(ii) In defence, the arrangements for fire action will include the various measures described in Chapter VIII of _Field Entrenchments_ of this series, such as clearing the foreground of features which would afford cover to the enemy and assist his advance, and clearing it of features to improve the defenders field of fire, together with the construction of different obstacles to impede and check the enemy’s advance or cause him to select lines of approach along avenues commanded by the fire of the defenders. =6. Direction and Control of Fire.=--Fire is said to be _directed_ by the commander, who defines the objective against which it is to be used, and to be _controlled_ by the fire-unit commanders, who give the necessary executive words of command. In attack occasions will frequently arise when fire-unit commanders must both direct and control the fire of their units, while at close ranges, or when men are widely extended, it may happen that the transmission of any fire-order is impossible, and that each individual man must control his own fire. =7. Fire-Unit.=--The normal infantry fire-unit is the section, though under certain conditions at the longer ranges the fire of a platoon, or even a whole company, may be controlled by its commander. _The efficiency of section commanders is therefore of paramount importance._ [Illustration: Emery Walker Ltd. sc. =Fig. 47.=--ROUGH SKETCH OF A FIELD OF FIRE DIVIDED INTO OVERLAPPING SECTORS BY THE USE OF DESCRIPTION POINTS ON DEPLOYMENT IN ATTACK.] =8. Duties of Fire-Unit Commander.=[20]--(i) The value of a fire-unit commander depends upon his ability _to apply the fire of his unit at the right time and in the right volume to the right target_. In addition to his other duties, the fire-unit commander is responsible for: (_a_) Indicating targets. (_b_) Issuing orders for sighting, and, when possible, supervising the correct adjustment of sights. (_c_) Regulating the volume of fire, whether deliberate or rapid. (_d_) Reporting to platoon or company officers when ammunition is running short. (ii) The additional duties of the fire-unit commander referred to in the above paragraphs may be described generally as follows: (_a_) Watching for favourable targets. (_b_) Watching for signals from platoon or company officers. (_c_) Observing effect of fire. (_d_) Seizing all chances of firing for mutual support. (_e_) Seeing that all orders are properly passed. (_f_) Seeing to issue and redistribution of ammunition. (_g_) Selecting halting places in attack. (_h_) Making best use of ground and cover. (_i_) Re-forming and telling off units as opportunity offers. During the attack advantage will be taken of dead ground and cover to re-form separate units which may become mixed owing to confusion, especially in the later stages of attack.