Foreign Relations of the United States, The Conferences at Washington, 1941–1942, and Casablanca, 1943

J. C. S. Files

Report by the British Joint Planning Staff¹

secret
C.C.S. 167

[Casablanca,] January 22, 1943.

Continental Operations in 1943

1. In view of the recommendations approved by the Combined Chiefs of Staff in C.C.S. 155/1,² for the “Conduct of the War in 1943,” we examine below the possibilities of cross-channel operations in 1943.

Object of Operations:

2. The objects of cross-channel operations in 1943 may be set down as:

(a) Raids with the primary object of provoking a major air battle and causing the enemy loss.

(b) Operations with the object of seizing and holding a bridgehead and, if the state of German morale and strength of her resources permit, of exploiting success.

(c) Operations on a larger scale to take advantage of German disintegration.

Assumption as to Date:

3. Where figures are quoted, we have assumed a target date of August 1st.

Resources:

4. The number of divisions available will be twelve British, including one airborne, and about four American.

5. Training of naval crews will be the limiting factor in the provision of landing craft for the initial assaults. It is estimated that, without U. S. assistance, the maximum lift which can be provided will be:

Initial assault force:	Two brigade groups, with proportion of armor and commandos.
Total lift including initial assault force:	Two infantry divisions and one armored brigade on light scales, of which two brigade groups and a proportion of armor can be mounted in the initial assault.

Note: This is on the assumption that the British are not required to provide the U.S. with armored landing craft for Mediterranean operations.

6. There will by August 1943 be sufficient air forces, British and American, to support a limited cross-channel operation either against the Pas de Calais or the Cotentin Peninsula, provided operations in the Mediterranean have not drawn too heavily on our Fighter reserves. The decision to carry out such an operation would, however, entail a reorganization of part of the Metropolitan Air Force with a consequent brake on its expansion and operational effort.

Estimated Scale of German Resistance:

7. It may be assumed that the Germans will continue to develop their system of coast defenses, but it is fair to expect that the formations holding these defenses will be of poorer quality than at present.

8. The reserves which the Germans will be able to bring against us must depend entirely on the progress of operations elsewhere in Europe.

In the worst case, if they succeeded without heavy losses in stabilizing their Eastern front on the shortened line of R. Dnieper, and in checking our operations in the Mediterranean, they might rebuild their reserves in Northwest Europe to approximately the level of November 1942, i.e., 41 divisions.

It is possible, however, that they may be forced to make further substantial reductions in the number of their reserve formations in Northwest Europe, and that their capacity to reinforce Northwest France rapidly may be decreased.

9. It is improbable that the strength of the German Air Force on the Western Front will be less than it has been during the last six months, i.e., about 1,000 first line aircraft of all types. In the event of a clear threat of a large-scale landing by our forces in North France or in the Low Countries, the G.A.F. might be prepared to withdraw forces both from the Mediterranean and Russia to increase this strength to 1,500.

Possible Areas for Raids:

10. Raids of which the primary object is to provoke an air battle would best be conducted against the Pas de Calais, but the nature of the defenses would be extremely costly to the assault forces.

Possible Area for a Limited Bridgehead Operation:

11. The Cotentin Peninsula is the only possible objective for offensive operations of which the object is to remain on the Continent, as it is the only area with a short and easily defensible line within reasonable distance of the beaches, and one which, at the same time, permits reasonable air support.

Combined Commanders’ Plan for Assault of the Cotentin Peninsula (Operation Hadrian):

12. In November 1942 the Combined Commanders in London made a detailed study of the problems involved in an assault to seize and hold the Cotentin Peninsula, on the assumption that the Germans could bring up to 15 reserve divisions against the assaulting force during the first fourteen days. They concluded that the minimum requirements for success were:

(a) Initial assault to be made by 5 brigade groups.

(b) Assault to be supported by 10 parachute battalions and an airborne division, less one parachute brigade, for lifting which 847 transport aircraft would be required.

(c) The total force, including assault forces, to be approximately 8 divisions.

(d) The build-up of fighting troops to be substantially complete by evening of D + 1.

General Eisenhower did not himself see the plan, but his representatives collaborated in its preparation and fully concurred in the conclusion as to minimum requirements.

Practicability of Operation With Forces Set Out in Paragraph 5:

13. With the resources available in 1943, neither the size of the seaborne and airborne assault forces nor the rate of build up can approach the requirements of the Combined Commanders. It is clear, therefore, that no operation to seize and hold a footing in the Cotentin Peninsula has any prospect of success unless the German reserves have been very greatly reduced. Similar considerations would apply to a limited operation anywhere on the French coast.

14. There is, however, a good prospect that the German reserves will in fact be greatly reduced by August. It will, therefore, be necessary to make a detailed examination to determine:

(a) Whether with the small assault forces available, it is possible successfully to assault the Cotentin Peninsula.

(b) If such an assault is practicable, to what level German reserves in Northwest France must be reduced in order to give our forces a reasonable chance of holding the Peninsula.

15. It can, however, be said at once, without further examination, that:

(a) A minimum of four brigade groups in the initial assault will almost certainly be necessary.

(b) Shortage of seaborne assault troops will make provision of airborne troops the more necessary.

(c) To insure the success of the initial assault against the strong defenses of the French coast, and to reduce casualties among the assaulting troops, maximum allotment of support craft will be necessary.

(d) The limiting factor in the rate of subsequent build-up is availability of vehicle-carrying craft.

Possibility of Exploiting a Limited Operation:

16. In view of the limited capacity of the port of Cherbourg, operations to exploit success must be designed to secure additional port facilities so as to permit the maintenance of larger forces. Such operations might take the form of an advance by a mobile force, supported by seaborne and airborne assaults, either eastwards to capture the Seine ports or southwestwards to secure the Breton ports. In either instance, preliminary operations would be necessary to expand the bridgehead so as to obtain the use of the port of Caen and the group of airfields in that area.

17. The practicability of undertaking such subsequent operations will, however, depend entirely on the state of German morale and on the extent to which they are able to concentrate reserves to oppose our further advance. The rapidity with which such operations can be undertaken will in any case depend on the rate at which we are able to reconstruct the ports and to build up our own forces and reserves. Even if German opposition is negligible, progress will be slow on account of our limited resources in vehicle-carrying craft suitable for landing over beaches.

Operations on a Larger Scale To Take Advantage of German Disintegration:

18. The return to the Continent in the case of German disintegration will be primarily an administrative problem. The Combined Commanders in London should therefore be instructed to make the necessary plans.

Conclusions:

19. (a) Unless the Germans are forced to reduce their reserves and their beach defenses in Northwest Europe substantially, no limited operation to seize and hold a footing in France is practicable with the resources likely to be available in 1943.

(b) A detailed plan for an operation to seize and hold the Cotentin Peninsula should be made on the basis of resources likely to be available.

(c) An examination should be made to determine to what level German reserves in Northwest Europe must sink in order to give such an operation a reasonable chance if success.

(d) Preparations should be made to mount the operation by August 1st, but the decision to put this plan into execution should be deferred until a reasonably firm estimate of the German reserves on that date can be made.

(e) Outline plans should be made for further operations to exploit success in the event of a breakdown in German morale, e.g., to extend the bridgehead to include Caen and subsequently to secure either the North Seine or Breton group of ports.

(f) The Combined Commanders in London should be instructed to draw up plans for a return to the Continent in the case of German disintegration.

(g) U. S. Government will have to provide:

(1) Assault shipping and landing craft, manned by U. S. crews, to carry at least two brigade groups as assault scales.

(2) Such additional parachute battalions and transport aircraft as may be necessary.

(h) All possible steps should be taken to provide:

(1) Support craft for the assault.

(2) The maximum number of improvised craft for carriage of vehicles.

(Signed)

C. E. Lambe
G. M. Stewart
W. Elliot

1. This report was considered by the Combined Chiefs of Staff at their meeting on the afternoon of January 22, 1943; see ante, p. 688.
2. Ante, p. 774.