The “Marshall Memorandum” concerning Operations in Western Europe circa April 1942

Source: Was found reprinted in “CROSS-CHANNEL ATTACK, 1942: THE BRITISH REJECTION OF OPERATION SLEDGEHAMMER AND THE CHERBOURG ALTERNATIVE”, a Thesis by Joseph L. Strange at the University of Maryland in 1984. It in turn references Butler, Grand Strategy, III, Appendix III, pp. 675-681.

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1. Western Europe is favored as the theater in which to stage the first major offensive by the United States and Great Britain. By every applicable basis of comparison, it is definitely superior to any other. In point of time required to produce effective results, its selection will save many months. Through France passes our shortest route to the heart of Germany. In no other area can we attain the overwhelming air superiority vital to successful land attack; while here and here only can the bulk of the British air and ground forces be employed. In this area the United States can concentrate and maintain a larger force than it can in any other. A British-American attack through Western Europe provides the only feasible method for employing the bulk of the combat power of the United States, the United Kingdom and Russia in a concerted effort against a single enemy.

Another, and most significant consideration is the unique opportunity to establish an active sector on this front this summer, through steadily increasing air-operations and by raids or forays all along the coasts. This initial phase will be of some help to Russia and of immediate satisfaction to the public; but what is more important it will make experienced veterans of the air and ground units, and it will offset the tendency toward deterioration in morale which threaten the latter due to prolonged inactivity.

Finally, successful attack through Western Europe will afford the maximum possible support to Russia, whose continued participation in the war is essential to the defeat of Germany.

2. Decision as to the main effort must be made now. This is true even if the invasion cannot be launched during this year. A major attack must be preceded by a long period of intensive preparation. Basic decision is necessary so that all production, special construction, training, troop movements and allocations can be co-ordinated to a single end. Until this process of co-ordinated and intensified effort is initiated, it is difficult to calculate even the approximate date at which a major offensive can be undertaken. Decision now will stop continued dispersion of means.

The element of time is of the utmost importance. Physical limitations both as to the time and strength of the attack are the shortage of shipping and landing-craft. But we must begin a sustained offensive before Russia can be defeated and before Vichy France, Span,, Sweden Portugal and Turkey are drawn into the ranks of the enemy.

3. Our proposal, more fully outlined later, provides for an attack, by combined forces of approximately 5800 combat airplanes and 48 divisions, against Western Europe as soon as the necessary means can be accumulated in England — estimated at 1 April 1943, provided decision is made now and men, material and shipping are conserved for this purpose. (Included preparations for an 'emergency' offensive by fall of 1942 will be explained later.)

The plan contemplates three main phases.

(a) Preparation, involving:

(1) Immediate co-ordination of procurement priorities, allocations of material and movements of troops and equipment.

(2) Establishment of preliminary active front this coming summer--for training, demonstration, deception, and destruction .

(3) Development of preparations for possible launching of an 'emergency' offensive this coming fall.

(b) Cross - Channel movement and seizure of beachheads between Le Havre and Boulogne.

(c) Consolidation and expansion of beachheads and beginning of general advance.

4. A special significance of the preparatory phase is that it presents opportunity for the intensive and specialized training of troops, without which the plan could have meager prospects of success. This special training, beginning with fundamentals of technique in loading and unloading of boats, must advance progressively through logical steps until it comprises constant raiding by small task-forces at selected points along the entire accessible coastline held by the enemy.

The beneficial results to be derived from continuous raiding fall into two main categories. On the one hand there will be obtained a variety of useful information, applying to details of geography, hostile dispositions, tactics and intentions. Some measure of deception as to time and the place of the final attack should result. The continuation of such raids over a long period may lead the enemy to believe that no all-out offensive is to be attempted or, conversely and equally valuable, may induce him to withhold from the Russian front air and ground units because of constant fear that the raids may develop at any moment into a major attack. In this latter event the raiding process would, on a limited scale, serve the same purpose as the opening of a new front on the continent itself.

But by far the greatest benefits to be anticipated from constant-raiding will be the resultant increase in the battle efficiency of the participating troops. After troops have completed normal phases of training and manoeuver, it is essential that, to avoid deterioration, they begin gradual entry into actual battle, preferably under conditions that, so far as possible, will guarantee the small success that raids seek, while minimizing losses in personnel and material. These successes can be assured by careful preparation for each venture, somewhat in the pattern of the trench raid of the First World War. The characteristics of each action will be a sudden concentration of overwhelming air superiority supported by gun-fire where practicable, with speed, surprise and precision in execution. For air forces, technical methods will be different, but the purposes and principles the same. In this way, troops will acquire that morale and self-confidence that only participation in battle can impart. They will perfect technique, methods, and co-ordination not only as among individuals, but also as between commanders, staffs and units. Communications between land, air and sea forces will be developed to a high level of efficiency. Equipment will be tested under combat conditions. Troops will be kept on their toes, mentally alert, and, by these means, gain that feeling of moral ascendancy over the opponent that always characterizes a victory-imbued army. Successfully conducted, these raids will permit our troops to enter upon the final venture with an ability to meet, on equal terms, the battle-trained veterans of the German Army.

Losses in landing-craft, though small in each individual raid, will be considerable in accumulated total. Production plans must foresee and provide for this inescapable requirement, and insure that equipment so lost will not be reflected in a diminished scale of attack when the final offensive is undertaken.

5. An advantage of this plan is that, during the preparatory period, it provides means to act promptly under either of the following eventualities :

(a) If the imminence of Russian collapse requires desperate action, a sacrifice attack could be made immediately.

(b) If German forces are almost completely absorbed on the Russian front, or a deterioration of the German military power is evident, a prompt movement to the Continent could be undertaken.

OUTLINE PLAN FOR INVASION OF WESTERN EUROPE

6. Assumptions

(a) That so far as the United States is concerned the line, Alaska-Hawaii-Samoa-Australia will be held and Pacific garrisons increased from present approximate strength of 175,000 to an approximate strength of 300,000.

(b) That present U.S. commitments in troops and ships will be executed. These include dispatch of the 41st and one additional division to Australia, one division to New Zealand, the loan of sufficient shipping to the British to move 40,000 troops to the Middle East, and the building up of a small air force in China-India. Providing the British furnish the necessary planes from aircraft now allotted to them, two groups pursuit, one group medium bombardment and two groups light bombardment have been promised for the Middle East as the additional U.S. commitment to theaters other than Western Europe. Transfer of these air units will have a corresponding effect in diminishing the early U.S. air-effort in Europe.

(c) That Russia is still effective in the war to the extent that the bulk of the German forces are required on the Russian front.

(d) That Axis forces in Western Europe remain at approximately their present strength.

7. Combat Strength Required

From an examination of the present hostile situation, it is estimated that combat power and readiness as follows is necessary for a successful attack :

(a) Adequate air superiority over the enemy, involving the use by the allies of a minimum of 3,000 fighters and 2,850 combat planes other than fighters (Combined British and U.S.).

(b) Sufficient landing-craft to land in the first wave the major combat elements of an infantry and armored force of at least six divisions. At the beginning of the actual invasion, U.S. land forces in England or en route should approximate 30 divisions. Total U.S. strength in England at that time will approximate 1,000,000 men.

(c) An ability to land on the western coast of Europe behind the leading wave, a weekly increment initially of at least 100,000 troops, and, after the invasion forces have landed, a continuous flow of reinforcements from the United States at the maximum rate that shipping will permit.

(d) Sufficient naval support to assure freedom from interference by hostile surface and sub-surface craft.

8. Execution

(a) The plan provides for the movement to the British Isles of U.S. air and ground forces comprising approximately one million men to participate with the British in an invasion of France between Le Havre and Boulogne. Logistic factors fix the earliest possible date for an attack on this scale at about 1st April, 1943. Bottlenecks, as to time, will be shipping and landing-craft, which will not be available in sufficient quantities by the time that aircraft, ground equipment and ammunition can be supplied.

(b) As previously explained the operation is planned in three phases with actual combat beginning in the preparatory phase.

Immediately after approval of the basic plan, all production and allocation plans must be reviewed and co-ordinated to this objective to meet obvious shortages, particularly in shipping and landing craft.

U.S. air and ground units must begin moving to the United Kingdom by every available ship.

Plans for execution of an 'emergency' operation are to go forward constantly, based always upon the maximum force that could be transported across the Channel at any given moment.

(c) The second and third phases are the cross-Channel movement and beginning of the general advance. The invasion itself will consist of the seizure of beachheads between Le Havre and Boulogne. The main landing is to be made on a six-division front. Parachute and airborne troops will be employed in addition to combat aviation in assisting the ground forces to establish beachheads and to prevent rapid movement of German reinforcements toward the coast. As soon as a beachhead is established, strong armored forces are to be rushed in to break the German resistance along the coast and seize the line of the Oise-St.Quentin. A movement towards Antwerp will then follow to widen the salient and permit the movement of additional forces across the Channel between Boulogne and Antwerp. Short range aircraft will be based on land fields as quickly as they are captured.

9. U.S. and British forces as follows should be in Great Britain or en route when the land attack begins:

U.S. Forces

British Forces

Will be available, as modified by any airplanes sent to Middle East

1,450 Fighter planes.
1,800 Combat planes other than fighters.
400 Transport planes.
18 Infantry Divisions.
6 Armored Divisions.
5 Motorized Divisions.
1 Airborne Division.
11 Parachute Bns.
30 AA Regts.

Numbers of British aircraft shown are minimum requirements. Information is not at hand as to how many the British can make available.

1,550 Fighter planes.
1,000 Combat planes other than fighters.
200 Transport planes.

The British must provide at least the following ground troops :

15 Infantry Divisions.
3 Armoured Divisions.
1 Parachute Brigade.
3 AA Gps.

10. The success of the operation will depend upon the availability of adequate naval forces for its support.

11. General Comments

(a) An attack in Western Europe will have a protective effect on the remainder of the Atlantic area. The garrisons in the Atlantic should not require material reinforcements. This does not apply to the Pacific, to India, and to the Middle East, consequently our protective measures in those regions must be adequate.

(b) U.S. troops will be equipped and trained in time for the operation .

(c) American shipping available for movement overseas of the U.S. troops will transport only about 40 per cent of the number involved by 1st April, 1943, leaving some 600,000 men to be transported by shipping from British and other sources. If this movement must depend entirely on available U.S. Shipping, the date of initiating the invasion of France must be postponed until late summer of 1943, by which time U.S. shipping can effect the overseas movement of the entire force.

(d) The shipping situation is under continuous study. However, it is believed that when the movement of reinforcements to the Middle and Far East now projected for 1942 has been effected, and the situation in those areas stabilized, sufficient U.S. and British passenger transports can be made available for the movement of U.S. troops to England to meet the requirements of this plan. Additional cargo vessels will have to be diverted after 1st January, 1943, to support this operation.

(e) Landing-craft necessary for the operation are not available at present in sufficient quantities for the cross-Channel movement. Some 7,000 landing-craft are essential for the crossing. More should be on hand to cover losses. Only through intensification of the construction program, immediately after agreement in principle to this plan has been reached, can a sufficient number be obtained.

(f) It is mandatory that we continue to send to Russia sufficient material aid to keep that nation actively in the war.

(g) Development and construction of airfields, bases, cantonments, etc., in the British Isles in preparation for invasion of Western Europe in 1943 must be substantially completed in 1942.

12. Modified Plan

This limited operation would be justified only in case:

(1) The situation on the Russian front becomes desperate, i.e., the success of German arms becomes so complete as to threaten the imminent, collapse of Russian resistance unless the pressure is relieved by an attack from the west by British and American troops. In this case the attack should be considered as a sacrifice in the common good.

(2) The German situation in Western Europe becomes critically weakened

Because of the emergency basis on which a modified plan would be undertaken, it is impossible to predict the time for its execution. It is likewise impossible to fix the minimum scale, as to troop numbers, on which the movement might have to be initiated. It must be clear that the maximum forces that can be transported across the Channel must be employed and that local air superiority must be assured.

The following represents the scale of possible American participation, on the basis of shipping now in sight, for an invasion of France in September-October 1942:

(a) U.S. troops that can be made available in England by 15 Sept. (Figures include all troops of the Magnet Force.)

Air Forces:

400 Fighters
300 Combat other than fighters.
200 Transport.

Ground Forces:

2.5 Infantry Divisions and 1 Armored Division
or
1.5 Infantry Divisions and 2 Armored Divisions
or
1.5 Infantry Divisions, 1 Armored Division, 4 Parachute Bns, and
10 Anti-aircraft Regiments.

(b) Inclusive of the above, a total of 6 Infantry, 3 Armored, and 2 Motorized Division, 4 Parachute Battalions, and 10 Anti-aircraft Regiments will be equipped and trained in the U.S. in time to participate in this operation. If necessary shipping can be found, all the American ground forces just enumerated can be available for duty in England by early fall.

Since a large amount of troop-lift shipping becomes available late in the summer, the build-up of strength would be much more rapid after September.

(c ) British Troops

Air Forces. Execution of the 'emergency' plan would throw an additional burden upon the British, particularly their air forces, which, with the American help indicated, would have to gain and maintain air superiority over the area involved in the limited-scale attack. The minimum considered desirable, exclusive of U.S. air forces, is 2,600 fighters, 2,400 other combat types, and all available transport aircraft. However, due to the unforeseen circumstances that may demand a limited attack, even smaller air forces may be able to gain and maintain the necessary air superiority.

Ground Forces. Owing to the scarcity of landing-craft this fall, large land forces could not participate. Unless production programs are immediately intensified, it appears probable that we cannot plan on sustaining more than about five divisions, half British and half United States.