5. In the instruction of the brigade or division a most useful exercise is to practice deployments for attack under different suppositions, such as an enemy occupying different extents of front, an enemy suddenly discovered in position half-right, half-left, or flanking the line of march.
THE DEFENCE.
160. Distribution of Infantry for defence.
1. Infantry detailed for the defence of the entrenchments will generally be distributed in two bodies, viz.,
(i) Firing Line and Supports.
(ii) Local Reserves.
For the decisive counter-attack, a separate body, The General Reserve, which has nothing to do with the immediate defence of the entrenchments, will be retained in the hands of the officer commanding.
2. The strength of the firing line will depend entirely on the extent of the field of fire and the character of the cover. If the conditions are favourable to the defence a few men can easily protect a wide front. If there is any chance of a surprise, or of the position being attacked by a sudden rush, the firing line should be as dense as is compatible with the free use of the rifle by every man engaged.
3. The duty of the supports is to replace casualties in the firing line, and they should therefore be posted near at hand and under cover. In strong positions very small supports will be quite sufficient, or they may even be dispensed with altogether.
4. The duties of the local reserves are to deliver local counter-attacks, to reinforce the firing line at critical moments, and to protect the flanks; they will also furnish the outposts and supply detachments to occupy temporary positions, either in front or beyond the flanks of the entrenchments. S. 161 (7), also “Combined Training,” 125 (4). Local reserves should be well covered, especially from artillery fire; but there should be no obstacle to their being brought rapidly to the front.