Translation of a Memorandum, dated 11th July, 1915,

Translation of a Memorandum, dated 11th July, 1915,
drawn up by General CASTELNAU, Commanding the Group of Armies
of the Centre.
The Commander-in-Chief in a recent memorandum laid down general principles to be applied and the steps to be taken to deal with the type of attack as practiced at present by the enemy.
These attacks are invariably preceded by a heavy and prolonged bombardment.
Experiments carried out both by ourselves and by the Germans lead one to the conclusion that it is merely a question of employing the necessary amount of heavy artillery in order to ensure the destruction of hostile trenches. Defensive organisations are demolished. Judiciously placed shell-proof casemates and subterranean dug-outs, of which the Germans have rightly made such extensive use, are alone capable of resistance.
Hence it is no longer a question of spreading men all along a line which was considered proof to any attack; it is necessary to keep a large proportion of them in hand so that they can be brought up wherever they may be required.
For an army acting on the defensive the battle has only begun, when the enemy has crossed the front trenches. It lies with the Commander to have in hand the necessary resources in infantry and artillery, to enable him to intervene at the right moment.
Therefore, Army Commanders should take the necessary steps:-
1. To diminish the numbers in occupation of the front line trenches. The onus of defence should fall on small groups, judiciously distributed, supported by machine guns. The number of observation posts, shell-proof flanking casemates and subterranean dug-outs should be increased.
2. To organise sector reserves along the whole front.
3. To keep in reserve complete formations which can be easily moved.
4. To be able to reinforce rapidly the artillery on the front attacked. This implies the preparation of numerous emplacements, the allotment of zones of fire in advance, (destruction of enemy trenches and counter-batteries, tir de barrages.)
But it is not sufficient to pre-arrange the composition of sector and army reserves; it is essential that they should be able to come into action when and where they are wanted.
As a violent and continued bombardment, which is intended to destroy the front lines, generally begins one or more days before the attack proper, the local commander can anticipate this and make his preparations accordingly.
If the front line trenches are demolished, their garrison will be transferred to swell the numbers in the support trenches or redoubts and “points d’appui” situated to the rear. (Defensive organisations in depth are essential).
It is here, that it will be possible to check the enemy’s attack and to counter-attack so as to drive the enemy back. The success of a counter-attack depends on surprise and determination.
If delivered by the sector reserves, it must take place immediately. This is feasible:
1. If the details of execution have been minutely prepared in advance.
2. If these reserves are thoroughly familiar with the sector.
3. If their moral is unshaken (this entails their being kept immune from bombardment).
4. If they are well provided with grenades.
5. If our own artillery has kept up a continuous fire on the trenches which have been lost in order to prevent the enemy from establishing himself there, and has opened a tir de barrage to prevent the arrival of supports.
The counter-attack, carried out by Army reserves, should be as rapid as possible. For this purpose it is necessary to have studied and prepared their mode of action and employment in good time.
The enemy should not be allowed time to reorganize on the ground they have occupied, otherwise the whole thing will have to be started afresh like an ordinary attack against an organized front, which requires working out and preparing in every detail.
In order to use reserves in this way, it will be necessary:-
1. To have been able to withdraw them, if possible, from the effects of the bombardment and of the asphyxiating gasses (numerous alarm posts and shelters).
2. To be able to use them in spite of the enemy’s tir de barrage, (a study being made beforehand of their mode of employment; numerous communication trenches, a proportion of which will be strictly reserved for evacuation of wounded, dividing the ground into sectors etc.)
3. To have foreseen and prepared the action of the batteries specially entrusted with supporting the counter-attack (reinforcing batteries, preparation of emplacements, allotment of zones of fire etc.)

Whether carried out by Sector or Army reserves, the counter-attack must always be driven home. Exploit to the full the confusion and disorganization likely to arise in the enemy’s ranks, in order not only to drive him back to his own line but also to gain as firm a footing as possible in the hostile trenches.
An Army should deal with an attack delivered by a few brigades with its own reserves, without having to draw upon the reserves of the group of armies. The employment of the latter is worthy of consideration for such tasks as penetrating still further into the enemy’s position in the track of the Army reserves, and breaking the front, if opportunity offers.

The last page/pages are missing.

Co-operation scheme 11 July 1918


1. Introductory. Whether the move is an advance or a withdrawal, the problems to be solved are much the same: the latter case however, is the more difficult operation, and is herein dealt with. The principles can be applied to an advancing battle mutatis mutandis.

2. Role of Squadron. Provided Liaison with the ground can be efficiently maintained the functions of the Corps Squadron are properly –
(1) Battle Reconnaissances.
(2) Artillery work with surprise targets.
(3) Liaison Reconnaissance to identify, and communicate to with other Arms.

Systematic bombing and shooting up of live targets is more properly the role of Army Squadrons and reinforcing Brigades.

3. General Idea. If these duties are to be carried out, it is essential that the energies of the Squadron should not be taken up by moving daily from place to place: a situation must therefore be taken up well in rear, and touch kept with other Arms by means of advanced landing grounds occupied in turns.
A Map of all feasible grounds (in rear of a large sector of the front, to legislate for possible cases of divergent lines of retirement) should be compiled by R.A.F. Brigades, kept up to date, and issued to all concerned. If this is not available, the duty of selecting suitable sites, lies with the R.A.F. Officer attached to a report centre.

4. Main Report Centre. The first essential is to establish a Main Report Centre (M.R.C.) in close proximity to Corps H.Qrs. (Advd H.Qrs): It is a sine qua non that this Centre should be on a practicable landing ground.
This M.R.C. would be in charge of the Corps Squadron B.I.O., and its position notified to all units (if necessary by message dropping). All aeroplanes of the Squadron would land in the early morning at this Centre, and function from there throughout the day, returning to the base aerodrome in the evening.
A Wireless Station, a few small spares, petrol and oil, and a Corps D.R. service, would be installed at this M.R.C.

5. Move of M.R.C. In the event of Corps H.Qrs., continuing to move backwards a new landing ground will be taken up, and if possible installed before the first ground was abandoned. (see 7 below)
As soon as a move is contemplated an arrow would be put out near the T on the landing ground, pointing in the general direction of the new site. When the forward ground is finally vacated, the T is taken up, and the arrow left out.
It is hoped by this means to ensure constant Liaison between Corps and Squadron H.Qrs.

6. Artillery Work. Fire on targets notified from the air will largely be the task of the Divisional Artillery. Owing to the withdrawal of the bulk of Siege Batteries, and to the lack of means of communication from Corps H.A., to batteries, it is likely that H.A. H.Qrs., and the C.B.S.O. will cease to operate with large formations, and that their position will approximate to Corps H.Qrs. Mobile Heavy Artillery Brigades will be attached to Divisional Artillery.
All units must remember the absolute necessity of moving the personnel and material of their Wireless Station, and of erecting same whenever possible.
Artillery Units ready for action with aeroplanes, should keep out the ground strips of their calls, except in presence of Enemy Aircraft.

7. C.W.S become A.R.C. When Corps H.A., H.Qrs., ceases to function tactically the Central Wireless Station (C.W.S.), will remain as an advanced report centre (A.R.C.), for work with Divisions.
It will be under the charge of one of the Squadron wireless Officers, and will be equipped in the same way and will function in the same manner as the M.R.C.
When withdrawal becomes necessary the A.R.C., will move past the M.R.C., and will take up its position near the new Corps Advd H.Qrs., where the B.I.O., will again take command, it will thus become itself the Main Report Centre, while the old M.R.C., becomes the A.R.C.
One of these two Stations is thus likely to be in action and both will have landing grounds in their vicinity.
Communication between M.R.C., and the A.R.C., will be maintained by wireless.

8. Liaison Reconnaissances. The services of the R.A.F., will be of extreme value in identifying and reporting positions of unit Headquarters: they supplement other means of communication in this respect, or at times supplant them in the absence of telephone facilities, and during periods of road congestion. An efficient Air Service should be able to keep the Corps Commander informed of the position of his units and should be able to transmit his orders to them.
A whole Flight should be detailed for this important service (This Flight could reinforce the Battle Reconnaissance or Artillery Flight in the event of the withdrawal being premeditated and leisurely).
Every H.Qrs., should be provided with ground strips to form a two or three letter code call (only those letters should be used which can be formed into straight strips) and a Popham Panel. The code calls should not be arbitrary, but should have their index letter such as to indicate to the aeroplane, the nature of the formation to which they belong.
The Observer would then know for instance, that he had located 2 out of 3 Divisions – could inform a Division of the situation of a neighbouring H.Qrs., etc. etc., by means of message bags. (See Note).
If the importance of carrying and displaying these strips is impressed on units, it should be possible for an aeroplane flying over an area and calling by means of Klaxon Horn, or Very’s Lights, to rapidly accumulate valuable information as to the positions of units throughout the day.
This form of Liaison should be infallible, whereas, Wireless inter-communication may fail owing to lack of experience, delicacy of instruments, lack of trained signallers, running down of accumulators, etc.

9. Attachment of R.A.F. Observers to Formations. In order that the possibilities of Aerial Co-operation outlined above may be taken full advantage of, it would appear essential for a proportion of the Observers of a Squadron to live, and move with units of the Corps.
It is suggested that:-
2 Liaison Officers should be attached to Corps H.Qrs.
1 Battle Reconnaissance Observer to each Divisional H.Qrs.
1 Artillery Observer to each Divisional Artillery H.Qrs.
These Observers would be informed by the unit Commander, as to what particular information is desired: they would then proceed to the nearest Report Centre, and pick up the aeroplanes detailed for the service. It must however, be pointed out, that the R.A.F. cannot provide transport for each of these Observers. The essential principle of the whole scheme proposed, is that it should be possible to carry it out with the means at the disposal of every Corps Squadron in the Field, and the transport allotted is barely sufficient for present requirements.
If units desire the services of an attached Observer, they must when occasion demands, find some means of transport, horse, bicycle, motor bicycle, etc, to enable him to reach the nearest aeroplane landing ground.
The information obtained by these special Observers, though primarily for the benefit of their own formation, will be in every case transmitted to the M.R.C.: the Pilot will be responsible that this is done when the aeroplane lands on the advanced instead of Main Report Centre.

10. To sum up the essentials of the scheme proposed are:-
(1) A rearward location of Squadron aerodrome, and Administrative H.Qrs., to avoid constant movement and road congestion.
(2) Forward tactical landing grounds.
(3) The division of the Squadron into Battle Reconnaissance, Artillery, and Liaison Flights.
(4) The utilisation by of all units of ground strips to denote their positions.
(5) The attachment of R.A.F. Observers to units for Liaison work.
(6) No extra transport or material required, beyond that now in possession of Corps Squadrons.
(Details as far as at present worked out, are attached).

J.A. C****
Lieut Colonel,
Commanding 15th Wing,
Royal Air Force.
In the Field.



1. Wireless Stations. It is most important that all wireless stations held by artillery units should be used to their fullest extent. It should be realised by all concerned that the wireless station must be erected at the very first opportunity and not left to be erected until after arrangements for every other means of communication have been made.
Close co-operation with aircraft is of vital importance during a moving battle, as few batteries have wire oft time available to ensure good communication with ground O.P’s and aircraft are the first and frequently the only means of discovering concentrations of the enemy just prior to an attack. If all units have wireless sets working, such concentrations can be successfully dealt with by means of LL and GF calls. During the last withdrawal some such concentrations were successfully fired on and dispersed in this manner but in a great many cases wireless was not working at the critical moment and opportunities of inflicting heavy casualties on the enemy were missed. In many cases for lack of any other means of attack such concentrations have been dealt with by means of bombs and M.G. fire from the air.
It is of course impossible during hurried changes of position to avoid the loss of a certain amount of material but – once the vital importance of a serviceable wireless set is realised by all – it should always be possible to bring away the essential parts of a wireless set i.e. tuner, aerial and earth mat. Masts, if lost, can always be improvised by using trees, buildings or even short R.E. signal poles. A sheet of corrugated iron can be used to replace a missing earth mat or at a pinch any metallic earth such as a jack knife or earth pin can be utilised.
Efforts are being made to reduce the weight and bulk of a wireless station so as to render it more easily portable by Field Artillery units; even at present the essential portions, referred to above, can and should always be carried in the firing battery. They will then be immediately available and the station can normally be ready to take in messages within a few minutes of guns getting into action.

2. Field Artillery. Field Artillery during a moving battle will form a large proportion of the available artillery for engaging surprise targets. As Brigade Commanders may be out of communication with a proportion of their batteries, it is essential that as many Field batteries as possible should be equipped with wireless stations. This can only now be done by withdrawing stations from Siege batteries when no longer required. Squadron Commanders should make early arrangements with their Corps H.A. to withdraw the stations from those Siege batteries which are least likely to require them and reissue them to R.F.A. brigades for allotment to batteries. This must be done under Corps arrangements as R.A.F. transport is inadequate to deal with the situation.

3. Map references and calls from the air. The importance of having squared maps of the back areas ready marked up with zones has been touched on above: without security on this point Artillery will hesitate to fire and golden opportunities will be lost. Another cause of trouble is here dealt with. Owing to the small amount of wireless sending going on calls have in past moving battles been picked up from two map sheets away: the danger of this will be readily seen as the correct zone will not preclude the possibility of the call being taken in and acted on by batteries who should not have been affected: it is essential therefore in moving warfare for the Squadron call to precede any signal sent from the air including SOS, LL, GF, and NF, calls. The Squadron call and battery calls will remain unchanged during the whole period of movement.

4. Message Dropping. Pilots must not hesitate to use message bags to indicate favourable targets to our guns if the wireless produces no response: this practice has a great future before it. Pilots must not forget that if by any means concentrated artillery fire can be brought on to living targets far greater effect will be produced than by a few small bombs.

J.A. C****
Lieut Colonel,
Commanding 15th Wing,
Royal Air Force.
In the Field.

Note II on LIAISON WORK,CALLSIGNS etc. 11 July 1918


X = Corps Headquarters Station, i.e. Main Report Centre.

X = Divisional Dropping Station sign, as authorised.
Divisional calls might be
DX) (Note D is formed by strips)
So that in event of loss of some strips the letters above would indicate a Division.

= Brigade Headquarters as authorised, and calls might be
WX) for W Division’s Brigades.

XX) for X Division’s Brigades.
Etc., so that in the event of loss of the special signal the letter alone would indicate a Brigade.

D = Battalion Headquarters and call signs might be any starting with earlier
letters of the Alphabet, so that in the event of the special sign being lost they would still be recognised as Battalion Headquarters though the Division would not be known to the Airman.

All Artillery formations to which calls are allotted will use the prefix N if not in action as regards aerial observation, L if they are ready to fire with a plane.

All Infantry formations will display their signals as usual on the call by aeroplane of a series of A’s on KLAXON and a white Very Light.
All Artillery formations will display their signals as usual on the call by aeroplane of a series of B’s from KLAXON and a green Very light.

Strips of formations at some distance from the battle line will be more visible if a flare is burnt near them or a smoke fire lit.

A special unit may be demanded by its call letters on KLAXON
The aeroplane will acknowledge having seen strips by repeating the call letters with R.D. or by diving on the strip.

Popham panel work will be carried out as usual with the accepted code.

Any formation which is about to move should put out its strips and add an arrow to its strips giving the direction in which it will proceed.

N.B. the French System of Ground Panels has much to recommend it. It is reproduced below:-







(Each sign is 3 metres over its maximum diameter Squares or bands 4 centimetres wide)

J.A. C****
Lieut Colonel,
Commanding 15th Wing,
Royal Air Force.
In the Field.




All possible arrangements as detailed below must be worked out beforehand, so that as soon as orders are received by S.C. “Moving warfare action” he can take the following measures, (Orders for move of Squadron to rear aerodrome will be issued by the Wing). –

1. Turn 1 Artillery Flight into a Liaison Flight.

2. Issue to Flight Commanders for distribution (if not already done) squared maps of the rear areas. These must have been previously marked up with the zones e.g. QA, QB, QC, QD or KW, KX, KY, KZ, etc. If this is not done, Pilots may get careless once they get off their C.B. Map, and will send Zone calls with the wrong Zone with disastrous results. All Pilots and Observers must be cautioned to be careful in this respect.

3. Despatch 1 Light Tender to C.W.S. with 3 Artillery, and 3 Reconnaissance Observers for attachment to Divisional Artillery, and Divisional H.Qrs.
All personnel will have two days rations, tin helmets, gas masks, and a minimum of kit (not exceeding 30 lbs).
All ranks must know what their duties are, to which unit they are attached, and where it is situated. Any spares required to complete the C.W.S. to the standard A attached (establishment of M.R.C., or A.R.C.) will be taken on this tender.
At least 20 gallons M.T. petrol, and 2 gallon M.T. oil, will be carried. A rifle and 100 rounds S.A.A. will be taken. Any spare space will be filled with aero petrol and oil.

4. Despatch 1 Light Tender and 1 motor bicycle with S.C. to Corps H.Qrs., with B.I.O., and limited staff, (2 men), and 2 Liaison Observers. This is to form the M.R.C.
Other details as above.

5. Arrangements for all aeroplanes to operate from Main Report Centre as soon as established – Pilots travelling solo to load up with petrol and oil in cans, and ammunition in drums and belts. – a fitter and a rigger with a few tools and patching material to be sent over with the first planes of each flight daily, returning at night – tail weights to be provided for solo work.

6. The administration of the Squadron must be largely left in the hands of the R.O., and E.O. – the Squadron Commanders place by day is mostly at the M.R.C., in close touch with his Corps and his aeroplanes.
J.A. C****
Lieut Colonel,
Commanding 15th Wing,
Royal Air Force.
In the Field.
Main or Advanced Report Centre.


Mast 30 Ft. complete.
Tuner, short wave Mk. III.
Canvas carrying bag.
8 Ground Strips.
125 ft. Aerial Wire.
2 Insulators.

Weight of above approx 120 lbs.

Could be packed in a space 4’ 6” x 16” x 16”

C.W. Transmitting and Receiving.

Mast 30 ft. complete.
150 ft. Aerial Wire.
2 Insulators.
3 Sets of accumulators.
Wavemeter. Hetrodyne.
H.T. Unit or H.T. Batteries.
Weight of above with H.T. unit – 163 lbs.
Weight of above using H.T. Batteries instead of H.T. unit 197 lbs.


One pair of Earth Nets would do for both stations.

1 Officer, and 4 Operators – a few spares – Time token to erect – ½ hour.
dismantle ½ hour.

1 B.I.O. and 2 Clerks for M.R.C.



1 Motor Cycle and Side car.
1 Light Tender.