D-Day Development of Overlord ... Part 2

The Development of Overlord, D-Day 1944, part 2

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 some time 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 tl,e 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 Montgom-ery 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 tI,is 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. Bv 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,ooo-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 Aank 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 r 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. Tbese 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-9

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.

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