Lessons Learned at Dieppe (V)

Airborne Troops, Smoke, Light Artillery

369. The Use of Airborne Troops

(a) In the original plan for the Dieppe operation Airborne Troops were included to deal with certain important batteries.  In the final plan for the operation they were omitted. 

The participation of Airborne Troops calls for certain weather conditions, especially as far as light is concerned, and in so doing increases the odds against a particular operation taking place within the favourable period for moon and tide. 

In this respect the Dieppe report makes it clear that though the conditions on the day of the attack were satisfactory for ships and landing craft, they would not have permitted the use of Airborne Troops at the time required in the original plan. In fact, weather conditions suitable both for landing craft and Airborne Troops did not occur at all during the period. Thus, had the latter been included, the operation would have had to be cancelled. 

(b) It should be observed, however, that technique, equipment and methods are continually improving and that conditions which would be considered hazardous or impossible today may become far from impracticable in a few months time. 

It is considered that the correct deductions to draw are the following:

(i) Airborne Troops provide a means of achieving surprise and of getting over difficulties both literally and figuratively which other arms do not possess. They should, therefore, be included in plans as often as possible.

(ii) However, so long as the present weather limitations apply, it is advisable that Airborne Troops should not be allotted to tasks of such importance as would entail the cancellation of the operation if adverse “airborne weather conditions” prevailed.

Thus, they should be employed on tasks which, though extremely helpful, are not vital to the plan as a whole. If so used, then their possible non-participation will not necessarily mean the cancellation of the entire operation. It should, however, be borne in mind that the tendency of recent inventions is to overcome the main obstacle—the necessity for suitable light conditions—to the use of Airborne Troops. The new navigational aid is now giving most satisfactory results and, provided one or more men can be landed before the operation, troops can be dropped accurately under almost any light conditions.

(iii) The question of briefing and "sealing” of Airborne Troops and their aircrews must be taken into consideration when deciding whether to employ them.

(iv) Close touch should be kept with Airborne formations so that those responsible for preparing plans are kept aware of all progress made and of the weather and light conditions in which improved methods and equipment may allow them to operate.

370. Choice of Assault Landing Places 

(a) The choice of assault landing places is limited principally by the tidal conditions at the time of the landing, the beach gradients, and the exits from the beaches. In addition, the time that can be allowed on shore has a direct bearing on the choice of landing places in raiding operations of comparatively short duration.

(b) It is considered, however, that whenever the conditions permit the assaults should be planned to develop round the flanks of a strongly defended locality, such as a town, rather than frontally against it. 

(c) It is recognised that the defences along the whole occupied coast are becoming formidable. But the intense difficulties caused at Dieppe by well-concealed and reinforced positions in houses, by road-blocks and obstruction walls are very evident from the report on the operation. The landing places at Dieppe were peculiarly difficult, for in addition to the frontal defences they were flanked by high cliffs from which coast defence guns and other arms maintained heavy enfilade fire. These defences could not be neutralised by the bombardment, bombing, or assault landings. What happened at Dieppe points to the wisdom of avoiding frontal attacks on such areas whenever possible. 

Naturally, the situation would be radically altered if very powerful fire support was available during the early stages, or if the defences had been subdued by action before the assault, but in the absence of such support or preparatory action it will be wise to envelop a strongly defended locality rather than to make a frontal attack upon it. 

This by no means excludes a frontal feint staged in order to fix the enemy’s defences and perhaps his reserves as well. On the contrary, every form of feint deception and diversion should be practised in order to mislead and confuse him during the all-important period when the leading troops are being landed and are fighting to make good their bridgeheads. 

371. Aircraft Recognition 

(a) During the Dieppe operation, there were many cases of our own aircraft being engaged by our own guns. Such incidents are always likely to occur in the heat of an action, but every possible step must be taken to reduce them to an absolute minimum. 

(b) The following measures are recommended :

(i) The early issue to all ships and units of photographs and silhouettes showing the types of aircraft which will be acting in support of the operation, and of enemy aircraft likely to be seen. Lectures should also be given as frequently as opportunity offers. 

(ii) Arrangements to be made for aircraft of the various types to fly over ships and units during training and rehearsals. On such occasions personnel of the Royal Observer Corps should, whenever possible, be present so as to indicate the type and the distinctive features by which it may be recognised.

(iii) During the operation itself, it will be invaluable if specially trained personnel (possibly from the Observer Corps) can be allotted to ships and landing places so they are available to distinguish friendly from hostile aircraft at the earliest moment. 

(iv) Pilots to be instructed to avoid as far as possible flying straight at ships, as the guns’ crews are bound to treat all aircraft flying straight at their ship as hostile. 

(v) The greatest possible use should be made of the present schools for aircraft recognition established at the various ports. 

372. Landing of Beach Organization Personnel 

(a) Beach parties at Dieppe were put ashore as complete detachments in the first flights with the object of getting the landing places organised from the earliest moment. 

(b) In practice, however, it was found that the landing of complete beach parties had two major disadvantages. The first was that their presence meant leaving out an equivalent number of the leading sub-units. The second that, if, as happened, the action did not proceed according to plan, the beach party was likely to become embroiled in the fighting ashore and as a result to suffer casualties which might be great enough to prevent it functioning as an organised body for some considerable time. 

(c) It is recommended, therefore, that beach signal organisation personnel including beach parties should be distributed evenly between the escorting craft for each Group of landing craft and that it should be the Beachmaster himself, in one of these craft with the Beach Signal Officer, who should decide at what time the various elements of beach organisation personnel parties can safely be landed. Situation reports from reasonably close inshore could then be passed before they had landed. 

373. Protection During Passage

During its progress across the Channel, the force attacking Dieppe was very vulnerable to surface attack. None, in fact, developed, but it will be imprudent to assume that such a risk can again be taken with impunity. It is therefore necessary for a heavier Naval escort to be provided than was available for the operation against Dieppe.

374. The Use of Smoke

(a) Given reasonable atmospheric conditions smoke properly used can be a very valuable aid to a combined operation. It can, nevertheless, become a double edged weapon if its employment is not most carefully planned between the three Services.

(b) At Dieppe, for instance, it might have been helpful in order to cover the landing craft during the final stages of their approach, and the initial stages of the landing itself, to have ended the Naval bombardment of the central beaches with some salvoes of a smoke shell or, alternatively, to have laid a curtain of smoke across the front of the town by aircraft. If, however, smoke had been put down by either of these methods, then the cannon fighters could not have gone in to make their attacks just before the landing, and in the case of smoke laid by aircraft, bombarding ships would probably have lost sight of their targets too soon. The comparative advantages of a fighter attack and no smoke as against a smoke screen and no fighter attack had to be weighed and a decision reached. This isolated incident appears an excellent example of one of the numberless points directly affecting all three Services which inevitably crops up during the planning of a combined operation and which can only be settled by joint consideration and a joint decision on the part of the Force Commanders.

(c) The conditions for smoke during the Dieppe operation were excellent and the following methods were employed for producing it:

(i) by special smoke apparatus (Chloro-Sulphuric Acid) carried in certain ships and craft;

(ii) by smoke-floats carried by ships and craft;

(iii) by aircraft, some dropping phosphorus smoke-bombs and others laying smoke curtains with S.C.I. [Smoke Curtain Installation];

(iv) by 2-inch and 3-inch mortars.

(d) It is considered that attention should be drawn to the following points which indicate the periods during which smoke will probably be especially required and to certain qualifica­tions which should be borne in mind:

(i) If the assault is carried out in daylight it is virtually certain that smoke will be required to cover the landing craft during the final stages of the approach. Similarly, if ships or craft are required to lie comparatively close to the shore during daylight hours, then they will require smoke to cover them from shore batteries and from air attack. Such screens may have to persist throughout the daylight hours. A long period of this kind entails the carriage and employment of very large quantities of smoke equipment which may require special provision.

(ii) The withdrawal from a combined operation, especially if the enemy is in close contact and can still bring fire to bear from fixed or mobile batteries, is bound to be a difficult undertaking and constitutes a phase of the operation during which smoke will without doubt play a big part. Experiences at Dieppe more than proved its value at a critical time of this sort.

(iii) The smoke laid to cover craft as they approach the landing places must follow and not precede action by fighter aircraft against these landing places, and the preliminary Naval bombardment.

(iv) A screen of smoke lying between the Headquarters ship and the shore makes visual signalling impossible and signalling by pyrotechnics a doubtful means of inter­ communication. If such conditions are likely to continue for any length of time, then it becomes all the more important to ensure that alternative wireless channels exist in order to replace any that may become for one reason or another, unworkable.

(v) The blanketing of a battery by smoke just prior to an assault upon it is obviously possible and more often than not desirable, but the blanketing of a battery by smoke in order to prevent it shooting is very likely to prove disappointing. 

The former is an offensive use of smoke and is followed by immediate action at close quarters as in the case of the Varengeville battery. 

The latter is a defensive use of the weapon and though it may reduce the battery’s effort by making the local conditions unpleasant and inconvenient it is unlikely to prevent it shooting as the remote observation post which usually exists, will not necessarily have been effected.

(vi) Various actions at Dieppe showed the value of smoke to infantry. When a definite target, such as a defensive position or pill-box or battery is the objective, it can be studied in precise detail from air photographs and the attack on it rehearsed under varying atmospheric conditions over ground which is similar.

(vii) The smoke plan, like the plan as a whole, should be flexible so that the arrangements can be accommodated to fit a change in the weather. Such flexibility will probably demand the provision and carriage of additional smoke stores so that a task which would have been undertaken by aircraft under certain conditions can, if necessary, be undertaken by another method. It took approximately two hours to change a squadron from smoke-curtain installation to smoke-bombs or vice versa. Thus if it is uncertain whether smoke-bombs or S.C.I. will be used, it will be necessary to have some aircraft loaded with S.C.I. and some with smoke-bombs. This may be uneconomical in aircraft, but in order that the flexibility of the smoke plan may be retained the extra aircraft will be necessary. 

Steps are now being taken with the object of discovering how far it is possible to reduce the time taken to load S.C.I. 

(viii) Force Commanders will require frequent meteorological reports throughout the operation, and a meteorologist should be attached to their staff.

(ix) The Dieppe operations showed the necessity for a careful assessment during the planning stage of smoke requirements. These proved higher than were anticipated and there is evidence to show that a greater quantity, particularly of smoke­ grenades, should have been carried. 

375. Provision of Some Form of Light Artillery

(a) Once an assault has got across the landing place and is making progress inland, one of the main and urgent requirements will be adequate supporting fire so that momentum should not be lost and so that strongly defended areas can be assaulted without delay. 

(b) It is considered that such support can only be provided rapidly by self-propelled artillery and by weapons which can be manhandled ashore because beach roadways will not have been laid and proper clearance of obstacles will still be uncompleted. In such conditions equipment which is in any way cumbersome will not fulfil the requirements. 

(c) In these circumstances it is suggested that the allocation of 3-7-in. howitzers and heavy mortars to assaulting units should be considered. 

Note: Save for this note, the entirety of this post is a verbatim copy of a section of a document published in September of 1942. The “block quote” feature (brown line in the left margin) serves simply as a means of indenting the paragraphs that begin with lower case Roman numerals. The report ends, somewhat abruptly, with the paragraphs dealing with light artillery. There is no conclusion.

Source: Combined Operations Headquarters, The Raid on Dieppe: Lessons Learnt, September 1942