This note is supplementary to that on "Preparatory measures to be taken by Armies and Corps before undertaking offensive operations on a large scale."
I. The general plan of attack
II. The artillery plan
III. The preliminary arrangements
IV. The preparation of the attack
V. The support of the attack
VI. Gas and smoke
Appendix A. Estimate of ammunition required
Appendix B. Example of the employment of a forward gun
Appendix C. Particulars of principal bombardments
Appendix D. Example of a time table
1. Duty of the Artillery Commander.
In all offensive operations it is the duty of the officer commanding the artillery of the force engaged, whether this is an infantry brigade with artillery attached, a division, a corps, or an army, to prepare an "artillery plan" as described in this paper. This plan will be based on, and supplementary to, the general plan of attack.
2. Selection of the front of attack.
Under present conditions, no offensive operation can be expected to achieve complete success unless both the preparation and support by the artillery are effective; and for this it is not enough that the requirements in guns and ammunition should have been correctly estimated and adequately provided. The first and most essential element of success is that the front selected for attack should admit of a full development of artillery fire, and of complete co-operation between the artillery and the infantry. It is only when the ground allows of artillery commanders
It is, then, the first duty of the artillery commander to place before the general officer commanding the force full particulars as to how the ground affects the efficiency of the artillery preparation and support, so that the latter may give due weight to such considerations in selecting the front of attack. "An objective which may appear at first sight easy of access to the infantry, may prove in the end costly to attack, if it does not lend itself to the judicious application of artillery fire; and vice versa, localities which present difficulties to the infantry alone may, if it is possible to bring the converging fire of artillery to bear on them, be carried with comparatively little loss."
3. Estimate of guns and ammunition required.
The general plan of attack having been settled, it is the next duty of the artillery commander to prepare an estimate of the amount of artillery and of ammunition required for the operation. The first point to remember is that the ammunition required depends upon the work to be done, i.e., upon the enemy's defences, more than on the number of guns available. The latter is, however, the governing factor as regards the time which will be required for the preparation, and has therefore an important bearing on the general plan of attack, for if surprise forms any part of the latter, it is essential that sufficient fire units should be available to allow of the different portions of the enemy's defences being bombarded simultaneously.
The nature of guns required depends, like the ammunition, on the nature of the enemy's defences. There has sometimes been a tendency to think that nothing but the heaviest howitzers should be demanded on all occasions. A little consideration shows that even if the number of these natures available, and still more the amount of ammunition for them, were unlimitedconditions which are never likely to be fulfilledquestions connected with the supply of ammunition alone would necessitate economy in their use. In estimating requirements the heavier natures should only be detailed for tasks beyond the power of the lighter.
An estimate of the guns and ammunition required can, therefore, only be made after thorough reconnaissance of the enemy's system of defence, including his trenches, machine-gun emplacements, observing stations, communication trenches, rear lines, strong points, wire, &c. This reconnaissance must include not only the examination of the ground from all possible points of view, but also the reports of air observers, and a very careful study of air photographs, and of all information available in the intelligence section. The latter should give the roads used by the enemy in bringing up reinforcements and supplies of ammunition and food, the places where they can best be blocked by artillery fire, and the forming-up places likely to be used for counter-attack. The number and nature of the guns which may be brought into play by the enemy is also an important factor, as it governs the requirements for counter-battery work.* It is important that the artillery commander should make this reconnaissance in company with the general staff of the formation, and that the fullest information regarding not only the enemy's defences but his habits should be obtained from both the artillery and the infantry holding the front.
5. Scope of the artillery plan.
The general plan of attack having been settled, and information having been received that the necessary guns and ammunition will be available for the operation, the artillery commander will make out his "Artillery Plan." This should be a comprehensive statement of the objects to be attained by the artillery, and the methods to be employed. It will give the organization of the artillery for the attack, the tasks and zones of the various commands, the arrangements for communications and for the co-operation of the Royal Flying Corps, the orders regarding the expenditure and supply of ammunition, and any other points regarding the action of the artillery which it is necessary to include. Its preparation will involve a consideration of all the various tasks of the artillery during the preparation and support of the attack, but care must be taken to avoid cramping the initiative of the subordinate artillery commanders by entering into details which are within their province.
The organization of the artillery forms perhaps the most important part of the artillery plan. The principle that a divisional commander, to whom a definite objective is assigned, should have under his orders the artillery which is necessary to enable him to carry out his task, may often be inapplicable, as for instance where a corps attacks in depth and divisions succeed each other on the same front; for experience shows that any attempt to apply this principle of attack in depth to the artillery is foredoomed to failure. Now, more than ever, the guns form the "iron framework of the battle"; and all recent operations have proved the necessity for a carefully elaborated scheme for the employment of the whole of the artillery, involving a methodical allotment of tasks from the outset, and depending for its successful execution on an effective chain of artillery command.
7. Allotment of tasks. The number and variety of the tasks which the artillery is called upon to perform necessitate very careful arrangement, if the different natures are to be employed to the fullest advantage. These tasks depend upon the enemy's defences, and must, therefore, vary with the nature and extent of these. The following principles will, however, generally apply.
Although, normally, divisional artillery will remain as heretofore, both tactically and administratively, under the orders of the divisional commander, the scheme of an attack may render it advisable for the corps commander to place the general officer commanding the artillery of the corps in executive command of the whole of the artillery supporting the attack.
In such cases the divisional artilleries will still remain under their artillery commanders, and there will rarely be any reason to interfere with their organization. During the ordinary work of "holding the line" it is often very convenient to substitute "groups" of various sizes, formed to fit the local circumstances, for the established brigades, and this may in many cases be advisable, although it has sometimes been carried to an extreme not warranted by circumstances. It must, however, be remembered that there is an inherent weakness in all such improvised organizations, and that this will probably not be apparent until the unforeseen occurs (as in offensive operations it inevitably will), and the necessity for unrehearsed action arises.
The guns and howitzers allotted to counter-battery work will form a separate command as described in the note on the subject (No. 3 of this series).
The medium howitzers when employed in the destruction of first line defences have usually been placed under divisional artillery commanders, but the increased range of the newer pattern may render it advisable to group them with the heavier natures which will normally form a separate command.
As regards the heaviest natures, and all on railway mountings, the small number available and the fact that the special tasks to which they will usually be allotted are only indirectly affected by the fluctuations of the fight, will often render it inadvisable to restrict their action in accordance with the narrow front of a corps. In such cases they may be retained under the direct control of the Major-General, Royal Artillery, of the army. When, however, they are used to supplement the work of the lighter natures, as for instance when 6-inch guns are used for counter-battery work, or when the 12-inch and 15-inch howitzers are employed to destroy extra strong points in the enemy's trench system, or to bombard villages close behind the line, they should usually be combined in the same command as the other guns or howitzers employed on the same task.
An important part of the artillery plan is the co-ordination of the different artillery commands. In a corps this will mean the several divisional artilleries and the heavy artillery; in an army the artillery of the different corps, and any heavy artillery which may be retained under the direct control of the Major-General, Royal Artillery, of the army. It will include the measures necessary to ensure co-operation and to avoid any possibility of misunderstanding as to their respective zones and tasks; it will provide for the possibility of bringing heavy concentrations of fire on to particular areas if required; for cases where the heavy artillery of one corps can with advantage engage targets in front of another; and also for the fullest possible use of enfilade fire, the value of which for technical as well as tactical reasons is explained in the note on "Close Shooting in the Field" (No. 1 of this series).
10. Air observation.
Under modern conditions a great deal of the work of the artillery must always depend upon the assistance of the Royal Flying Corps, although the actual requirements will vary according to the extent to which direct observation is possible. It is the duty of the artillery commander to formulate his demands in each case, and to include in his artillery plan the arrangements decided upon: in some cases the arrangement of the guns may be decided by the number of aeroplanes which can operate simultaneously upon the front of attack. It is essential that the observers allotted to artillery work should be placed at the entire disposal of the artillery during the period of registration, as well as for the actual bombardment: close personal touch between observers and battery commanders is the secret of success.
On the actual day of the attack, and during the subsequent days' fighting, the officer directly responsible for the counter-battery work in each corps must have an observer constantly in the air. This will require at least four machines in addition to those required as escort to prevent interference with the air observers by hostile aeroplanes. A machine should also be at the disposal of the general officer commanding the artillery of the corps, ready to go up at once to obtain any special information he may require.
The Kite Balloon Sections will be allotted to artillery commands. The important point to bear in mind in connection with these is that for balloon observation an intimate knowledge of the country is the first element of success. Any change of area should therefore be avoided.
A thorough understanding of the work to be done, and of the time at which it is to be done, is essential to the success of the artillery preparation and subsequent action. The work to be done must first be divided amongst the subordinate artillery commands, e.g., in the case of a corps between the different divisional artilleries and the heavy artillery. These subordinate commanders then allot their tasks and zones to their brigades, and the brigade commanders to their batteries.
Positions will have to be found for the large number of extra guns which will be required for an offensive operation of any size, as well as probably for many of those already in action, whose positions have been selected with a view to defence. Every effort should be made to place the artillery supporting the attack as far forward as possible, so as avoid any unnecessary changes of position during the course of operations, since these must always involve difficulties in connection with registration and ammunition supply. Every precaution must be taken to conceal the fact that new positions are being prepared.
The allotment of observing stations will generally be found a still more difficult problem for the expansion required will be very great and fresh stations cannot be found in a hurry. The importance of a systematic selection and preparation of observing stations cannot be exaggerated.
All the above require a very careful reconnaissance both of the enemy's position and of the ground available, and with this object it is of the greatest importance that the various artillery commanders should get into touch at the earliest possible moment with the commanders of the infantry whose attacks they are to prepare and support. Their reconnaissances must be made in conjunction with the infantry officers, and the latter must also examine the ground from the artillery observing stations. And this joint reconnaissance on the ground must be combined with a joint study of air photographs, and of all other information as to the enemy's defences in their common zones of action, as described in paragraph 4. It is only by such means that each arm can get to understand the requirements of the other.
The value of exact and careful registration before a close and rapid bombardment is obvious. This registration, equally with the reconnaissance, must be carried out in close touch with the infantry as far as it is concerned with the enemy's defences, and this will ensure that the reconnaissance has resulted in a mutual understanding.
The longer the period over which the registration can be spread the better, and in this as in every other way possible artillery commanders must endeavour to avoid giving any indication to the enemy as regards the points of attack. The allotment of observing stations and of aeroplane observers during this period will require very careful attention. It must be remembered that even when direct observation is possible, the assistance of an air observer may often result in considerable saving in ammunition.
It is incumbent upon the artillery to take every possible precaution to prevent the enemy's fire from interfering with the execution of the task required of them. This involves making observing stations, battery commanders' posts, telephone dug-outs, and gun emplacements as far as possible shell-proof. During ordinary trench warfare observing parties can usually move if their station is shelled, and detachments can similarly be withdrawn from the guns; and it is therefore often forgotten that such procedure is incompatible with the support of an infantry attack, when the guns must be fought regardless of the enemy's fire. Unless proper protection has been provided for the observers as well as for the guns, the attempt to do so will only result in casualties to personnel and materiel, and consequent failure of the artillery to render the support to which the infantry are entitled.
15. Ammunition Supply.
The arrangements for the supply of ammunition require very careful consideration, for it is of the first importance that nothing should interfere with the movements of the infantry. During the preliminary bombardment there will be considerable traffic connected with the moving up of the infantry, and it is therefore advisable to have the ammunition required for this bombardment with the guns previous to its commencement. But this is not the crux of the problem. The real difficulties will commence on the night after the attack. The roads will then be blocked with reinforcements, ammunition, and supplies going up for the infantry, and with ambulances coming back; and the great object is to avoid adding to the congestion during this period. Every artillery unit should therefore have with it on the morning of the assault, in addition to the full establishment in its echelons, whatever ammunition it is estimated will be spent on that and the following day. It is not necessary that all this ammunition should be actually with the guns,* but it must be so placed that it can be brought up to the guns without interfering with the traffic connected with the support of the infantry. The ammunition so "dumped" must be well protected from fire and weather.
Previous to an offensive operation it will be necessary to provide the requisite communications for a much larger force of artillery than will normally be engaged in holding the line, and this requires very careful organization under army and corps supervision. The actual communications to be established in each case must depend upon the organization of the artillery. They will include, in addition to the ordinary framework in the way of command posts and observing stations, the communications required by the higher artillery commanders. These latter will be laid by the signal service, but it is essential that such circuits should be kept quite distinct from the general system. The ordinary telephone exchanges, however useful during trench warfare, are quite unsuited for artillery fighting communications during offensive operations, when all the wires will be in use at the same time.
It is impossible to take too many precautions to avoid the interruption of communication. In addition to protecting the telephone wires as far as this is possible, preparations must be made for the rapid opening of alternative means of communication. Visual signalling is the most important of these, and stations should be selected and established. Possible points in the enemy's lines should also be selected beforehand, so that, after the attack has succeeded, intermediate observers may know where to look for signals. The establishment of central stations from which messages can be sent on by telephone will prove of great assistance.
Short range wireless sets may sometimes be used where visual signalling is impossible, but in such cases reliance will usually have to be placed on orderlies, either on foot or on bicycle. Here, again, arrangements must be made in advance so that everyone may know what to do when the time comes.
17. Object of the preliminary bombardment.
The preliminary bombardment is designed to achieve a certain purpose, namely, to enable the infantry to enter and penetrate the enemy's position: for this his works and the obstacles protecting them must be adequately destroyed, and his morale shaken. The extent of the ground to be bombarded will depend upon the objective assigned to the attack. It will in all cases include, in addition to the destruction of the enemy's front-line system on the front to be assaulted, the next line in rear, and all communication trenches leading from it towards the front line. Certain areas in rear may, however, be deliberately left untouched, while the communication trenches are heavily bombarded, with the object of inducing the enemy to use this ground for bringing up reinforcements: with the same object it is generally advisable not to shell reserve billets during this period. The trenches, both front-line and support, for several hundred yards to either flank, according to the lie of the ground and the trace of the works, must be dealt with as heavily and effectively as the front of attack itself, and all salients within 1,200 yards from which flanking fire could be brought to bear must receive drastic treatment.
18. Accuracy of fire.*
The proximity of the opposing lines, and the necessity for destroying definite points in the enemy's lines, demand a meticulous accuracy on the part of the artillery never previously contemplated. The various steps necessary to ensure this are detailed in the note on "Close shooting in the field," and in older to allow of attention to these it is advisable to arrange for periodical pauses in the bombardment. During these pauses the fire should be checked by a few rounds on calibration points, equipment carefully inspected, and any slight repairs effected. Such pauses also serve to clear the air for observing officers, besides steadying the nerves of all concerned. They can well be combined with the arrangements for deceiving the enemy referred to in paragraph 22.
But the possibility of danger to our own infantry has also to be considered. The advisability of withdrawing infantry from their trenches during a bombardment depends in each case on the local conditions. If the trenches are good, and the men do not put their heads up, they may be safer in the front trenches than crowded in support trenches, which are often heavily shelled directly our bombardment opensthe nearer they are to hostile infantry the safer they are from hostile shells. At the same time the effect of one of our own shell dropping in a crowded trench, or among men creeping forward during the final bombardment, may be disastrous. The "error of the gun" must be realized, and it must be remembered that any attempt to reduce the danger by establishing a "mean point of impact" beyond the objective will seriously diminish the effect of the fire.
The duty of the artillery commander is to make these points clear to the general officer commanding; it is for the latter to decide whether the circumstances justify incurring the risks.
19. Forward guns.
In some cases guns dug in actually in, or close to, the front line trenches, may prove of great value for special purposes, such as for making a breach in the hostile parapets, or for knocking out machine guns. Provided time is available, experience shows that field guns can be got into almost any position, and that their fire at such short ranges produces a very marked effect. The methods to be employed will vary in every case, but a description of those employed on one occasion, when the conditions were particularly difficult, is given in Appendix B as an illustration of the way in which such a problem should be faced. The secret of success lies in the most careful attention to detail. Unless every possible precaution is taken, the gun and detachment may both be placed hors de combat before they have effected their purpose. Although there is no doubt that their presence has a great moral effect, their use must not be overdone, and they should not open fire until just before the assault.
20. Night firing.
As the bombardment proceeds, it is very important that the enemy should be prevented from repairing the damage done to his trenches and wire entanglements. The duty of keeping these under fire will usually devolve upon the divisional artillery, but the infantry must be called upon to assist with rifle and machine-gun fire, especially at night. Night firing on the enemy's defences may also form part of the programme of bombardment, with the object of shaking his morale; but this will require careful arrangement so as to avoid drawing fire when our own infantry are engaged in reliefs. Roads and approaches in rear of the enemy's position must, in any case, be subjected to artillery fire at night to prevent the bringing up of ammunition and supplies, and to cause casualties in reliefs. If this is carefully arranged, it may be expected to give important material as well as moral results. In view of the continuous nature of the work required of the artillery by these and other duties, it is essential to arrange that all ranks may get the requisite amount of sleep and rest.
21. Duration of the bombardment.
The time required to destroy the obstacles depends upon their nature and extent, upon the number of fire units available, and upon the facilities for observation. If the fire is to be deliberately conducted with accurate observation, so that the full effect can be obtained, the time required can be calculated with considerable accuracywith the one exception that, where air observation is required, all depends upon the weather. Shortening the period may give the advantage of surprise, and may prevent the enemy bringing up more artillery to meet the attack. On the other hand, it will entail a much heavier expenditure of ammunition of the heavier natures,* and a short bombardment, however intense, may not have the same effect on the enemy's morale as the protracted strain of some days' exposure to constant shell fire, particularly if during this period his communications are adequately blocked. Judging from the duration of the preliminary bombardments in the most important offensive operations during the past year** it cannot be said that the high road to success lies either in a short "hurricane" attack or in a protracted bombardment. The duration and character of the bombardment must primarily depend upon the strength of the enemy's works, and the artillery available for their attack, but many other factors must be considered by the general officer commanding the force, with whom the decision must rest. It is the duty of the artillery commander to place before him the technical considerations involved.
22. Character of the bombardment.
Whatever the decision on this point the programme of bombardment must be so arranged as to keep the enemy in uncertainty as to when the actual assault is coming. The German is accustomed to being drilled all his life. If, therefore, it is possible during the preliminary bombardment to drill him until he has become thoroughly accustomed to a certain procedure, and then, when the time comes, to adopt an entirely different one, there will be a very good chance of disorganizing his arrangements. Again, if he can be induced by a burst of intense fire followed by a "lift," to man his parapets, it should be possible to inflict serious losses by judiciously timed shrapnel fire, and by the repetition of such tactics it may be hoped to make him chary of leaving his shelters. Whether when the assault is actually to be delivered it should be preceded by a burst of fire of the greatest possible intensity is a matter on which there has been a gradual change of opinion. Under the present conditions of trench warfare such fire cannot be expected to cause any great effect, and it may just give the enemy the warning which he desires. The most important point is to avoid giving any indication of the intention to assault until the first line trenches have been gained. Generally speaking, therefore, it is better to keep up fire of a medium intensity up to the moment of assault, and then not to make any sudden pause or lift. In some cases success has followed an assault delivered during a period of absolute silence.
23. Progress of the bombardment.
During the preliminary bombardment it is the duty of the artillery commander to watch closely the progress of the work of destruction, and to make any modifications in the allotment of guns and ammunition which he may consider necessary to ensure the completion of the work. To assist him in this, he must arrange for the effect of the fire on the enemy's works to be continually observed by artillery officers and aeroplane observers, and must also be in constant communication with the infantry commanders concerned. A careful comparison of successive aeroplane photographs will be found to afford valuable indications.
In some cases an attack must be launched at a pre-arranged time, whatever the cost, and the responsibility of the artillery commander is then limited to doing his best to have the preparation as complete as possible by that time. But when this is not the case, it is the duty of the artillery commander to inform the general officer commanding if he considers the attack should be deferred in order to allow of further artillery preparation. The completeness of such preparation must, however, always be a relative term, and many considerations other than the purely artillery one must influence the decision, for it is a matter which most vitally affects the infantry, and it is one, therefore, on which the opinion of infantry officers must carry great weight.*
While, therefore, it is the duty of the commander of the artillery to keep the general officer commanding informed of the progress of the demolition, and to state whether he considers the attack should be postponed to allow of further bombardment, the decision as to the completion or otherwise of the artillery preparation must rest with the general officer commanding himself.
24. Covering the assault.
In trench warfare the arrangements for covering the actual assault are comparatively simple, for, owing to the proximity of the lines, the infantry will in most cases start from within assaulting distance. All that is required is that during the few minutes which will elapse while they are covering the short space between the respective lines, all points in the enemy's defences from which fire can be brought to bear are so smothered with shell as to render this impossible.** This will mean the whole front of the attack, and up to as much as 800 to 1,200 yards to either flank, according to the lie of the ground and the trace of the trenches. It is above all important that any suspected machine-gun emplacements, which have not been absolutely destroyed by the preliminary bombardment, should be subjected to constant fire, for one machine gun unattended to may jeopardize the success of the whole operation.
25. Isolating the attack.
In addition to directly supporting the attack, it is the duty of the artillery to isolate it, and so allow the infantry to consolidate their position undisturbed. For this purpose, after the attack is launched, heavy fire must be kept up on the immediate flanks and on the areas in front. It is particularly important to prevent the enemy's bombers working along the trenches from the flanks, and field guns dug in at close range, as described in paragraph 19, have in some cases proved particularly effective for blocking these. Meanwhile, the fire on the immediate front of attack must be gradually lifted. The "lifts" want careful timing, and should be very gradual, of the nature of a "creep" arranged to suit the pace at which the infantry are likely to make progress. Fire from medium howitzers can of course be kept up after that of the heavier natures, and from field howitzers later still, while that of field guns need not be lifted for a minute or two after the howitzers. Units must be told off to fire off all communication trenches, and other possible lines of approach, and on cross roads, and places where troops might be massed for counter-attack. It is especially important that arrangements should be made to cover the whole front of the new line during the night after the attack. For the second night these may have to be changed according to information obtained from observers and air photographs during the day.
The artillery must be prepared to make a barrage right across the front in case the enemy attempts a counter-attack in force, and batteries should be retained "in observation" for this purpose, and not employed on other tasks. Barrage fire must be very carefully regulated, and it must be realized that it is out of the question to keep it up for an indefinite length of time. Where the ground is under observation, it is not necessary to fire until the enemy is actually seen advancing; where the ground cannot be seen from the artillery observing station a slow rate of fire with occasional short rapid bursts at irregular intervals will probably have the desired effect. To attempt to keep up intense fire for any great length of time may only lead to the guns being short of ammunition at the moment when the attack actually comes.
27. Enfilade fire.
Enfilade fire is of particular value in the support of an infantry assault, not only on account of its great effect, but also because of the accuracy with which it can be used. If the guns placed in position for this purpose are anchored and registered accurately on the German front line when at extreme traverse, the fire can be brought back slowly as the infantry assault, by simple turns of the traversing wheel. Guns so placed can also be used to form a "cross-barrage," that is to say, one formed by guns firing at right angles to one another: whatever route is taken in the endeavour to pass through such a barrage, some of the fire must come in from a flank. It must be remembered, however, that enfilade fire must be used with caution in supporting an attack, for if it is extended over ground which the observing officer cannot see, there may be danger of hitting bodies of our own infantry beyond those which the guns are supporting.
28. Advance of the artillery.
If the object of the attack is to reach the enemy's second line, it is necessary that special arrangements should be made for supporting the further movement of the infantry. Where artillery can advance by daylight, guns must be pushed forward for this purpose, supported by the fire of those remaining in action. The units to be pushed forward must be told of it beforehand, so as to allow of their making every possible preparation* for surmounting the difficulties they will meet with. The probable order of advance should also be made out, and the responsibility for commencing the movement clearly defined. Positions and observing stations must be reconnoitred and allotted, and it may sometimes be possible to prepare emplacements, but these must be carefully concealed. Sections or single guns may sometimes be employed in this way when it would be impossible to send forward a complete battery, the section commander being placed under the orders of the commander of the battalion he is supporting.
Field howitzers are especially useful for the close support of the infantry, as they can be placed under cover in positions where field guns could not clear the crest, but it will often be necessary to move forward the medium guns and howitzers of the heavy artillery as well.
Often, however, the country will not allow of guns being moved forward by daylight. In such cases the gains required to support the advance to the second line must be dug in beforehand in or near our front line. If these guns do not open fire until the infantry have reached their first objective, it is quite possible that they will be able to maintain their position.
In the case of a corps attacking on a narrow front, with two divisions in front line and one division in reserve, it would be a suitable arrangement to use the artillery of the reserve division for this purpose. This latter division would then have the support of its own artillery for the attack of the enemy's second line.
29. Co-operation with the infantry.
The necessity of maintaining the closest possible touch with the infantry throughout the preliminary arrangements and the artillery preparation of the attack has been already insisted upon. In the support of the attack this close co-operation becomes still more essential, and at the same time far more difficult. Information as to the progress of the attack coming through infantry brigade and divisional headquarters will rarely reach artillery commanders in time to be of use. At the same time, to enable the infantry to succeed the continued support of the artillery is required, and this can only be given if the artillery are continually in touch with their progress and can direct fire at once on any points which are impeding their advance.** It is, therefore, incumbent on the artillery to take every possible step to maintain this touch, and the result of experience shows that the following arrangements are generally the most satisfactory.
30. Position of artillery commanders.
In the first place the artillery command posts must be carefully selected. Those of the commanders of the artillery of corps and divisions will usually be with the commanders of the formations to which they belong. In cases where a corps commander decides to place the whole of the artillery of the corps under the executive command of the general officer commanding the artillery of the corps, it will be the duty of the latter to maintain the closest touch with the commander of the attacking infantry, and the posts of divisional artillery commanders will be placed where they can best control their commands.
The work of the heavy artillery is so intimately connected with that of the divisional artillery that it is advisable wherever possible to establish the command posts of heavy artillery commanders in the closest proximity to those of divisional artillery. This is also the best way to ensure the heavy artillery commanders being kept informed of the movements of the infantry.
Although field artillery brigade commanders will be in many cases at first with infantry brigadiers, experience shows that any attempt on their part to move forward with the latter only leads to the interruption of their communications with their batteries. Their place is where they can best control the fire of their batteries.
Battery commanders must be where they can best see the general situation. Once the attack has been launched this changes so rapidly that there is often no time to receive orders from higher commanders, and they must be prepared to act instantaneously on their own initiative, of course informing their brigade commander of the action taken.
31. Observing and liaison officers.
Both brigade and battery commanders will require the assistance of "observing officers" and "liaison officers." The primary duty of the former is to observe the fire of their units, of the latter to maintain touch between the infantry and the artillery supporting them, and to call for artillery support as desired by the infantry commander to whom they are attached. Both classes will require their own means of communication, and forward observing officers must be provided with personnel and equipment to allow of their moving their positions.* Artillery brigade commanders will invariably attach a "liaison officer" to the headquarters of any infantry brigade whose attack they are supporting. This officer must be a man of experience and resource.
Each battery commander will usually have a "forward observing officer" to observe the fire from a forward position, to keep him informed of the general situation, and to send back all information possible.
In selecting their position these officers must remember that their business is to assist their battery commandersnot to join in the infantry fightand that their information is of no use unless they can get it back in time. Their best position will usually be the farthest point forward to which good communication has been opened up; normally battalion headquarters. Probable observing stations in the enemy's lines will also have been previously determined and allotted, and sections from these to points in the second line made from the map to test their field of view, and these will be occupied by forward observing officers as soon as the progress of the attack permits.
But as a general rule, by far the best, quickest and most accurate information has been obtained from intermediate observing stations, so placed as to be far enough removed from the turmoil of the attack, and yet sufficiently far forward to command a clear view of the ground over which it is to take place. Where ground allows, one such observing station (at least) should be established by each brigade. As explained in paragraph 2, the possibility of obtaining such observing stations is a point of first importance in forming the original plan of attack.
32. Time Table.
Circumstances may, however, necessitate the attack being carried out where facilities for observation are bad; and although various means, such as rockets, flares, flags, &c., have been tried for indicating the progress of the infantry in such cases, none have so far proved entirely successful. It is often, therefore, necessary to have recourse to a "time table," and it is then the duty of the artillery commander to draw this up. No definite rules for this can be given, except that it is necessary always to work to a "zero" which can be changed up to the last moment. An example of a time-table actually used in a recent operation is given in Appendix D, but this must be taken as a guide only, since circumstances will be different in every case. It must always be remembered, too, that the time-table depends on the movements of the infantry, and that whatever care is taken in its preparation it can hardly be expected that their movements will be so regular as to agree throughout with any forecast. A time-table has often worked well during the very early phases after the assault, but the time must come when it can no longer be followed, and all ranks must be prepared for this. It is important that infantry officers should be acquainted with the time-table.
33. Use of gas and smoke.
Gas and smoke may be used in different ways in an attack. In some cases gas clouds are projected from cylinders, in others smoke and gas bombs may be fired from trench mortars, or gas shells fired by the artillery. Any one of these different methods may be resorted to, or they may be used in combination, but since gas and smoke bombs do not form part of the equipment of the trench mortars manned by the artillery, it is with the gas shells only that the artillery is directly concerned. The use of gas and smoke in other forms, however, may effect the action of the artillery, and must therefore be referred to here. The first point to remember is that owing to the possibility of the use of gas or smoke having to be abandoned at the last moment on account of changes in the weather, no abatement in the thoroughness of the artillery preparation should be made on account of the fact that the use of these aids forms part of the general plan of attack. They will only affect the action of the artillery on the day of attack.
34. Combination of artillery fire with gas or smoke.
The idea that high explosive shell should not be used against those parts of the enemy's line on which a gas attack is directed, for fear of dispersing the gas, may be dismissed. Far from reducing the effect of the gas, shells bursting among it may be expected to increase it by forming eddies which will allow of the gas sinking into the enemy's trenches, dug-outs, &c. There is, therefore, no reason to reduce the H.E. fire of the artillery on account of the use of gas. Shrapnel fire may also be expected to be very effective in combination with smoke and gas, as these will probably cause the enemy to man his parapets, and in some cases to come out into the open.
The use of smoke, however, adds to the difficulties of the attacking artillery, since it interferes with observation of fire, and also of the progress of their infantry. When smoke is used on the front of attack, the artillery must therefore work to a time-table, the disadvantages of which have already been pointed out in para. 32.
As regards effect on the enemy's artillery, it is impossible to interfere with their ability to "barrage" our front line trenches, but the smoke will prevent their knowing the time and point of attack, and therefore will interfere with their power to concentrate upon it. It will also interfere with their power to bring fire on our infantry once they are through the front line barrage, as it will conceal their progress from the enemy's observers.
35. Description of gas shell.
It is, however, in the use of gas shell that the artillery is chiefly concerned. The body of these shells is filled with a chemical liquid (S.K.) which is scattered over the ground as soon as the shell bursts, and then slowly vapourises. The vapour produces intense irritation of the eyes and respiratory organs. It is not poisonous, but those handling the shell, especially in the case of one showing a suspicion of leakage, should be provided with protective goggles, and should at all costs avoid rubbing their eyes with their hands. The bursting charge is only sufficient to open the shell, so that the penetrative effect of the splinters is very much less than with the ordinary shell.
36. Action of gas shell.
The vapour of S.K. is seven times heavier than air, and will therefore remain close to the ground, filling trenches, dug-outs, cellars, covered gun emplacements, woods and hollows. The radius of action of this type of shell depends almost entirely on atmospheric conditions, especially wind. The shells will produce their minimum effect
The most favourable circumstances for use are when there is
The effect is particularly marked in valleys, or small woods, and in forests the shells may be employed even when a strong wind is blowing outside.
In the open, on a damp and muggy day with little wind, the effect may last for six hours or more, whereas on a dry clear day, with a breeze, it will probably not persist for more than 30 minutes. In woods, buildings, or covered emplacements, the effect may be felt for as long as 24 hours.
37. Gas barrages.
Gas shells may be employed against a position which it is desired to deny to the enemy for a certain length of time, or to create a barrage through which the enemy's troops cannot pass. To get the best effect it is always advisable to select ground which favours the use of gas, such as for instance a valley, wood, or village. If a gas barrage has to be formed in the open it should have a depth of from 150 to 200 yards. It must always be borne in mind that the fire may have the effect of preventing our own troops from occupying the ground for some hours, or even, in some cases, of traversing it.
38. Counter-battery work.
The chief value of gas shells is, however, for counter-battery work, for which they possess certain decided advantages over the ordinary shell. The gas sinks into the dug-outs; it affects the whole of the personnel; and most important of all, it renders the position untenable for some time. Even if efficient protective masks are available, these will almost certainly considerably interfere with the service of the guns. Moreover, by taking advantage of the wind, effect may be obtained, even if the position of the guns has not been located with the accuracy that is required for obtaining direct hits on gun emplacements; and the effect will be most marked when the guns are concealed in woods, houses, &c., where they are least vulnerable to ordinary attack. Gas shell may also often be used with great advantage against artillery observing stations.
39. Method of using gas shell.
The quantity of vapour of S.K. necessary to produce an effective cloud can only be obtained by firing a large number of shellwith the 4.5-inch, cast-iron shell at least one round for every two yards of front. The fire should be rapid until the necessary cloud has been produced, after which a slow rate will be sufficient to maintain it. Even when the gas shell contain some smoke-producing substance, ranging should be carried out with the ordinary shell, so as to give the enemy no warning of what is coming. To cover a zone really efficiently the fire must be methodically distributed, and the following extract from a captured German document is a good example of how this may be done:
The four guns of a battery are so placed that with parallel lines of fire they will cover a front of 50 metres with their fire. A series of four rounds per 50 metres of front will be fired. The area to be covered is then searched in zones 50 metres wide and 25 metres deep, so that no gaps are left. The barrage should first of all be established along its whole width and the range should not be increased until this has been effected (see Fig. 1).
The sequence in which salvos are fired will depend on the direction of the wind, the nature of the hostile positions included in the area to be shelled, and also on the intentions of our own troops. With a west wind, for instance, the salvos will begin from the west; if our infantry intends to advance later towards the area in question, our salvos will begin on the near edge of the area.
Calculations should be indicated on a diagram, the width and depth of which are proportional to those of the target. Thus Fig. 2 represents a barrage fire against a ravine situated obliquely to the angle of fire. In order to retain control of the fire, even during the procedure of searching, the artillery commander has a similar diagram, which enables him to change rapidly the method of searching in accordance with either his own observations or the reports he receives. He has only to indicate the numbers of the salvos (omit certain salvos or else order a new series at given points).
40. Combination of shrapnel with gas shell.
The combination of shrapnel with gas shell, if judiciously used, may be expected to prove very effective. For instance, if troops concentrated in villages, woods, or assembly trenches are being attacked with gas shells, the ground in rear and on the flanks should be swept with shrapnel at the moment when it may be judged that the gas will have had time to drive them from their cover. The same procedure should usually be followed in counter-battery work.
41. Counter-battery work, wire cutting, and trench mortars.
In the above little reference has been made to counter-battery work, to wire cutting, or to the use of trench mortars. This is because these are all fully dealt with in separate notes. Nos. 3, 5 and 6 of this series.
In conclusion, it only remains to say that while experience points to the procedure outlined in this note as being the best calculated to secure success, the details will vary with every case. Before forming their "Artillery Plan," on the soundness of which the success or failure of the whole operation may so greatly depend, it is incumbent on artillery commanders, while giving due weight to local circumstances, to consider carefully the principles here laid down for their guidance. But, however complete the plan may be, it is only by the most careful attention on the part of all ranks to every possible detail during preparation, and by the exercise of discipline, self-sacrifice, and a determination to win during execution, that success can be assured.
The following notes will be of assistance to artillery commanders in making their estimates :
On any one day the number of rounds from field guns and howitzers can be considerably increased.
The following is only intended as an example. The particular method employed must vary with circumstances in each case. For instance, on one occasion, where a gun was placed between 150 and 200 yards from the German trenches, an ordinary canvas screen was put up just in front of the position selected. The Germans were allowed to get used to this, and a sandbag emplacement was then built behind it. When the time came for the gun to open fire the screen was not removed but the gun fired through it. In another case it was found when firing a registering round that the gun could not get at the German parapet without hitting our own. No gap in our parapet was however made as this might have invited attention and disclosed the presence of the gun, but on the day of the attack the infantry were cleared away from that portion of our trench, and the gun with its first two or three rounds breached our own parapet, and then dealt successfully with its target.
Example. Preparatory arrangements.
The actual position was finally selected six days before the attack. It was not exposed to any hostile observing stations, or to flanking rifle or machine gun fire. Accurate measurements of the trench were taken, and a facsimile trench was dug at the battery wagon line.
In conjunction with an engineer officer, the form of emplacement was decided upon. The chief point consisted in the provision of a wooden box, with a sloping hinged front, which was to be built into the parapet. (See diagram.) The facsimile emplacement was prepared accordingly, the gun placed in it, and gun drill assiduously practised (including live shell practice) by the detachment, which was composed of volunteers. Gun and sights were carefully tested, and all ammunition to be used was tested for gauge in the bore to guard against jams.
As a canal had to be crossed to reach the position a pontoon raft was prepared to carry the gun, and a thorough reconnaissance of the whole route was made. A small stream which intervened was bridged, and ramps were cut on both banks of the canal.
When the gun position had been fixed definitely, a back angle was taken to an aiming point so that the gun could be laid before the box was opened.
Occupation of the position.
Two nights before the day of attack the gun was driven down to the canal bank, being halted whenever flares were fired. It was then manhandled and rafted across the canal, and carefully concealed on the further bank, with its ammunition placed in a dug-out. Infantry assisted in this.
Concurrently, the digging of the emplacement was commenced under R.E. supervision. Wheel tracks, a foot deep, were cut for the last 30 yards of the approach to the position to give better cover. Dug-outs were prepared and strengthened for the detachment and ammunition. The epaulment was completed during the following day.
The second and final stage was carried out on the night immediately preceding the attack.
Firstly, the wooden box was inserted into the parapet. To effect this the parapet had to be pulled down on a front of about 5 ft., and to cover this gap a canvas screen was erected in front. When placed in position the box was covered with sandbags and earth, and the parapet re-built round it.
The gun and ammunition were then brought up and placed in position. Three communication trenches had to be crossed, and planks were laid for this purpose. They were not filled in so that their use by infantry might not be obstructed. In bringing up the gun a canvas canopy was carried over it, and the detachment was trained to fall flat whenever a flare went up, dropping the canopy over the carriage to hide it.
The artillery fire attack opened at 5 a.m. Covered by a salvo from a trench mortar battery in action close by, the gun opened fire and fired its 100 rounds in 9 minutes. The range was 70 yards and the objective was to destroy a T-head and the knife-rest wire by it. The T-head appeared to be demolished with the 50th round, after which the fire was directed against the knife-rests of wire. The latter were extensively piled up, being taken in enfilade.
No casualties occurred during the firing, and, as soon as it was over, the detachment was withdrawn to cover in its dug-out. The gun was withdrawn on the night following the day of attack in a similar way and without loss.
The thick lines indicate the wooden box in section as placed in the parapet. At A were the hinges round which the front of the box, AB, swung when pushed front rear; the remainder of the box did not move.
LINE TO BE BROKEN THROUGH. Q 2 TO V 6
At 0.40 Infantry assault and push on to the line Fme. Cour d'AvoueFme. du Bois. It is assumed that the Infantry make good the line P 8, P 10, Q 12 and the road thence to le Tourelle at 1.15.
Further advance after 1.15, i.e., the occupation of the line la Quinque Ruele Tourelle.