1 August, 1941
INTRODUCTION
Object
1. The object of this appreciation is to determine what military forces are the minimum necessary for the defence of this country by 1st April 1942.
SCALE OF ATTACK
Seaborne Invasion
2. There are ample troops available to carry out invasion. The limiting factors are shipping, and the number of craft which can issue from the suitable ports at one time. The J.I.C.in their paper (41) 302 of July 1941 suggest that the scale of attack might be as follows:
(a) A “first wave” of 3 armoured and 4 infantry divisions, carried in light craft, and some merchant vessels converted for running ashore and landing direct on to the beach.
(b) The above to be followed as quickly as possible by a further 2 armoured and 3 infantry divisions, in light craft.
(c) A “main body” of 4 armoured and 16 infantry divisions, carried in merchant vessels, to arrive as soon as arrangements had been made for their reception.
3. This gives a total threat of 9 armoured and 23 infantry divisions, to which must be added some 11 infantry divisions for use as diversions. Any diversion to EIRE is likely to include a proportion of tanks.
Airborne Invasion
4. The J.I.C. estimate that airborne descents might amount to 55,000 troops and equipment. Some 3,600 airborne troops might descend on LONDON by night.
Conclusion
5. Since 27th November, 1940, the estimated scale of enemy attack has increased by 3 armoured divisions and 4 airborne divisions. There has been a decrease of 8 infantry divisions.
INFLUENCE OF OTHER ARMS
6. Interdependence of Services. The defence of the United Kingdom against invasion is a combined operation on a large scale. No one service can prevent the GERMANS landing. The requirements of the Anny in this country were, up to the autumn of 1940; based upon two assumptions:
(a) that sufficient naval forces are retained in home waters to afford a good prospect of intercepting a hostile expedition on passage; and to ensure that, outside the narrow waters at least, the enemy is unable to maintain by sea any forces he succeeds in landing; and
(b) that the Royal Air Force is strong enough to render untenable any landing outside the limit of enemy fighter cover, and precarious within that limit.
It is necessary to examine whether these assumptions are still sound.
Royal Navy
7. In the summer and early autumn of 1940, 30 to 40 destroyers were based at ports in East and South ENGLAND as an Anti-Invasion Striking Force.
8. The necessity to provide as many destroyers as possible to escort Ocean convoys has forced the Admiralty to reduce drastically the Anti-Invasion Striking Force. The number of cruisers required to cover convoys to the MIDDLE EAST and elsewhere has led to a reduction in the available cruiser strength of the Home Fleet. The Admiralty have therefore stated that it may now be as much as 5 to 7 days after the invasion has started before the Navy in home waters can be fully deployed in an anti-invasion role against the GERMAN lines of sea communication with this country.
9. With modern armoured forces, 5 to 7 days is a long time, within which it would be perfectly possible to lose this country and the War, unless the Army is of sufficient strength to deal with the enemy armoured formations. Armoured forces are the best answer to armoured attack. A high scale of armoured formations in this country is therefore now essential.
Royal Air Force
10. The Air Staff believe that until GERMANY can defeat our fighter forces and gain air supremacy, invasion by sea or air is not a practical operation because:
(a) In order to sustain a major invasion, GERMANY must maintain sea communications between the Continent and this country.
(b) With BRITISH predominance at sea this would not have been possible before the rise of air power.
(c) GERMANY must rely upon her fighter and bomber forces to secure her lines of communication by clearing the air of our fighter forces and thus enable her bombers to operate freely against our naval forces.
Consequently, until GERMANY has defeated our fighter force, invasion by sea or air is impracticable.
11. The Air Staff are undoubtedly correct in stating that the struggle for air supremacy will affect the whole course of invasion, but the defeat of our fighter force is not necessary before GERMANY can land troops in this country. Insufficient consideration seems to have been given to the following factors:
(a) Approach under cover of darkness, fog or smoke.
(b) Except in narrow waters, it is doubtful whether the enemy would rely upon securing sea communications for more than a short period, and he might not rely upon capturing a port.
(c) The period of 5 to 7 days during which our naval opposition will not be fully available.
(d) The degree of risk which the enemy will be prepared to accept. The longer the war the more will this increase.
12. Neither side seems likely to gain such a degree of air superiority that on the one hand invasion would be a comparatively simple operation, or on the other that it would be virtually impossible. It would be dangerous to make any other assumption. 13. Our fighter force will be engaged upon:
(a) Meeting the attack on its own organization.
(b) Taking toll of airborne invasion.
(c) Protecting our naval forces.
(d) Providing, within the limits of range, cover for our bombers.
14. Interference with seaborne invasion will therefore depend upon our bombers being able to deal in turn with:
(a) The ports of embarkation.
(b) Craft on passage.
(c) GERMAN troops on our beaches.
15. This ability will be hampered by the following factors:
(a) Enemy fighters. The assembly of the GERMAN force will be given the maximum fighter cover, and, while our fighter force is engaged in protecting its own organization from GERMAN bombers, our bombers will have to face heavy opposition from GERMAN fighters.
(b) The enemy’s possession of the Seaboard from NORWAY to BREST including the BALTIC, will enable him to assemble his invasion force outside the limits of our main bomber effort.
(c) The effort of any bomber force has limitations, and the task of disorganizing and disintegrating a force of some 40 divisions before it sails must be accepted as beyond the power of our bomber force.
This also applies to the craft on passage or enemy landed on our beaches by which time the bomber forces will have suffered losses and be operating at reduced efficiency.
16. The withdrawals from DUNKIRK, GREECE and CRETE were undertaken with a varying degree of fighter cover in the face of heavy bombing, and must lead to the conclusion that the Royal Air Force could not prevent a large GERMAN force being landed in this country. Every replacement of merchant shipping by T.L.C. capacity will assist the GERMANS in avoiding the effects of air bombardment.
Conclusion
17. Thus, while taking into account the casualties which may be inflicted by the Royal Navy and Royal Air Force, the Army must be strong enough to deliver a decisive blow against the maximum enemy force which can be transported to this country.
PROBABLE NATURE OF ATTACK
18. Enemy alternatives. It is open to the enemy:
(a) To launch an airborne invasion. This is improbable, since it could not by itself be decisive, or supplied for any length of time unless followed up by a seaborne invasion. Airborne attack is therefore only likely as a subsidiary to seaborne attack.
(b) To attack by sea in foggy weather, without preliminary air action, with the intention of fighting out the air battle subsequently. Attack in these circumstances demands most exact timing, and will deny to the enemy the extensive air reconnaissance and air support which have so far been a feature of all his assaults. This is therefore a possible, though not a probable alternative.
(c) Preliminary air action directed at obtaining temporary air superiority, followed by seaborne and airborne attack.
(d) To invade by sea and air in fine weather, without preliminary air action, relying on surprise, speed and mass of T.L.Cs. and light craft.
19. If the invasion threatened last autumn be excepted, Germany has never yet in her many campaigns disclosed the imminence of attack by preliminary air bombardment, nor are the Germans likely to repeat the air campaign of last autumn. Further, it must be known to the Germans that there is of necessity a time lag of some days before the weight of our naval power can become effective in Home Waters. The Germans cannot afford to waste one hour of that time.
That the enemy will act in two phases, first an attack to gain temporary air superiority, and second an air and seaborne invasion, is a less probable assumption than that these two phases will follow each other so closely as to merge into one concentrated attack, using every resource of land, sea and air to secure a quick issue by surprise, speed and sheer weight of attack. Of courses (c) and (d), (d) is therefore considered the more probable.
Seaborne Invasion
20. The main features of seaborne invasion are likely to be:
(a) A main attack between the WASH and WEYMOUTH. The need for a quick sea passage, a short maintenance route, and adequate fighter cover, make it unlikely that the main effort will come North or West of the above places respectively.
(b) Diversions aimed at ICELAND (c) and EIRE, and at points on the SCOTTISH Coast and in N.E. and S.W. ENGLAND.
(c) In the main effort, we must prepare for 60/70 ton tanks landed from T.L.Cs. each capable of carrying 4/5 tanks, and with a speed of 10 – 15 knots.
Airborne Attack
21. As invasion becomes imminent, there will be a change in the character of the enemy’s bombing. It is at present employed against civilian morale and on blockade. As invasion approaches, heavy bombing is to be expected on:
(a) Our fighter organization.
(b) Ports on which Fleet counter-action effort will be based; and
(c) Headquarters, roads, railways and communications, with the object of hindering the movement of reserves.
22. The airborne effort, which may be composed of parachutists, glider troops, or troops in troop carrying aircraft, may be employed in four directions:
(a) A concentrated attack on Fighter Command and its associated R.D.F. stations. If successful, this would have the effect of allowing the enemy’s air attack to develop unhindered, and would largely cripple our own air counter offensive.
(b) In the rear of beach defences. To assist the seaborne attack. This must be met by all round defence and mobile local reserves.
(c) On the main approaches for reserves. These may be on the main approaches to the beaches with the object of stopping the arrival of reserves, upon which the success of the battle may depend.
(d) On LONDON itself. The GERMANS might attempt to put down a small force by night with the object of putting out of action Government offices and centres of communication.
Of the above, (a) and (b) constitute the greatest threats. It is not possible to state which is the more likely, as this must depend on the enemy plan. It is probable that there will be a combination of the two, with descents on the most important aerodromes as well as behind the beaches near the vital bridgeheads. Less important aerodromes are likely to be dealt with by air bombardment.
DEDUCTIONS
Main deductions
23. Consideration of the probable scale of attack, of the influence which will be exercised by the other Services, and of the probable nature of attack, makes it possible to draw certain main deductions as to how the defence of this country must be organized.
24. The enemy may attack anywhere between SHETLAND and LANDS END. The resources at the disposal of this country are limited, and it is impossible to think of holding so wide a front in strength. Equally, the number of suitable objectives in the shape of fighter aerodromes, R.D.F. stations, road defiles, etc. for airborne attack, make it impossible to be strong everywhere. It follows, therefore, that there must in this country be a minimum of troops on the coast to deal with seaborne attack, and a minimum inland to deal with airborne attack. Behind these there must be sufficient reserves capable of a rapid counter-offensive against both infantry and armoured formations. It follows that these reserves must include an adequate proportion of armoured formations, and must in all cases be 100% mobile.
Detailed deductions
25. It is also possible to draw certain detailed deductions: Troops on the coast
(a) The likelihood that the main enemy attacks will arise between the WASH and WEYMOUTH demands that the outpost lines in Eastern and South-Eastern Commands, and in that part of Southern Command which lies EAST of WEYMOUTH, must be in greater strength than elsewhere.
(b) The increase in the period before relief to 5 to 7 days, coupled with the increased threat from armoured forces, which the enemy will attempt to land early, demands that the outpost line have at its disposal infantry tanks for immediate counter attack.
Troops inland
(c) The probability of concentrated attack both by bombing and by airborne troops on Fighter Command and its associated R.D.F. stations demands that special protection should be afforded to those aerodromes and their satellites which are considered essential for Fighter Command to continue in the air, and so afford protection to all the others.
(d) The increased airborne threat to Eastern, South Eastern and Southern Commands demands special measures for covering such places as the approaches through the FENS, and through the SOUTH DOWNS, and SALISBUY PLAIN. For such purposes light tanks or carriers are required.
Counter-attack troops on the coast
(e) Behind the troops on the coast must be disposed Corps and Army Reserves containing, a sufficient armoured element to deal with a possible armoured threat in the area, and sufficient infantry to provide support for our tanks and to deal with airborne descents in rear of the beaches.
Counter-attack troops inland
(f) The size of tanks that can be landed by aircraft is limited, and consequently the main threat inland is confined to airborne descents or landings and to certain Commands. For this purpose, infantry are required.
G.H.Q. Reserves
(g) Behind the Corps and Army Reserves, the following will be required as G.H.Q. strategic reserves:
(i) A high proportion of armoured divisions.
(ii) A low proportion of infantry divisions.
(iii) Parachutists with which to assist the counter-attack on such places as the ISLE OF WIGHT or THANET.
Before proceeding to examine the requirements of each Command in turn, it is desirable to apply the above conclusions to the present situation in order to decide whether the present degree of protection can be reduced or should be increased and whether the present organization is suitable.
APPLICATION OF THESE DEDUCTIONS TO PRESENT SITUATION
Troops on the coast
26. A cross-section has been taken of representative parts of the coastline in order to decide whether the present degree of protection can be reduced or should be increased. The cross-sections selected are:
(a) The mainland of SCOTLAND.
(b) The coast between NORTH BERWICK and ALNWICK.
(c) The coast between incl. RYE and excl. PORTSMOUTH.
(d) The coast between excl. EXMOUTH Westabout to incl. LYNTON.
The results of a detailed examination of these cross-sections may be summarised briefly as follows:
(a) That on SCOTLAND there is a gap in the defence line on the coast extending from DUNBAR to BERWICK-ON-TWEED, which in view of a possible German attempt to separate ENGLAND and SCOTLAND is undesirable.
(b) That the coast between RYE and PORTSMOUTH is held by two divisions each with three brigades up, the average frontages held being:
| brigades | 14 miles |
| battalions | 5½ miles |
| companies | 2¼ miles |
(c) That the whole coastline between EXMOUTH and LYNTON is held by one county division, the average frontages held being:
| brigades | 121 miles |
| battalions | 33 miles |
| companies | 11 miles |
27. Examination of the frontages held makes it apparent that no reduction in the number of infantry divisions and brigades required to hold the coastline can be contemplated, unless they are to become merely watchmen. On the other hand, the increased period before relief, and increased armoured threat, demand that this crust should be stiffened by the provision of additional army tank brigades.
28. As regards organization, there is no particular reason why the protection of the coast should not be wholly undertaken by county divisions. It is, however, essential that divisions in the KENT and SUSSEX salient should have a higher proportion of supporting arms. This is the main reason for placing field army divisions on the coast.
Troops Inland
29. The existing scale of aerodrome defence allows for garrisons of varying size, from one platoon to a company. These garrisons are, wherever possible, supported by arrangements for a relief column equivalent to one infantry battalion and a counter-attack force equivalent to one brigade, to be available within one hour and two or three hours respectively.
In addition, it has lately been considered necessary to station light tank or Beaverette troops at a number of aerodromes, and in addition to detach and station within one mile of some 36 essential fighter aerodromes a complete infantry battalion or its equivalent.
These arrangements have only been possible owing to the number of infantry formations at present available, and even then it has been necessary to employ battalions of infantry or squadrons of tanks from formations in G.H.Q. Army and Corps Reserve.
30. It follows, therefore, that any reduction in the number of infantry formations available in the interior of the country will create a situation in which it will be necessary to have a number of independent battalions, sufficient to take on this task in the face of the increased airborne threat to the Commands in question. This may only be possible at the expense of aerodrome garrisons in other Commands.
Counter-Attack Troops for the Coast
31. The enemy may elect to employ the full weight of his armoured strength against, in order of priority,
Eastern and South Eastern Commands
Southern and Northern Commands.
To meet this threat it is necessary to dispose armoured formations for immediate counter-attack in these Commands as there will not be time to move them from one Command to another.
This measure of dispersion in defence which is forced upon us makes it essential that our armoured strength shall be greater than that which the enemy can employ against us.
Additional army tank brigades will, therefore, be required for this role.
Counter-attack Troops Inland
32. The increased threat of airborne attack in Eastern, South-Eastern and Southern Commands now demands special measures. It is possible that the Germans may employ eight airborne divisions in this area.
33. The defence against this form of attack at present relies upon mobile columns organized from area troops, and upon the cover which the presence of mobile armoured and infantry divisions in the interior of the country automatically gives. It follows, therefore, that sufficient of these formations must be available in the vulnerable Commands to counter this threat.
34. Under the present dispositions there are five armoured and seventeen infantry divisions disposed as Corps, Army and G.H.Q. reserves. Under F.F.C.36 there will be eight armoured but only twelve infantry divisions of which four must be stationed on the coast, leaving only eight for disposal in reserve. This reduction from a total of twenty two armoured divisions to a total of sixteen is likely, on examination of the situation by Commands, to prove too great.
G.H.Q. Reserves
35. These at present consist of armoured and infantry divisions in approximately equal proportions. They must be sufficient in number, to turn the scale against any superiority in numbers which the Germans may mount against any particular Command. Armoured formations are most suitable for this purpose and a reduction in infantry can therefore be accepted in G.H.Q. reserve.
EXAMINATION OF REQUIREMENTS BY COMMANDS
Possible Scale of Attack in Each Command
36. Detailed notes on each Command are attached as Appendices ‘F’ to ‘M’.
37. The probable scales of attack on the main Commands may be summarised as shown in the following table:
SCOTTISH COMMAND
| Anticipated Scale of Attack Up To: | 2 seaborne divisions; small airborne parties |
| Points of Departure for Enemy Seaborne Forces: | Bergen, Stavanger |
| Method: | Fast convoy |
| Length of Passage: | 280 miles |
| Time of Transit (Approx.) | 20 hours |
NORTHERN COMMAND
| Anticipated Scale of Attack Up To: | 3 seaborne divisions; 1 airborne regiment |
| Points of Departure for Enemy Seaborne Forces: | Cuxhaven, Wilhelmshaven or Norwegian ports |
| Method: | Fast convoy |
| Length of Passage: | 300-350 miles |
| Time of Transit (Approx.) | 24 hours |
EASTERN COMMAND
| Anticipated Scale of Attack Up To: | 3 armoured divisions; 9 infantry divisions; 8 airborne divisions |
| Points of Departure for Enemy Seaborne Forces: | Scheldt, Ostend |
| Method: | Fast convoy and barges |
| Length of Passage: | 100 miles |
| Time of Transit (Approx.) | 7-14 hours barges, 4-7 hours fast convoy |
SOUTH-EASTERN COMMAND
| Anticipated Scale of Attack Up To: | 4 armoured divisions; 11 infantry divisions; 8 airborne divisions |
| Points of Departure for Enemy Seaborne Forces: | Calais, Boulogne |
| Method: | Fast convoy and barges |
| Length of Passage: | 20-50 miles |
| Time of Transit (Approx.) | 3-6 hours barges, 1-4 hours fast convoy |
SOUTHERN COMMAND
| Anticipated Scale of Attack EAST OF WEYMOUTH: | 2 armoured divisions; 3 infantry divisions; 8 airborne divisions |
| Anticipated Scale of Attack WEST OF WEYMOUTH: | 2 seaborne divisions; small airborne parties |
| Points of Departure for Enemy Seaborne Forces: | Havre, Cherbourg, St. Malo, Brest |
| Method: | Fast convoy and barges |
| Length of Passage: | 70-120 miles |
| Time of Transit (Approx.) | 10-16 hours barges, 5-8 hours fast convoy |
38-40. Analysis of Army Scales.
Summary of Minimum Additional Requirements
41. The additional requirements of each Command are given in Appendices ‘F’ to ‘M’.
42. They may be summarised as follows:
(a) Organization of 108 county battalions into 12 county divisions of 3 brigades of 3 battalions, as opposed to 9 county divisions of 3 brigades of 4 battalions. This number of formations, which will be allotted to Northern, Eastern and Southern Commands, is considered to be the minimum necessary for the control of the long length of coastline in those Commands.
(b) An additional 4 army tank brigades are required over and above the 6 now allowed for.
(c) London District require 3 independent infantry brigades and
10 holding or training battalions. If these are provided, it will release the 1 full scale infantry division which would otherwise have to be allotted.
(d) Scottish Command require an additional independent infantry brigade for the defence of CAITHNESS. In addition, 6 independent infantry battalions are required for OSDEF. (e) Northern Command require 1 full scale infantry division in place of 1 independent infantry brigade group now allotted. If this were done, the 1 independent infantry brigade group already allotted could be released.
(f) Western Command require troops for both NORTH WALES and SOUTH WALES. The release of 1 independent brigade group from Northern Command will provide this brigade group for SOUTH WALES. 1 additional battalion is required for the ISLE OF MAN.
(g) The situation of Eastern Command can otherwise be accepted. See (a) above.
(h) South-Eastern Command require the 2 independent brigades which at present form the garrisons of DOVER and FOLKESTONE for the defence of this most vulnerable area. These 2 extra independent infantry brigades are therefore required.
(i) Southern Command require 1 independent infantry battalion for the SCILLY ISLES.
G.H.Q. REQUIREMENTS
Types of Requirements
44. In addition to the needs of individual Commands, there are the following G.H.Q. requirements:
(a) Aerodromes – calculated to include construction programme up to end of 1942.
| As garrisons | 118 Battalions |
| As independent battalions | 24 Battalions |
| As Light Tank troops | 38 Troops |
Details are given below.
(b) V.Ps. – The total estimated military requirements for protection of V.Ps. calculated with reference to the end of 1942, are: 25 Battalions Home Defence Troops; C.M.P.(V.P.) 12,000 men. Details are given below. (c) Coast Artillery – The total number of men required up to 1 April 1942 is 43,224, of which 38,110 are now available. Details are given below.
(d) Reserves – No additional G.H.Q. reserves are required beyond those allowed for … namely 1 full scale and 4 armoured divisions, except that 1 airborne brigade is required to assist counter-attacks against such objectives as the ISLE OF WIGHT, the SCILLY ISLES or the ISLE OF THANET.
(e) Home Guard – As the number of infantry formations is reduced, the Home Guard will become an increasingly essential adjunct to the Field Army. Their role is the breaking up of local airborne attack, and also of seaborne attack by the defence of nodal points. In addition, on the coast they can assist by reinforcing the troops already there. Now that their training is advancing they must be asked to provide from their younger men more mobile detachments using bicycles, motor-cycles and motorcars, with which they would be able to get quickly about inland to deal with airborne attack.
(f) 1st reinforcements – It is to be assumed that, in the event of invasion, all formations will be engaged simultaneously, and will be called on to fight a series of major actions within a fortnight or three weeks. Heavy casualties must be expected, especially in the opening action; it will be essential that reinforcements are available to bring formations up to fighting strength. The following is therefore considered the minimum:
| R.A.C. | 15% |
| R.A. | 7.5% |
| R.E. | 5% |
| Signals | 5% |
| Infantry | 15% |
with a slightly higher proportion of officers in each case.
CONCLUSION
Total Revised Minimum Requirement
45. The minimum requirements of this country are therefore:
1 Airborne brigade.
OSDEF (6 independent battalions).
5 independent infantry brigades.
3 independent infantry brigade groups.
12 county divisions of 3 brigades of 3 battalions.
14 full scale divisions.
8 armoured divisions.
10 army tank brigades.
188 battalions (Young Soldier or Home Defence) as aerodrome garrisons.
300 light tank troops as aerodrome garrisons.
24 independent battalions as external protection to essential fighter aerodromes.
2 independent battalions for the ISLE OF MAN and SCILLY ISLES.
11 holding or training battalions for London District.
25 battalions of Home Defence Troops for V.Ps.
12,000 C.M.P.(V.P.) for V.Ps.
43,224 men to man coast artillery batteries.
A greater measure of mobility for the Home Guard.
1st reinforcements on the scale of:
| R.A.C. | 15% |
| R.A. | 7.5% |
| R.E. | 5% |
| Signals | 5% |
| Infantry | 15% |
with a slightly higher proportion of officers in each case.
SCOTTISH COMMAND
General
1. An enemy seaborne expedition against Scotland would for geographical reasons probably be launched either from Norway (BERGEN and STAVANGER) or via the Skagerrak from German Baltic ports. Owing in the one case to the broken nature of the Norwegian coast, in the other to distance, we could not be sure of obtaining warning of the preparation of an expedition.
2. The distance from BERGEN to KINNAIRDS HEAD is 280 miles; from the western exit of the Skagerrak somewhat longer. For a small force the enemy might use a 16 – 18 knot convoy capable of completing the passage in 16 – 20 hours. During the winter much, if not all, of this passage could be accomplished in darkness, and it would be unwise to rely on any but the briefest warning of attack. On the other hand the hours of light in summer much reduce the likelihood of seaborne attack in these latitudes, and greater risks would be justifiable.
3. Similarly an enemy airborne attack, based on Norwegian or on the main continental aerodromes, could be launched without warning. Possible enemy objectives
4. The order of importance of the more likely objectives is thought to be:
| (a) SCAPA FLOW (Y 92) | Naval base. |
| (b) CAITHNESS | For operation against SCAPA FLOW. |
| (c) FIRTH OF FORTH | Fleet anchorage, Naval and R.A.F. installations, port of Leith, and gateway to (d). |
| (d) GLASGOW – CLYDE | Industrial and shipping area. |
| (e) INVERGORDON (J 29) | Fleet anchorage. |
| (f) Coast of MORAY and BANFF | As a base for air operations. |
| (g) ABERDEEN | For diversionary purposes. |
5. As regards these objectives the reinforcement for the ORKNEYS or SHETLANDS is dependent upon the availability of a seaborne reserve in the CLYDE which can be moved in good time to SCAPA. It is assumed that this force will now always be maintained.
6. The county of CAITHNESS is extremely isolated and requires a permanent garrison. An additional Infantry Brigade is therefore required.
7. The loss of the GLASGOW – CLYDE area would in time probably be decisive. Its defence and that of the FIRTH OF FORTH which leads directly to it are therefore of first importance. They are virtually a single problem. The Polish Forces provide a minimum defence for the north of the FORTH. A gap, however, exists south of the FORTH which cannot be covered except by the provision of one Field Army Division in reserve.
8. The defence of INVERGORDON and the Coast of MORAY and BANFF must be self-contained, since poor communications will prevent any rapid reinforcement from southern Scotland. One full scale Field Army Division is required.
9. ABERDEEN is of little real importance.
10. Finally it is possible that the enemy might make use of the good road exits S.W. from BERWICK to direct forces landed on the inter-Command boundary against CARLISLE with the ultimate aim of isolating SCOTLAND from ENGLAND.
Likelihood and Scale of Enemy Attack
11. The threat of seaborne attack must be rated as small for the following reasons:
(a) Lack of an objective such as London, the capture of which might be decisive quickly;
(b) relatively long sea voyage through very dangerous waters, making subsequent maintenance, if not the original passage, of an expedition most hazardous; and
(c) difficulty of providing fighter cover.
The threat of airborne attack must be rated as very small. The main continental aerodromes are far distant; Norwegian aerodromes are limited in number. From neither could any sustained fighter cover be given.
In this connection it is understood that the enemy could not, by airborne invasion alone, use Scottish aerodromes as bases for attacking the fleet at Scapa Flow; since he could not, at the distance, supply his aircraft in Scotland in the face of opposition. Any such attack would, therefore, either have to be launched from Norwegian aerodromes or the enemy would have to keep open a line of communication by sea to Scotland.
12. The most that is to be expected therefore is a raid, probably for diversionary purposes and not exceeding up to 2 seaborne divisions, and small airborne parties.
Even if the enemy succeeded in putting such forces ashore, his effort could only be of short duration since he would have the greatest difficulty in maintaining them. It is on this basis that defence requirements must be estimated.
Total Requirements
O.S.D.E.F. (incl. 6 independent battalions)
Polish Forces
2 full scale divisions
1 independent infantry brigade
NORTHERN COMMAND
General
1. An enemy seaborne expedition against Northern Command might be launched from the Low Countries, in which case the actual passage (Scheldt – Humber about 200 miles) could be completed at night during the winter months. It is far more likely, however, that the enemy would decide to launch his main attack on south-eastern England, for which purpose he would need Dutch, Belgian and French harbours, and that only a diversionary raid would be launched against Northern England from the Elbe or via the Skagerrak from Baltic ports. In this event the sailing of the northern convoys might well he observed in fair weather, although it would be unsafe to rely on any but the briefest warning of attack.
2. A seaborne expedition against Northern Command would suffer from much the same disadvantages as an expedition against Scotland,
i.e. –
(a) Relatively long sea passage, not lending itself to the use of barges and specialised small craft.
(b) Eventual serious interference from the Royal Navy, at least as far south as the Humber.
3. Enemy airborne attack based on the main continental aerodromes could be launched with little warning. At present such an attack would suffer from the inability of most of the enemy’s fighter aircraft to cover the operation. It would also be difficult for the enemy to nourish an airborne expedition in this part of England.
Possible Enemy Objectives
4. In order of importance these are:
(a) The HUMBER leading directly to the LEEDS – BRADFORD industrial area.
(b) The TYNE.
(c) The TEES, leading directly to MIDDLESBROUGH – DARLINGTON and a possible route for a flank attack on the LEEDS area.
The loss of the main industrial area of the Midlands, i.e. LEEDS – BRADFORD – MANCHESTER would in time be decisive; the nearest approach is by the HUMBER, where the coast is generally more suitable for landing than elsewhere. The defence of the Humber area is therefore of first importance.
Likelihood and Scale of Enemy Attack
5. For the reasons given in paras. 3 and 4, nothing more than a large scale raid for diversionary purposes is to be expected. Its scale might be up to 3 seaborne divisions [and] 1 regiment of airborne troops
6 and 7. Allotment.
8. The long coast line and corps organization of Northern Command make it essential that instead of 3 county divisions of 3 brigades of 4 battalions, it be allotted 4 county divisions of 3 brigades of 3 battalions with the corresponding increase in supporting arms which this will imply. 1 additional army tank brigade is also required.
9. The reserves available are too small in proportion to the length of frontage held and the possible scale of attack. 1 additional full scale infantry division is required, instead of the 1 brigade group.
Minimum Requirements
10. 4 county divisions of 36 battalions
1 armoured division
1 full scale division
2 army tank brigades
EASTERN COMMAND
General
1. The salient factors which affect the defence of Eastern Command are:
(a) the wide range of ports available to the enemy for the preparation and launching of a seaborne expedition; these include German Baltic ports, and ports of the Low Countries,
(b) the Command lies within effective range of all the enemy’s fighter forces, short range and long range,
(c) the short sea passage favours the use of barges and other specially prepared small craft from which direct landings can be made on beaches,
(d) the narrow seas are the one area in which our naval superiority, particularly in heavy ships, is likely to be least effective and longest delayed.
Enemy Objectives
2. There is only one real objective – LONDON. The capture of LONDON would automatically include the destruction of the organization of A.D.G.B. the loss of which would deprive us of effective fighter protection. The capture of fighter aerodromes and R.D.F. stations would probably be included amongst the enemy’s initial objectives.
Likelihood and Scale of Attack
3. A major attack on this part of England must be regarded as possible at any time and in any season. The most probable plan would be a pincer movement directed on LONDON or to the west of it from East Anglia on the one hand and Kent and Sussex on the other, with defensive flanks thrown out as necessary. The scale of seaborne attack is estimated at: 3 armoured and 9 infantry divisions.
4. As regards airborne attack the enemy could land up to:8 divisions.
5 and 6. Allotment.
7. The Corps organization of Eastern Command would permit of 3 county divisions consisting of 12 battalions, but in the general interest of uniformity 4 divisions of 9 battalions are preferred. The force available can be accepted subject to:
(a) the need explained elsewhere for additional army tank brigades;
(b) the increase in supporting arms which the proposed reorganization of county divisions will imply.
Minimum Requirements
8. These are therefore:
4 county divisions of 36 battalions
2 full scale divisions
1 armoured division
3 army tank brigades
LONDON DISTRICT
General
1. LONDON lies in the area over which the enemy can obtain maximum fighter cover and to which he has the shortest sea passage from the continent. It is, moreover, certain to be the objective of any enemy attack in south east England.
Likelihood and Scale of Enemy Attack
2. The security of LONDON is the essence of the defence problem in Eastern and South Eastern Commands. There are, however, two possibilities, defence against which is the primary responsibility of London District. They are an attempted coup-de-main against the capital by either:
(a) large scale parachutist and airborne attack; and/or
(b) a direct assault by shallow draught craft up the Thames Estuary.
Projects such as these might well appeal to the enemy. Their object would be to paralyse the machinery of government at the very time it was most needed.
3. The number of parachutists who might theoretically be landed has been estimated as about 3,600.
4. So long as our fighter aircraft continued to operate from aerodromes in south east England, however, troop carrying aircraft of all sorts would suffer very heavy casualties by day and it is unlikely that the number of parachutists who could land simultaneously, or within a short period, would be enough to isolate LONDON. A small descent by night might, however, be used in an attempt to disorganize the Government and communications at a critical time. The possibility of gliders being used on the outskirts of LONDON cannot be overlooked.
Resources of LONDON
5. Before estimating the troops required in London District, it may be observed that:
(a) the Thames Estuary is covered by fixed defences and by light naval forces at HARWICH and CHATHAM;
(b) the narrower waters inside the estuary are covered by M.G. defences and armed river craft;
(c) the Home Guard total nearly a quarter of a million men;
(d) the presence of the balloon barrage and of strong A.A. defences provide armed detachments of considerable value.
Internal Security
6. Internal security was always a heavy commitment in the London District in peace, and it was anticipated that the commitment would become heavier in war. In fact, there has up to the present been no demand for troops for internal security, but it is not sound to assume that no such demand will be made. War conditions, with continued bombing and enemy propaganda, may yet lower civilian morale.
There are, however, over 20,000 police in LONDON and several military depots capable of turning out small columns. It is therefore not considered necessary to make specific provision for internal security in addition to the field force recommended below.
Field Force
7. As explained in paragraph 2, the main battle for LONDON must be fought by formations in South Eastern and Eastern Commands. Locally, the entrances to LONDON should be held by Home Guards. What is required of the field forces in the District is ability to deal with surprise incursion and to restore a situation by delivering a counter-attack. For this it is estimated that 1 full scale division or the equivalent is sufficient.
8. Allotment.
Minimum Requirements
9. It is, however, difficult to employ artillery etc. in LONDON, and it is considered that the following could be accepted:
1 brigade group
2 brigades
10 holding or training battalions
exclusive of the requirements of the Royal Household and of the Cabinet.
10. The provision of these would release one full scale division for employment elsewhere, e.g., NORTHERN COMMAND.
SOUTH-EASTERN COMMAND
General
1. The salient factors which affect the defence of South Eastern Command are:
(a) The wide range of ports available to the enemy for the preparation and launching of seaborne attack.
(b) The Command lies within the effective range of all the enemy’s fighter forces – short range and long range.
(c) The short sea passage favours the use of barges and other specially prepared small craft from which direct landings can be made on beaches; a particularly dangerous area in this respect being between the NORTH FORELAND and DUNGENESS. It also rules out the possibility of relying on even short warning that an expedition has sailed.
(d) The narrow seas are the one area in which our naval superiority, particularly in heavy ships, is likely to be ineffective. The enemy can command at least half the beaches of the Channel with the heavy coast artillery which he has mounted. He can well hope to cover the rest of the passage with dive bombers. Here, if anywhere, the German can put down his head and charge like a bull.
(e) The lack of depth between the coast and LONDON, which makes it essential that the enemy should be stopped on or near the beaches. All usable beaches must be held, and held in some strength.
Enemy Objectives
2. There is only one real objective – LONDON, the capture of which would mean the loss of the centralised fighter control. The capture of fighter aerodromes and R.D.F. stations would probably be included amongst the enemy’s initial objectives.
Likelihood of Scale of Attack
3. A major attack on this part of England must be regarded as possible at any time and in any season. The most probable plan would be a pincer movement directed on LONDON, or to the west of it from East Anglia on the one hand and Kent and Sussex on the other, with defensive flanks thrown out as necessary. The scale of seaborne attack is estimated at 4 armoured and 11 infantry divisions.
4. As regards airborne attack, the enemy could land 8 divisions. Airborne landings would be easier to cover in Kent and Sussex than anywhere else in England.
5. Allotment.
6. It is essential that on this part of the coast all usable beaches and ports should be adequately covered. This cannot be done without the 2 additional brigades which are at present located at DOVER and FOLKESTONE.
Minimum Requirements
7. Minimum requirements are therefore:
2 brigades
6 full scale divisions
1 armoured division
3 army tank brigades
SOUTHERN COMMAND
General
1. An enemy seaborne expedition against the Southern Command would probably be launched from northern or north western France. There should be some warning of the preparation of this expedition but, in conditions of poor visibility, it might be launched unobserved. The approximate distance between assembly ports and ports of the south coast are:
| CHERBOURG to ISLE OF WIGHT | 70 miles |
| CHERBOURG to PORTLAND | 75 miles |
| HAVRE to ISLE OF WIGHT | 95 miles |
| ST. MALO to LYME REGIS | 157 miles |
| BREST to PLYMOUTH | 180 miles |
| L’ORIENT to FALMOUTH | 250 miles |
It would, therefore, be possible for 15 knot ships, and in winter probably barges and T.L.Cs. also, to reach ISLE OF WIGHT – LYME REGIS during the hours of darkness from CHERBOURG or HAVRE. Ships from ST. MALO might make the crossing in darkness during the winter, but ships from BREST or L’ORIENT would have to start or complete the crossing in daylight.
2. An airborne attack from aerodromes in northern France could take place with little warning.
Likely Enemy Objectives
3. There appear to be two distinct objects which the enemy might have in view in attacking the Southern Command, and each gives rise to a distinct defence problem:
(a) an attack on the Southern or south-western areas to create a diversion and draw off reserves in that direction;
(b) an attack on the Hampshire area with a view to forming a defensive flank facing west to cover his main operations in Kent and Sussex.
Either is likely to be accompanied by airborne landings in the Salisbury Plain – Berkshire Downs area.
4. or the two it is thought that (b) is the more likely, because the chances of maintaining the expedition by sea would be greater. Moreover, this course would have a more direct influence on the main attack in Kent and Sussex. Any such operation is likely to be accompanied by an attack on the ISLE OF WIGHT. As regards (a) a possible plan would be an attempt to cut off Devon and Cornwall, and the cables to America and the Dominions by seizing the narrow neck of land LYME REGIS – TAUNTON – BRIDGWATER BAY.
Likelihood and Scale of Attack
5. While the launching of the main attack against this part of England does not hold out sufficient prospects of a quick decision to be attractive to the enemy, subsidiary operations must be regarded as probable.
6. Their scale of attack is estimated at up to 2 armoured, 3 infantry and
8 airborne divisions east of WEYMOUTH as a diversion; 2 seaborne divisions and small airborne parties west of WEYMOUTH.
7 and 8. Allotment.
9. Only one Corps Headquarters will be available to Southern Command. In these circumstances it is desirable that county divisional commanders should have a less unwieldy front to handle, which will ease the increased responsibility which they will have to accept, and facilitate the action of reserves. 4 county divisions of 3 brigades of 3 battalions are therefore required. The scale of defence can therefore be accepted, subject to:
(a) the need explained elsewhere for additional army tank brigades;
(b) the increase in supporting arms which the proposed reorganization of the county divisions will imply, and
(c) 1 independent battalion for the SCILLY ISLES.
Minimum Requirements
10. These are therefore:
4 county divisions of 3 brigades of 3 battalions
1 full scale division
1 brigade group
1 armoured division
2 army tank brigades
1 independent battalion.
WESTERN COMMAND
General
1. An enemy seaborne expedition against the Western Command would under present conditions have to be launched from the north-west or west coast of France. We should obtain warning of its approach except perhaps in foggy weather, although we certainly might not have warning of its preparation.
A seaborne expedition would have to run the gauntlet of the minefield between CORNWALL and EIRE, and would be liable to attack by submarines and light craft as well as by aircraft. The initial passage would be hazardous and, it is most improbable that the enemy would be able to maintain any forces he succeeded in landing.
2. It is unlikely that the enemy would attack EIRE as a prelude to the invasion of Western Command. His objects in attacking EIRE would almost certainly be:
(a) to obtain a decision by blockade;
(b) to divert forces from the United Kingdom preparatory to an attack on south eastern England;
Indeed an enemy attack on EIRE would increase the threat to South Eastern and Eastern, rather than to Western Command.
3. Despite the paucity of our fighter defences in the west, and particularly in the narrow neck of land LYME BAY – TAUNTON which forms the direct route for aircraft to Wales, an airborne attack on the Western Command other than for sabotage purposes is unlikely because:
(a) it could only be supported by a seaborne expedition with great difficulty;
(b) most of the Command lies outside the limit of the enemy’s short range fighters.
4. To sum up – the threat to Western Command is at present not great.
The threat from seaborne attack is unlikely to be substantially increased even after a successful enemy occupation of EIRE.
Possible Enemy Objectives
5. These are:
(a) The area MERTHYR-TYDFIL (0 52) – NEWPORT (0 70) – CARDIFF – SWANSEA (0 11)
(b) MANCHESTER – LIVERPOOL – BIRKENHEAD
(c) WOLVERHAMPTON (K 31) – BIRMINGHAM – COVENTRY (d) BARROW-IN-FURNESS (D 69) and ports in the vicinity.
Likelihood and Scale of Enemy Attack
6. For the reasons given in paragraphs 1 – 4 above, the most that need be anticipated is a small seaborne raid of the tip and run type and small airborne raids for purposes of sabotage. As a basis for assessing defence requirements the following appears reasonable:
| Seaborne | 1 to 3 brigades |
| Airborne | 1 or 2 battalions |
7. Allotment.
Minimum Requirements
8. It is only possible to give Western Command one full scale division. The possible internal security problem at the Western Ports and in South Wales, and the geographical features of the Command demand troops in both North and South Wales. In addition the one division may have to be withdrawn from Western Command as G.H.Q. is forced to reconstitute its reserves during battle. One additional infantry brigade group is necessary, together with 1 battalion for the ISLE OF MAN. These are therefore:
1 full scale division;
1 brigade group;
1 independent battalion.
The two first formations are likely to be required as G.H.Q. Reserves as the battle develops.
AERODROMES
1. The requirements of aerodrome defence fall under two heads:
(a) A permanent garrison
(b) External forces equivalent to 1 infantry battalion for vital Fighter aerodromes.
2. In addition to the above, there are on all aerodromes personnel who are normally concerned with the administration and maintenance of the aircraft at the station, but who are available, assuming that they are armed and trained to take their part in the defence of the aerodrome when the battle is joined.
3. Under the present organization, personnel for the permanent garrison (para. 45(a)) are found partly by the Army and partly by the R.A.F. For purposes of calculation it is assumed that all these personnel will in future be found by the Anny.
4. External forces (para. 45(b)) are at present found from Field Force formations in Corps, Army, or G.H.Q. Reserve. In view of the greatly decreased numbers of infantry formations which will, under the new dispositions, be available, it will no longer be possible to find all these battalions from that source. New arrangements will be required, and can only be found by the provision of additional independent battalions.
5. There are at present 459 aerodromes; it is anticipated that by the end of 1942 there will be 755 aerodromes. It is unlikely that this number will ever be greatly increased, as there is a limit to the flat ground available in this country.
In addition, there are now 85 R.D.F. Stations; it is anticipated that there will be 170 by the end of 1942.
Personnel (including R.A.F. ground defence personnel) at present available for the defence of aerodromes and R.D.F. Stations, or already asked for and approved by the Chiefs of Staff, totals 126,800 men, say 127 battalions.
Troops required up to the end of 1942 are:
| (a) As garrisons | 188 battalions |
| (b) As independent battalions | 24 battalions |
| (c) As light tanks or beaverette troops | 300 troops. |
If, however, the R.A.F. retain responsibility for Class ‘C’ aerodromes for finding A.A. L.M.G. personnel on all aerodromes and for finding personnel to man Beaverette Troops, the above figures will be reduced to:
| (a) As garrisons | 118 battalions |
| (b) As independent battalions | 24 battalions |
| (c) As light tank troops | 38 troops. |
V.Ps.
1. The attached table shows the total estimated military requirements for the protection of V.Ps., calculated with reference to the end of 1942. These are:
25 battalions Home Defence troops
C.M.P. (V.P.) 12,000 men.
2. It will only be possible to reduce the Home Defence troops to 25 battalions by providing them with a high scale of mobility.
ESTIMATED V.P. REQUIREMENTS TO END OF 1942
COAST ARTILLERY
1. The requirement for coast artillery personnel up to 1 April 1942 is 43,224, of which 38,110 are now available.
2. The local protection of coast artillery batteries is in many cases insufficient, by reason of the fact that the outpost line on the coast cannot always cover these batteries, and coast artillery war establishments make no provision for personnel for this purpose.
3. Each coast battery in the ORKNEYS and SHETLANDS and from WICK to LANDS END requires such protection. Of these, some are covered by existing defended localities; others are isolated. Overall infantry on the scale of 1 platoon per battery is required.
4. On this basis a total of 18 battalions of static troops would be necessary for affiliation as required to county and field formations on the coast. The need, however, for the utmost economy of troops imposes the necessity of doing without these battalions and accepting the risk.