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PLANNING AND PREPARATION: DEVELOPMENT OF PLAN OVERLORD

During the period of this staff planning for OVERLORD, I was personally occupied with the Mediterranean campaigns and was not in close touch with the plans evolved for the campaign in Northwest Europe, nor did I during this period know that I would ultimately be connected with the operation. In December, however, I was notified by the Combined Chiefs of Staff that I had been appointed Supreme Commander of the Allied Expeditionary Force and that prior to assuming command in England early in January I was to return briefly to Washington for conferences with General George C. Marshall and the Combined Chiefs.

Prior to leaving my Headquarters in North Africa, I was able early in December 1943 to see a copy of the Outline Plan of OVERLORD and to discuss it with Field Marshal (then General) Sir Bernard L. Montgomery, who was to command 21 Army Group, and with my Chief of Staff, Lieut. Gen. (then Maj . Gen.) Walter B. Smith. I instructed them to consider the plan in detail upon their arrival in England because, while agreeing with the broad scope of the operation and the selection of the assault area, I nevertheless felt that the initial assaulting forces were being planned in insufficient strength and committed on too narrow a front. This they did, and shortly after my arrival in London on 15 January, I was able, with them and my other commanders, to reach an agreement which altered the OVERLORD operation in this respect.

While my appointment as Supreme Commander did not become official until the receipt of a directive from the Combined Chiefs of Staff on 14 February, and while the status of my Headquarters-to be known as SHAEF-was not recognized until the following day, the basic work of planning continued during this transitional period. The staff brought into being as COSSAC came under my control and was greatly expanded as the pressure of time and the vast scope of our work required.

I patterned my Headquarters upon the closely integrated Allied establishment which it had been my policy to maintain at AFHQ in the Mediterranean, and in this respect I was fortunate in obtaining for my staff men whose proved ability had already been demonstrated in previous campaigns - Air Chief Marshal Sir Arthur W. Tedder as my Deputy Supreme Commander, General Smith as my Chief of Staff, and Lieut. Gen. Sir Humfrey M. Gale as Chief Administrative Officer. General Morgan remained as Deputy Chief of Staff, his detailed knowledge of tactical plans making him absolutely indispensable.

Relationship between SHAEF and the Headquarters of my Commanders-in-Chief for the Navy, Army, and Air Forces was established on the operational planning level through a Joint Planning Staff which closely integrated the work of all. The Headquarters of COSSAC had been located at Norfolk House, St. James's Square, with an annex at 80, Pall Mall, and it was here initially that my own Headquarters came into being. However, I was convinced by past experience that a Headquarters located in the heart of a great city would not be as unified as one located elsewhere. Accordingly SHAEF was moved in March to Bushy Park, near Kingston-an-Thames. Here we studied the operation in detail and ironed out all the numerous and frequently vexing problems relating to so vast an undertaking.

The chief changes which we were to make in the assault plan were considered at the first meeting which I held with my Commanders-in-Chief at Norfolk House on 21 January. Field Marshal Montgomery (Commanding General, 21 Army Group), Admiral Sir Bertram H. Ramsay (Commander of the Allied Naval Expeditionary Force), and Air Chief Marshal Sir Trafford Leigh-Mallory (Commander of the Allied Expeditionary Air Force) reviewed operation OVERLORD as a whole with me and were in agreement upon certain amendments to the plan.

The COSSAC plan called for an initial assaulting force of three divisions. I had felt when I originally read the OVERLORD plan that our experiences in the Sicilian campaign were being misinterpreted, for, while that operation was in most respects successful, it was my conviction that had a larger assault force been employed against the island beachheads our troops would have been in a position to overrun the defenses more quickly. Against the better prepared defenses of France I felt that a three-division assault was in insufficient strength, and 3 that to attain success in this critical operation a minimum of five divisions should assault in the initial wave. Field Marshal Montgomery was in emphatic agreement with me on this matter, as were also Admiral Ramsay and Air Chief Marshal Leigh-Mallory, even though a larger assault force raised great new problems from both the naval and air points of view.

In addition to increasing the assault force from three to five divisions, I felt that the beach area to be attacked should be on a wider front than that originally envisaged. Particularly, it was considered that an attack directly against the Cotentin Peninsula should be included in the plan, with a view to the speedy conquest of Cherbourg. In the event that our troops were able to attain a high degree of surprise in the attack, they would be in a better position to overwhelm the strungout defenses before the enemy could regroup or mass for a counterattack. Conversely, in the event of strong resistance, we would be more advantageously situated, on a wider front and in greater force, to find "soft spots" in the defense.

The original COSSAC plan included the beachhead areas from Courseulles in the east to Grandcamp in the west. We decided to extend this area eastward to include the Ouistreham beaches, feeling that this would facilitate the seizure-by rapidly securing the eastern flank--of the important focal point of Caen and the vital airfields in the vicinity. Westward, we decided that the assault front should be widened to include the Varreville beaches on the eastern side of the Cotentin Peninsula itself. A strong foothold on the peninsula and a rapid operation to cut its neck would greatly speed up the capture of the port of Cherbourg.

For the operation against the neck of the Cotentin to be successful, it was believed that two airborne divisions should be employed in support of the troops assaulting the Varreville beaches, still leaving one airborne division to hold vital bridges in the Orne-Dives Rivers area to the northeast of Caen. Field Marshal Montgomery and Admiral Ramsay were in agreement on this point, but Air Chief Marshal Leigh-Mallory saw technical difficulties which it was necessary to consider closely.

It was his feeling, both then and subsequently, that the employment of airborne divisions against the South Cotentin would result in landing losses to aircraft and personnel as high as 75%-80%. In the face of this estimate, however, I was still convinced of the absolute necessity of quickly overrunning the peninsula and attaining the port of Cherbourg, vital to the support and maintenance of our land forces. Without the airborne divisions an assault against the Varreville beaches would have been most hazardous, since our attack here could only be on a one-division front. Behind the landing beach was a lagoon, traversed only by a few causeways; the exits of these had to be captured from the rear, or else the strip of beach would quickly become a death trap. In addition, this beach was separated from the other four beaches to be assaulted by an estuary and marsh lands which would have effectively prevented the junction and link-up of the forces for several days, permitting the enemy in this sector more easily to dislodge us and threaten our right flank. Support by the airborne troops was essential, and I ultimately took upon myself the heavy responsibility of deciding that the airborne operation against the Cotentin be carried out. The decision, once taken, was loyally and efficiently executed by the airborne forces, and it is to them that immeasurable credit for the subsequent success of the western operation belongs. The airborne landing losses proved only a fraction of what had been feared, amounting in fact to less than 10%.

Our decisions to strengthen the forces employed in the initial assault, to widen the area of attack, and to employ the airborne forces in the Cotentin rather than at Caen, were communicated to the Combined Chiefs of Staff on 23 January, and at the same time I brought up the subject of the target date for the operation.

In the original plan, the target date for the D-day assault had been 1 May. A new factor, however, which made me doubt that the date could be adhered to was our deficiency in assault craft for the larger five-division attack. In the COSSAC plan, three divisions in the assault and two immediate follow-up divisions, a total of five, were to be preloaded in assault craft. Sufficient craft for five divisions had been planned. The new plan, calling for five divisions in the assault, still retained the two follow- up divisions, requiring therefore sufficient craft to preload seven divisions. There was considerable doubt that the additional craft could be made available by I May, and I informed the Combined Chiefs of Staff that, rather than risk failure with reduced forces on that date, postponement of the target date for a month would be preferable if I could be assured of then obtaining the strength required. My planners had advised me that a month's additional production of assault craft in both Great Britain and the United States would go far toward supplying the deficiency foreseen for the earlier date.

From the air point of view, the extension of the target date would afford a longer opportunity for the strategic bombing of Germany and the wearing down of German air strength. In addition, the tactical bombing of railheads and transportation centers, the preliminary softening of fortifications on the Channel coast, and the diversionary heavy air attacks in the Pas-de-Calais could be undertaken with greater thoroughness. The training of the invasion forces, and particularly the troop-carrier crews for the airborne operations, could also be carried on more thoroughly.

The Navy, moreover, desired additional time for the training of the assault craft crews and for the delivery and assembly of the extra vessels needed in the enlarged attack. From the naval viewpoint a postponement of the target date to the first of June was preferable to any briefer postponement, say of two weeks, since an early June date guaranteed the favorable tides necessary for the beach operations as well as a full moon.

From the strategic point of view the postponement seemed desirable, since weather conditions at the end of May would be likely to be more favorable for the mounting of a large-scale Russian offensive to assist the OVERLORD operation. Additionally, the situation in the Mediterranean might be sufficiently resolved by that time to preclude the necessity of an operation against the south of France closely coordinated with our western assault. The German forces in that theater might be so heavily engaged by our armies that a diversionary and containing assault would not be required in direct and immediate assistance to OVERLORD.

The Combined Chiefs of Staff agreed on 1 February that OVERLORD would be mounted with a target date not later than 31 May. We indicated that the exact date of the assault should be left open and subject to weather conditions prevailing during the first week of June. Later, on 17 May, I set 5 June as the "final" date for the assault, subject, of course, to last-minute revision if the weather should prove unfavorable. The selection of this date was based primarily on tidal and light conditions. It was necessary that the tide be sufficiently low to enable the initial assault elements to land and prepare lanes through the heavy obstacles which were above water only at or near a low tide. Also, this tidal condition had to coincide with a period of sufficient light to permit visual bombing by aircraft of the beach defenses and bombardment by the naval vessels. The dates of 5, 6, and 7 June were all acceptable on this basis, but any postponement beyond these dates would have necessitated waiting until 19 June for a similar favorable tidal period. This later date would have necessitated the acceptance of moonless conditions.

Strategically, the postponement of the target date proved to be a sound measure. By 1 May, the original date, our forces in Italy were still encountering heavy resistance south of Rome along the Gustav Line, while Russian forces were occupied in the Crimea and still forming for a western attack. By the first week in June, however, Rome had fallen, Kesselring's forces were in retreat, the Crimea had been cleared, and Germany was nervously predicting an all-out Russian offensive. Furthermore, the enemy had been keyed up to a 1 May Allied offensive from the United Kingdom, to judge from his "invasion any day now" feelers. The month's delay served perhaps to lull him into believing that we would now not attack until sometime in July. The month's postponement also guaranteed, as events proved, the availability of assault craft and shipping to move the staggering number of men and vehicles required for the D-day assault.

It should be noted here, however, that had it been possible to adhere to the initial date, the weather would have been much superior for the invasion than was the weather encountered during the first week of June. During the first week of May, in the full-moon period, the Channel was consistently calm and the skies cloudless, ideal both for naval and air operations. The weather was strikingly similar to that which favored England during the disastrous days of Dunkirk. In the first week of June, on the other hand, the Channel was choppy at best, with heavy seas running most of the time. The skies were overcast, and days of rain hampered air operations. The full extent to which this unfavorable weather influenced our operations will be considered later in this report.

With the settlement of the basic problems essential to firm planning-the size of the assault and the target date-the Army, Navy, and Air Forces were in a position to develop their final plans for the attack against the Normandy beaches. The best method of controlling the effort of the Strategic Air Forces was still under discussion and will be referred to later in the section on "Preparatory Operations." Immediately under my command in the pre-D-day period were the Commanders-in-Chief already mentioned, Field Marshal Montgomery, Admiral Ramsay, and Air Chief Marshal Leigh-Mallory.

Within 21 Army Group, Field Marshal Montgomery had under his command the Canadian First Army (2 Corps) under Lieut. Gen. H. D. G. Crerar; the British Second Army (I, 8, 12, and 30 Corps) under Lieut. Gen. (then Maj. Gen.) Sir M. C. Dempsey; the British airborne troops (I and 6 Divisions) under Lieut. Gen. F. A. M. Browning; and the United States First Army V, VII, VIII, and XIX Corps, with the attached airborne troops of the 82d and 101st Divisions) under General (then Lieut. Gen.) Omar N. Bradley. While plans called for eventual organization of American and British ground forces each under its own commander, directly responsible to me, the initial assault was foreseen as a single battle, closely interrelated in all its parts, and requiring the supervision of a single battle-line commander. All agreed on this necessity.

The army plans for the assault and subsequent build-up period were prepared, pursuant to periodical directives from Supreme Headquarters, by the planning staffs of the American and British Army Headquarters, coordinated by 21 Army Group Headquarters, and subsequently reviewed by the G-3 Division of my staff under Maj. Gen. H. R. Bull and his deputy, Maj. Gen. J. F. M. Whiteley. Constant revision of the plans was necessary throughout the early months of 1944, due primarily to the continuing uncertainty as to the exact number of assault craft to be made available for the loading of the troops. Even with the extra month's production of craft in both the United States and the United Kingdom, it seemed that sufficient lift would not be forthcoming, and it became necessary during this period to consider drawing craft from either the Mediterranean or the Pacific to round out the figure needed. This entailed a constant exchange of views between Theaters and between my Headquarters and the Combined Chiefs of Staff until the problem was finally settled-as late as 24 March. Since the problem was also related to the mounting of Operation ANVIL, the assault against Southern France from the Mediterranean, reference will be made to the matter again in this report. Suffice it to say here, however, that before firm planning can be undertaken on any major amphibious operation, involving, as such an operation does, the forces of both the Army and the Navy, the primary factor of assault craft must be definitely determined. This decision should be made as early as humanly possible, for it is a matter of the first priority.

Based upon the COSSAC plan for the assault, together with the revisions as to date and size of attack which have been mentioned, the final plan produced by 21 Army Group and approved by Supreme Headquarters thus came into being.

Broadly, the army plan of attack involved a D-day assault on a five-divisional front on the beaches between Ouistreham and Varreville with the immediate purpose of establishing beachheads to accommodate follow-up troops. The initial objectives of the attack included the capture of Caen, Bayeux, Isigny, and Carentan, with the airfields in their vicinity, and the essential port of Cherbourg. Thereafter our forces were to advance on Brittany with the object of capturing the ports southward to Nantes. Our next main aim was to drive east on. the line of the Loire in the general direction of Paris and north across the Seine, with the purpose of destroying as many as possible of the German forces in this area of the west.

Because it was ultimately intended to supply the United States forces engaged in Europe directly from American ports, American troops were assigned the right flank in the operations. They were to take Cherbourg and the Brittany ports as supply bases, while the British, driving east and north along the coast were to seize the Channel ports, as far north as Antwerp, through which they were to be supplied directly from England.

On the right, American forces of General Bradley's First Army were to assault the Varreville (Utah) beach and the St-Laurent (Omaha) beach. Lieut. Gen. (then Maj. Gen.) J. Lawton Collins' VII Corps was to land with the 4th Infantry Division in the assault on Utah beach just north of the Vire Estuary. During the early morning hours of D-day the 82d and 101st Airborne Divisions were to drop in the area southeast and west of Ste-Mere-Eglise where their mission was to capture the crossings of the Merderet River, secure the line of the Douve River as a barrier, and assist the landing of the 4th Infantry Division at the Beach. By the end of D-day, we anticipated that VII Corps, With the airborne divisions under command, would control the area east of the Merderet from just south of Montebourg to the Douve.

Lieut. Gen. (then Maj. Gen.) Leonard T. Gerow's V Corps planned its attack on a 7,000-yard stretch of beach known as Omaha, on the northern coast of Calvadas near St-Laurent. One combat team of the 29th Infantry Division on the right and one combat team of the 1st Infantry Division on the left, both under the command of the 1st Infantry Division, were to assault in the initial wave.

The primary objective of VII Corps, supported by the airborne divisions, was to cut the Cotentin Peninsula against attack from the south, and, driving northward, to seize the port of Cherbourg-we hoped by D-plus-8. While Cherbourg was being taken, troops of V Corps and follow-up forces were to drive south toward St-Lo, seizing the city by D-plus-9. With the reduction of the Cotentin Peninsula, the forces engaged there and follow-up forces subsequently landed were also to turn south, join with the forces landed over Omaha, and drive to a line Avranches-Domfront by approximately D-plus-20.

Forces of General (then Lieut. Gen.) George S. Patton's Third Army were, during this period, to be landed across the American beaches and initially come under the operational control of First Army, passing to the control of Third Army when its Headquarters moved to the Continent at about D-plus-30. While First Army was to make an initial turning movement into the Brittany Peninsula in the direction of St-Malo, it was planned that Third Army, with its growing forces, would take over the reduction of the peninsula and the Brittany ports from First Army on this same date. First Army, then, freed of the responsibility for Brittany, was to turn its forces south and east along the Loire, reaching a line beyond Angers-Le-Mans by D-plus-40.

British and Canadian forces, landing on the Ouistreham (Sword), Courseulles (Juno), and Asnelles (Gold) beaches were in the meantime to protect the left flank of the Allied forces against what was expected 10 be the main German counterattack from the east. An additional important task was to gain the ground south and southwest of Caen, favorable for the development of airfields and for the use of our armor. The first assault was to be made by three divisions of General Dempsey's British Second Army: the 3 Canadian and 3 British Infantry Divisions of I Corps, and the 50 Infantry Division of 30 Corps. British 6 Airborne Division was to be dropped behind the beach defenses to secure the vital bridges over the Caen Canal and the Orne River between Caen and the sea, together with certain other objectives in that locality. These forces with follow-up troops, advancing southward, were to occupy territory inland to a line Vire-Falaise, including the Caen road center, by about D-plus-20.

After occupation of this area, the British forces were to continue expansion along the general line of the Seine, advancing on the left of the American divisions until, by D-plus-90, the general Allied front was to stand on the Seine from Le Havre to Paris on the north, and along the Loire from Nantes to Orleans, Fontainebleau, and Paris on the south and east. In the west the Brittany Peninsula was to be fully occupied. By D-plus-90 the armies were to be ready to take Paris, force the crossing of the Seine in strength in an advance northward to the Somme, and continue east along the Marne in a drive toward the German frontier.

Early in May 1944 after I had approved Field Marshal Montgomery's plans for establishing our forces on the Continent, and for placing them in position prepared for eruption from the lodgement area, the planning staff presented their visualization of the several lines of action which might be followed for the continuance of the campaign, up to and including the final period, for a drive into the heart of Germany. The favored line of action was sketched on a map of the Continent. It contemplated an advance on a broad front with the main effort constantly on the left (north) flank and with another thrust toward Metz, passing north and south of Paris in the event the Germans determined to hold it as a fortress, joining up with Gen. Jacob L. Devers' forces coming from the south to cut off Southwest France; penetration of the Siegfried Line, still with the main effort in the north; elimination of the German forces west of the Rhine either by decisive defeat or by pressure which would force their withdrawal, with particular emphasis on the area from Cologne-Bonn to the sea; a power crossing of the Rhine north of the Ruhr, coupled with a secondary effort via the Frankfurt Corridor, the two thrusts to join in the general area of Kassel, encircling the Ruhr. Thereafter it was anticipated that the destruction of remaining German strength would be easy.

This estimate made at this early date is particularly interesting since the proposed scheme of maneuver was practically identical with that which was followed during the campaign.

Later in this report is described the supporting air plan, success in which was vital to the attainment of the ambitious objectives prescribed for the land forces. Also necessary to an understanding of the whole battle is a knowledge of the information we possessed, prior to the assault, regarding the enemy dispositions, a summary of which is also included in a subsequent chapter.

In the initial phases of OVERLORD, Field Marshal Montgomery, whom I had designated as tactical commander of the early land battles, was to have operational control of all land forces, including the United States First Army until the growing build-up of the American forces made desirable the establishment of an independent Army Group. When sufficient forces had disembarked on the Continent, a United States Army Group was to come into being, equal both operationally and administratively to the British 21 Army Group, which latter was to continue under Field Marshal Montgomery's command. Although no definite time was set for this, it was estimated that it would take place when the Third Army had become fully operational; the date was also dependent, of course, upon the progress of the initial land battles beyond the beachhead area where, as already pointed out, simplicity of command in a narrow space was desirable.

In the matter of command, it can be said here that all relationships between American and British forces were smooth and effective. Because of certain fundamental national differences in methods of military supply and administration, it was early agreed that no unit lower than a corps of one nationality would be placed under command of the other nationality except where unavoidable military necessity made this imperative.

To carry out the mission of invading Western Europe, there were to be available, by D-day, in the United Kingdom 37 divisions: 23 infantry, 10 armored, and 4 airborne. These were to be employed in the assault and subsequent build-up period in France.

As the campaign progressed, the flow of divisions to the Continent was to be maintained at a rate of three to five divisions per month, and this flow was to be augmented by the divisions entering the European Theater with the assault against Southern France from the Mediterranean. [These were the 3rd, 36th and 45th US Infantry Divisions.] Ultimately, at the time of the German surrender, I had under command a total of go divisions: 61 American, 13 British, 5 Canadian, 10 French, and 1 Polish. These divisions, with antiaircraft, antitank, and tank units habitually attached, averaged about 17,000 in combat strength, well over twice the strength of Russian divisions. In addition there were three French divisions which were not completely equipped, and lesser units of Czech, Belgian, and Dutch forces on the Continent, as well as the units of the French Forces of the Interior. Our Headquarters estimated that, at times, the value of these latter French forces to the campaign amounted in manpower to the equivalent of 15 divisions, and their great assistance in facilitating the rapidity of our advance across France bore this out.

The initial success of the land forces in the assault against Northwest Europe was dependent upon the operations of the Allied Naval Expeditionary Force under the command of Admiral Ramsay. In his operational orders issued on 10 April, he clearly defined the Navy's mission to those under his command: "The object of the Naval Commander-in-Chief is the safe and timely arrival of the assault forces at their beaches, the cover of their landings, and subsequently the support and maintenance and the rapid build-up of our forces ashore." To accomplish this mission successfully months of de• tailed planning and training, closely coordinated with the ground and air forces, were necessary.

Reports on the North African and Sicilian Campaigns have made mention of the magnitude of the naval forces involved, but the sea power displayed there was to fade by comparison with the forces to be employed in this great amphibious assault. The extent of the problem of berthing, loading, and moving the forces involved may be realized With the knowledge that over 5,000 ships and 4,000 additional "ship-to-shore" craft were to be engaged in the Channel operations during the assault and build-up period. That everything went according to plan is a remarkable tribute to the hard work, coordinated effort, and foresight of the thousands engaged in the initial planning and training, and, as Admiral Ramsay stated in his report, to the "courage of the tens of thousands in the Allied navies and merchant Beets who carried out their orders in accordance with the very highest traditions of the sea."

With the expansion of the assault from a three-divisional to a five-divisional attacking force, increased naval forces were necessary both to protect the invasion Fleet en route and to bring added fire power to bear on the beaches. These were allotted by the Combined Chiefs of Staff on 15 April 1944. The chief units in the final naval forces included 6 battleships, 2 monitors, 22 cruisers, and 93 destroyers.

Under the naval plan the assault area for the naval forces was bounded on the north by the parallel of 49° 40' N, and on the west, south, and east by the shores of the Bay of the Seine. This area was subdivided into two Task Force Areas, American and British, the boundary between them running from the root of the Port-en Bessin western breakwater in an 0250 direction to the meridian of 0°4°' W, and thence northward along this meridian to latitude 49°40' N. Within these defined areas, the Western Task Force, operating in the American zone, was under the command of Rear Adm. A. G. Kirk, and the Eastern Task Force, operating in the British zone, under the command of Rear Adm. Sir P. L Viano The Western and Eastern Task Forces were again subdivided to include, altogether, five assault forces, each responsible for the landing of an assault division upon one of the five beach areas, and two follow-up forces. The assault forces were known for the American zone as Force "U" and Force "O" (Utah and Omaha) and were under the command respectively of Rear Adm. D. P. Moon and Vice Adm. (then Rear Adm.) J. L. Hall, Jr. For the British zone the assault forces were similarly known as Force "S", Force "J", and Force "Gil (Sword, Juno, and Gold) and were commanded by Rear Adm. A. G. Talbot, Commodore G. N. Oliver, and Rear Adm. C. Douglas-Pennant.

In order to insure the safe arrival of the assault troops on the beaches, the Navy was to provide adequate covering forces to protect the flanks of the routes of our assault and was, with mine sweeping vessels, to clear the Channel ahead of the assault craft. For this latter purpose I 2 mine sweeping flotillas were to be employed. Once within range of the beachhead area, the heavy naval guns were to neutralize the enemy coastal batteries, supplementing the work of the Air Forces, and then, as the landing craft drove inshore, there was to be an intense bombardment of the beach defenses by every gun that could be brought to bear.

Some consideration had initially been given to the possibility of assaulting at night in order to obtain the maximum surprise, but it was decided that the lessons of the Pacific should be adhered to, and that, possessing superiority in air and naval forces, the assault against strong defenses should take place by day. This was palpably advantageous to the Navy in the coordinated movement of a vast fleet in relatively narrow waters. H-hour varied for most of the five assault forces, due to varying beach conditions such as the necessity for higher tide to cover certain rock obstacles and the length of time needed to remove enemy obstructions. Force "U" was to touch down at 0630 hours while Force "J" was not to land until 35 minutes later.

With the success of the assault determined, the naval forces were to maintain swept channels between France and England through which supplies and reinforcements could be shuttled to the Continent. In view of the initial limited port facilities and the fact that we did not anticipate seizing the Brittany ports for some time after the assault, the Navy was also charged with providing for the establishment off the French coast of five artificial anchorages (Gooseberries). Two of these were subsequently to be expanded into major artificial harbors (Mulberries); through these the bulk of our stores were to be unloaded during the early stages of the campaign. To provide oil and gasoline in bulk, the Navy was also to set up tanker discharge points off the French coast and to establish cross-Channel submarine pipe lines.

By 26 April, the five naval assault forces were assembled in the following areas: Force "U," Plymouth; Force "0," Portland; Force "S," Portsmouth; Force "G," Southampton; and Force "J," Isle of Wight. The two follow-up forces, Force "B" and Force "L," were assembled in the Falmouth-Plymouth and Nore areas. in addition to the berthing problems inherent in the assembly of these seven forces, other space had to be found for the many ships and craft which were assigned the tasks of supply, maintenance, repair, and reinforcement. The berthing problem was one of major proportions, but it was solved, as Admiral Ramsay reported, by making use of every available berth from Milford Haven to Harwich. Many units had, additionally, to be berthed in the Humber, at Belfast, and in the Clyde.

The concentration of ships in southern ports was bound, we felt, to be detected by the enemy and would thus give him some indication that our assault was about to be launched. In order to confuse him in this respect, arrangements were made with the British Admiralty to have the large number of commercial ships destined for the Thames and also the ships to be used in later supply convoys to our forces on the Continent held in Scottish ports until the operation was under way. The concentration of shipping thus spread itself automatically throughout the whole British Isles and was not confined to a single area. As was the case against Sicily, we did not believe that the growing preparations and the size of our forces could be entirely concealed from the enemy. We hoped, though, to be able to confuse him as to the time of the assault and the exact beachhead area of attack. In this we were to be successful for a variety of reasons which I shall consider later.

The air plan in support of the amphibious operation consisted of two parts, the preparatory phase and the assault phase, and was brought into being under the direction of Air Chief Marshal Leigh-Mallory, commanding the Tactical Air Forces. These forces, composed of the British Second Tactical Air Force and the U. S. Ninth Air Force, were to operate in direct support of the land armies. The Strategic Air Forces also would be given definite tactical responsibilities during critical periods, although their principal mission would be to continue their attacks on the industrial potential of Germany, with emphasis now placed on the facilities for aircraft production. They had also definite tactical responsibilities at critical periods of the battles.

Until January 1944, the view had been held that the heavy bombers of the Strategic Air Forces could make sufficient direct contribution to the assault in a period of about a fortnight before D-day. Further consideration, however, indicated the need to employ them for a much longer period-about three months-and a plan was finally adopted which aimed at the crippling of the French and Belgian railway systems and the consequent restriction of the enemy's mobility. The plan had a wider conception than the dislocation of the enemy's lines of communication in the zone in which the land forces were to be deployed. It was looked upon as the first of a series of attacks, which as they spread eastward, would ultimately affect the whole German war effort. The adoption of this plan entailed a major effort by the Strategic Air Forces.

In the preparatory phase, the striking power of the Tactical Air Forces was to be directed against rail targets, bridges, airfields in the vicinity of the assault area, coastal batteries, radar stations, and other naval and military targets. In addition to reserve aircraft, these forces had operationally available 2,434 fighters and fighter-bombers, and 700 light and medium bombers.

The program of attack on rail centers and bridges was designed to deprive the enemy of the means for the rapid concentration of men and material and to hinder his efforts to maintain an adequate Row of reinforcements and supplies, forcing him to move by road with resultant delay, increased wastage in road transport and fuel, and increased vulnerability to air attack. Blows against the railroad centers were to be started about D-minus-60 and were to cover a wide area so as to give the enemy no clue to our proposed assault beaches. Shortly before D-day, however, the attacks would be intensified and focused on key points more directly related to the assault area hut still so controlled as not to indicate to the enemy the area itself.

Attacks against coastal batteries, airfields, bridges, and other targets in the preparatory period were planned in such a manner that only one-third of the effort expended would be devoted to the targets threatening the success of our assault. The preliminary attacks upon the bridges in Northwestern France were scheduled to begin on D-minus-46 and to be intensified in tempo as D-day approached. The ultimate purpose of these at-tacks was to isolate the battle area from the rest of France by cutting the bridges over the Seine and the Loire below Paris and Orleans, respectively. The attacks upon the airfields had a similar purpose. Within a 130-mile radius of the battle area, all enemy airfields and air installations were to be attacked beginning not later than D-minus-21. By neutralizing the fields, we were certain to limit the maneuverability of German fighter forces, compelling them to enter the battle from fields situated a considerable distance from the Normandy beaches.

This preparatory bombing program was placed in effect as scheduled and, as D-day approached, the intensity of our attacks increased and the preparatory phase gave way to the assault phase. In the assault itself, the air forces were assigned the tasks, in conjunction with the navies, of protecting the cross-Channel movement of our forces from enemy air and naval attack. They were also to prepare the way for the assault by destroying the enemy's radar installations and by neutralizing coastal batteries and beach defenses between Ouistreham and Varreville, the area of our attack. Additionally, the air forces were to provide protective cover over the landing beaches and, by attacking the enemy, reduce his ability to reinforce and counterattack. Subsequent to the establishment of the beachhead, the Tactical Air Forces were to support the land troops in their advance inland from the assault beaches.

During the assault it was planned to maintain a sustained density of ten fighter squadrons to cover the beach area, five over the British sector and five over the American. An additional six squadrons were to be maintained in readiness to support the beach cover if necessary. Over the main naval approach channels we agreed upon a sustained density of five squadrons centered at 60 miles and three at 80 miles from the South coast of England. Additionally, a striking force of 33 fighter squadrons was to be held in reserve for use as the air situation might require, subsequent to its initial employment as escort to the airborne formations.

The total fighter aircraft which we allocated for the D-day assault was as follows:
Beach Cover (54 Squadrons)
Shipping Cover (15 Squadrons)
Direct Air Support (36 Squadrons)
Offensive Fighter Operations and Bomber Escort (33 Squadrons)
Striking Force (33 Squadrons)
for a Total of 171 Squadrons.

The photographic reconnaissance units of the Allied Air Forces were the first to begin active and direct preparations for the invasion of Europe from the west. For more than a year, much vital information was accumulated which contributed very greatly to the ultimate success of the assault. The variety, complexity, and the detailed accuracy of the information gathered was of great importance in the preparatory phase of the operation. One of the most remarkable tasks accomplished by these reconnaissance units was the series of sorties flown to obtain low-level obliques of underwater beach defenses.

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INTRODUCTION





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