the
reserve, which should be as large as the demands of the firing line
and supports permit. Even in a passive defense the reserve should be
as strong as in the attack; unless the flanks are protected by other
means. (497)

=512. Post of supports; cover for supports.= Supports are posted as
close to the firing line as practicable and reinforce the latter
according to the principles explained in the attack. When natural
cover is not sufficient for the purpose, communicating and cover
trenches are constructed. If time does not permit their construction,
it is better to begin the action with a very dense firing line and no