iv. To destroy defended localities such as villages, farms,

or the strongly entrenched portions of a position. v. To support an attack up to the moment of assault.

2. Their wide field of fire enables howitzers to cover a zone of considerable extent, and they are particularly adapted to the support of infantry in the later stages of an attack, owing to the steep angle of descent of their projectiles. (_See_ Sec. =157=.)

Troops in movement or other targets presenting only a fleeting opportunity do not come within the normal rôle of howitzers, which, however, should be prepared to engage such objectives, if circumstances make such action advisable.

3. The chief conditions for effective howitzer fire are good gun platforms, and facilities for both observation of fire and the exercise of command. A position behind natural cover is obviously preferable, provided these conditions are fulfilled.

=143.= _Heavy artillery._

1. The special characteristics of heavy artillery are accurate long-range fire and great shell power, but these advantages are to a certain extent discounted by a limited mobility. The long-range fire of guns of this nature should be utilized to bring enfilade and cross fire to bear on the enemy’s positions. The sites chosen for them should be such as to facilitate fire being brought to bear on as much of the ground occupied by the enemy as possible. In normal circumstances these conditions are most likely to be obtained by dispersion.

The fire of guns of this nature is of special value against shielded guns, fortified localities and buildings.

2. Owing to the limited mobility of these guns and the fact that they are unprovided with shields, considerable risk may be incurred without adequate compensation, if they are placed too far forward, or exposed on a flank.

Occasions may, however, occur, when to gain decisive results, it will be necessary to use them in line with those of lighter calibre.

3. If well protected and placed on the flanks of a defensive position in an open country, their long-range fire may compel a turning movement to be made on so wide an arc, that time, valuable to the defenders, may be gained.

=144.= _Mountain artillery._

1. In country where wheeled traffic is impracticable, light guns carried on pack animals are the only substitute for field artillery, but the use of mountain artillery is not restricted to such country. Infantry requires effective support throughout the attack, and as pack animals can go practically anywhere that an infantry soldier can go without using his hands, batteries of mountain artillery are peculiarly suited to work with infantry in difficult country of any kind.

2. Hills, woods, and broken or enclosed country, which might be impassable to wheeled artillery, present little difficulty to pack animals, and, as cover, which will conceal a man standing upright is sufficient for them also, batteries of mountain artillery will often be able to work their way forward on a battlefield without attracting attention, where the movement of wheeled artillery could not escape detection.

Moreover, the utility of mountain artillery is not confined to supporting the infantry in the various forms an attack may assume, for in the defence of woods, in temporary forward positions occupied by the defence, and in rearguard action, its mobility and easy concealment will often enable it to render valuable service.

In short, mountain batteries are capable of being of great value on many occasions when circumstances are unfavourable to the use of wheeled artillery, with which, however, they compare unfavourably in respect of shell power.

PRINCIPLES OR EMPLOYMENT.

=145.= _Objects of fire._

=1. Artillery cannot ensure decisive success in battle by its own destructive action.= It is the advance of the infantry that alone is capable of producing this result.

=To help the infantry to maintain its mobility and offensive power by all the means at its disposal should be the underlying principle of all artillery tactics.=

The primary objects of artillery fire should therefore be:--

i. To assist the movements of its own infantry. ii. To prevent the movements of the enemy’s infantry.

These objects may be attained by--

(_a_) Inflicting losses on the enemy, and breaking down his fighting spirit. (_b_) Destroying his _matériel_. (_c_) Reducing the resisting power of fortified localities and rendering them more easy of approach.

It is legitimate, therefore, to use artillery fire for any of these purposes, in so far as they contribute towards the end in view.

=146.= _Concealment._

1. The provision of suitable equipment enables batteries to deliver effective fire from positions in which they are completely concealed from the enemy. The batteries may thus be able to retain their mobility, and remain at the disposal of the commander of the force in the event of a change in the situation.

2. =Concealment in action increases the difficulties of the hostile batteries, possibly even to the extent of conferring immunity from their fire, thus enabling the concealed artillery to devote its attention to the support and assistance of its own infantry.=

Although the employment of aircraft for reconnaissance has modified the possibilities of complete concealment to some extent, guns in action may escape observation from the air if they are carefully sited.

Groups of horses and wagons in the open are very easily seen from aircraft and even when the guns are not visible may be an indication of the presence of artillery. Advantage should therefore be taken of woods, avenues of trees, or other features whenever possible to conceal the limbers, first line wagons and horses of artillery.

The power of delivering effective fire from concealed positions is, however, limited. Rapid movement or very fleeting opportunities are difficult to deal with. Distant observing stations involving the passage of orders by mechanical means increase the difficulty. The amount of dead ground which can be left in front of the guns may also be a matter of serious concern.[10]

[10] Supposing that guns and target are on the same level, then to guns 60 yards in rear of a crest and 16 feet below it all ground is dead within 3,000 yards; if 9 feet below it all ground is dead within 2,000 yards; if 3 feet below it all ground is dead within 1,000 yards.

On the other hand batteries exposed to view will usually be compelled to enter into an artillery engagement for their own protection, in which they will start at a disadvantage. This is less likely to occur at the crisis of the fight when the struggle of the infantry at close quarters may monopolize the attention of the combatants.

=3. Concealed manœuvre favours surprise=, and should therefore be sought for up to the moment of opening fire, due regard being had to tactical requirements. Even if the enemy is at once able to locate the flashes the more vulnerable portions of the battery will probably have been safely disposed and some measure of surprise attained. The advantages to be gained from moving batteries into position under cover of darkness have increased owing to the difficulty of evading observation by hostile aircraft.

=4. Concealment, both as regards position and manœuvre, must invariably be foregone for adequate reasons. To support infantry and to enable it to effect its purpose the artillery must willingly sacrifice itself.=

To move in column of route on a road in circumstances where a lucky shot will bring the column to a standstill is to court disaster. On the other hand, when deployed, rapid movement over open ground exposed to fire for a short distance is accompanied by but slight risk; or, when the enemy’s attention is fully occupied elsewhere, movements may become possible which would have no reasonable chance of succeeding if the enemy was on the look out for them.

5. Knowledge of the general tactical situation and discrimination are essential on the part of all who order artillery movements on the battlefield.

=147.= _Economy of force._

1. Artillery, owing to its mobility till subjected to effective fire, its great rapidity of fire and its power to fire effectively while remaining concealed, is able in most situations to conserve its energy, selecting its own time for action and realizing to a great extent the value of surprise effect.

=The principle of economy of force is, therefore, particularly suitable to the tactical employment of the arm, but must always be subordinate to the necessity of employing sufficient force to attain the object in view.=

2. When an encounter with the enemy takes place sufficient artillery should be deployed to support the advanced troops and to cover the deployment of the infantry. The remaining batteries should be assembled in positions of readiness.

As the plan of action develops, tasks will be assigned to the different artillery units, and they will be brought into positions suitable for their purpose. If it is not necessary to open fire immediately they will remain in observation of the zones assigned to them.

3. =Fire will not be opened with more guns than are necessary for the task in hand.= In deciding on the number of guns with which to open fire, the total number available, the frontage that they can conveniently cover with their fire and the extent and tactical importance of the objective must be considered. Efforts must also be made to foresee the course of the action, and to keep a reserve of fire power in hand to meet successive requirements as they arise.

To justify the opening of fire there must be a definite tactical object and a reasonable probability of attaining it. Ineffective fire is not only a waste of ammunition, but affords encouragement to the enemy and gives him information. It should therefore be avoided whenever possible.

4. =Expenditure of ammunition should, as a rule, be proportionate to the tactical importance of the objective and the probability of obtaining results commensurate with the expenditure.= In deciding whether to engage an objective its vulnerability and tactical importance should, therefore, be considered.

When an objective is both vulnerable and tactically important a considerable expenditure of ammunition is obviously justified, but important tactical objectives are frequently invisible or relatively invulnerable. The expenditure of ammunition in such cases must be governed by the urgency of the tactical situation.

5. The objects of keeping artillery in hand are:--