PRELUDE.Following the
Invasion of Poland of September 1939 that started the Second World War, a period of inaction called the
Phoney War ("Sitzkrieg" or "Drôle de guerre") set in between the major powers.
Hitler had hoped that France and the
United Kingdom would acquiesce in his conquest and quickly make peace. This was essential to him because Germany's stock of raw materials — and of the foreign currencies to buy them — was critically low. He was now dependent on supplies from the
Soviet Union, a situation he was uncomfortable with for ideological reasons. On 6 October he made a peace offer to both Western Powers. Even before these had time to respond to it, on 9 October he also formulated a new military policy in case their reply was negative: the Führer-Anweisung N°6, or "Führer-Directive Number 6".
THE GERMANY STRATEGY.Hitler had always fostered dreams about major military campaigns to defeat the Western European nations as a preliminary step to the conquest of territory in the East, thus avoiding a
two-front war. However, these intentions were absent from the Führer-Directive N°6. This plan was firmly based on the seemingly more realistic assumption that Germany's military strength would still have to be built up for several more years and that for the moment only limited objectives could be envisaged, aimed at improving Germany's position to survive a long, protracted war in the West.
[5] Hitler ordered a conquest of the Low Countries (the
Netherlands, Belgium and
Luxembourg) to be executed at the shortest possible notice. This would prevent France from occupying them first, which would threaten the vital German
Ruhr Area. It would also provide a basis for a successful long-term air and sea campaign against the
United Kingdom. There was no mention in the Führer-Directive of any immediately consecutive attack to conquer the whole of France, although as much as possible of the border areas in northern France should be occupied.
While writing the directive, Hitler had assumed that such an attack could be initiated within a period of at most a few weeks, but the very day he issued it he was disabused of this illusion. It transpired that he had been misinformed about the true state of Germany's forces. The motorised units had to recover for an estimated three months, repairing the damage to their vehicles incurred in the Polish campaign; the ammunition stocks were largely depleted
THE MANSTEIN´S PLAN.Whilst von Manstein was formulating the new plans in
Koblenz, it so happened that Lieutenant-General
Heinz Guderian, commander of the XIXth Army Corps, Germany's elite armoured formation, was lodged in a nearby hotel.
[9] Von Manstein now considered that, should he involve Guderian in his planning, the tank general may come up with some role for his Army Corps to play in it, and this might then be used as a decisive argument to relocate XIXth Army Corps from Army Group B to Army Group A, much to the delight of von Rundstedt. At this moment
von Manstein's plan consisted in a move from Sedan to the north, right in the rear of the main Allied forces, to engage them directly from the south in full battle. When Guderian was invited to contribute to the plan during informal discussions, he proposed a radical and novel idea. Not only his army corps, but the entire Panzerwaffe should be concentrated at Sedan. This concentration of armour should subsequently not move to the north but to the west, to execute a swift, deep, independent strategic penetration towards the
English Channel without waiting for the main body of infantry divisions. This could lead to a strategic collapse of the enemy, avoiding the relatively high number of casualties normally caused by a classic
Kesselschlacht or "annihilation battle". Such a risky independent strategic use of armour had been widely discussed in Germany before the war but had not at all been accepted as received doctrine; the large number of officers serving in the Infantry, which was the dominant Arm of Service, had successfully prevented this. Von Manstein had to admit that in this special case, however, it might be just the thing needed. His main objection was that it would create an open flank of over 300 kilometres, vulnerable to French counterattack. Guderian convinced him that this could be prevented by launching simultaneous spoiling attacks to the south by small armoured units. However, this would be a departure from the basic concept of the Führer-Directive N°6.
Von Manstein wrote his first memorandum outlining the alternative plan on 31 October. In it he carefully avoided mentioning Guderian's name and downplayed the strategic part of the armoured units, in order not to generate unnecessary resistance.
[10] Six more memoranda followed between 6 November 1939 and 12 January 1940, slowly growing more radical in outline. All were rejected by the OKH and nothing of their content reached Hitler.
PLAN REVISIONS.On 10 January 1940, a German
Messerschmitt Bf 108 made a forced landing at
Maasmechelen, north of
Maastricht, in Belgium (the so-called "
Mechelen Incident"). Among the occupants of the aircraft was a Luftwaffe major, Hellmuth Reinberger, who was carrying a copy of the latest version of Aufmarschanweisung N°2. Reinberger was unable to destroy the documents, which quickly fell into the hands of the Belgian intelligence services.
[11] It has often been suggested this incident was the cause of a drastic change in German plans, but this is incorrect; in fact a reformulation of them on 30 January, Aufmarschanweisung N°3, Fall Gelb, basically conformed to the earlier versions.
[12] On 27 January, von Manstein was relieved of his appointment as Chief of Staff of Army Group A and appointed commander of an army corps in Prussia, to begin his command in
Stettin on 9 February. This move was instigated by Halder to remove von Manstein from influence. Von Manstein's indignant staff then brought his case to the attention of Hitler, who was informed of it on 2 February. Von Manstein was invited to explain his proposal to the Führer personally in
Berlin on 17 February. Hitler was much impressed by it, and the next day he ordered the plans to be changed in accordance with von Manstein's ideas. They appealed to Hitler mainly because they at last offered some real hope of a cheap victory.
The man who had to carry out the change was again Franz Halder — von Manstein was not further involved. Halder consented to shifting the main effort, the
Schwerpunkt, to the south. Von Manstein's plan had the virtue of being unlikely (from a defensive point of view) since the
Ardennes were heavily wooded and because of their poor road network, they were implausible as a route for an invasion. An element of surprise would therefore be present. It would be essential that the Allies respond as envisaged in the original plans, namely that the main body of French and British elite troops be drawn north to defend Belgium. To help to ensure this condition, the German Army Group B had to execute a holding attack in Belgium and the Netherlands, giving the impression of being the main German effort, in order to draw Allied forces eastward into the developing encirclement and hold them there. To accomplish this, three of the ten available armoured divisions were still allocated to Army Group B.
However, Halder had no intention of deviating from established doctrine by allowing an independent strategic penetration by the seven armoured divisions of Army Group A.
[13] Much to the outrage of Guderian, this element was at first completely removed from the new plan, Aufmarschanweisung N°4, Fall Gelb, issued on 24 February. The crossings of the River
Meuse at Sedan should be forced by infantry divisions on the eighth day of the invasion. Only after much debate was this changed to allow the motorised infantry regiments of the armoured divisions to establish bridgeheads on the fourth day, to gain four days. Even now the breakout and drive to the
English Channel would start only on the ninth day, after a delay of five days during which a sufficient number of infantry divisions had to be built up in order to advance together with the armoured units in a coherent mass.
Even when adapted to more conventional methods, the new strategy provoked a storm of protest from the majority of German generals. They thought it utterly irresponsible to create a concentration of forces in a position where they could not possibly be sufficiently supplied, while such inadequate supply routes as there were could easily be cut off by the French. If the Allies did not react as expected the German offensive could end in catastrophe.
[14] Their objections were ignored however. Halder argued that, as Germany's strategic position seemed hopeless anyway, even the slightest chance of a decisive victory outweighed the certainty of ultimate defeat implied by inaction.
[15] The adaptation also implied that it would be easier for the Allied forces to escape to the south. Halder pointed out that if so, Germany's victory would be even cheaper, while it would be an enormous blow to the reputation of the
Entente (as the Anglo-French alliance was still commonly known in 1940) to have abandoned the Low Countries. Moreover Germany's fighting power would then still be intact, so that it might be possible to execute Fall Rot, the main attack on France, immediately afterwards. However, a decision to this effect would have to be postponed until after a possible successful completion of Fall Gelb. Indeed German detailed operational planning only covered the first nine days; there was no fixed timetable established for the advance to the Channel. In accordance with the tradition of the
Auftragstaktik, much would be left to the judgment and initiative of the field commanders. This indetermination would have an enormous effect on the actual course of events.
In April 1940, for strategic reasons, the Germans launched
Operation Weserübung, an attack on the neutral countries of
Denmark and
Norway. The British, French, and Free Poles responded with an
Allied campaign in Norway in support of the Norwegians.
FORCES AND DISPOSITIONS.Germany Germany deployed about three million men for the battle. Because from 1919 no
conscription had been allowed by the
Treaty of Versailles, a provision which the German government had repudiated as recently as 1935, in May 1940 only 79 divisions out of a total of 157 raised had completed their training; another fourteen were nevertheless directly committed to battle, mainly in Army Group C and against the Netherlands. Beside this total of 93 front-line divisions (ten armoured, six motorised) there were also 39 OKH reserve divisions in the West, about a third of which would not be committed to battle. About a quarter of the combat troops consisted of veterans from the First World War, older than forty.
The German forces in the West would in May and June deploy some 2,700
tanks and
self-propelled guns, including matériel reserves committed; about 7,500 artillery pieces were available with ammunition stocks sufficient for six weeks of fighting. The Luftwaffe divided its forces into two groups. 1,815 combat, 487 Transport and 50 Glider aircraft were deployed to support Army Group B, while a further 3,286 combat aircraft were deployed to support Army Group A and C.
The German Army was divided into three army groups:
Army Group A commanded by Gerd von Rundstedt, composed of 45½ divisions including seven armoured, was to execute the decisive movement, cutting a "Sichelschnitt" — not the official name of the operation but the translation in German of a phrase after the events coined by
Winston Churchill as "Sickle Cut" (and even earlier "armoured scythe stroke") — through the Allied defenses in the
Ardennes. It consisted of three armies: the Fourth, Twelfth and Sixteenth. It had three
Panzer corps; one, XV Army Corps, had been allocated to the Fourth Army, but the other two (XXXXI Army Corps including the 2nd Motorised Infantry Division and XIX Army Corps) were united with XIV Army Corps of two motorised infantry divisions, on a special independent operational level in Panzergruppe Kleist. This was done to better coordinate the approach march to the Meuse river; once bridgeheads had been established across the river, the Panzer Group headquarters would be disbanded and its three corps would be divided between Twelfth and Sixteenth Army.
Army Group B under
Fedor von Bock, composed of 29½ divisions including three armoured, was tasked with advancing through the Low Countries and luring the northern units of the Allied armies into a pocket. It consisted of the Eighteenth and Sixth Army.
Army Group C, composed of 18 divisions under
Wilhelm Ritter von Leeb, was charged with preventing a flanking movement from the east, and with launching small holding attacks against the
Maginot Line and the upper
Rhine. It consisted of the First and Seventh Army.
AlliesBecause of a low
birthrate, which had even further declined during the First World War, France had a severe manpower shortage relative to its total population, which furthermore was barely half that of Germany. To compensate, France had mobilised about a third of the male population between the ages of 20 and 45, bringing the strength of its armed forces to over six million men, more than the entire German
Wehrmacht of 5.4 million. Only 2.2 million of these served in army units in the north, though the total there was brought to over 3.3 million by the British, Belgian and Dutch forces. On 10 May there were 93 French, 22 Belgian, 10 British and nine Dutch divisions in the North, for a total of 134. Six of these were armoured divisions, 24 motorised divisions. Twenty-two more divisions were being trained or assembled on an emergency basis during the campaign (not counting the reconstituted units), among which were two
Polish and one Czech division. Beside full divisions the Allies had many independent smaller infantry units: the Dutch had the equivalent of about eight divisions in independent brigades and battalions; the French had 29 independent Fortress Infantry Regiments. Of the French divisions eighteen were manned by colonial volunteer troops; nineteen consisted of "B-divisions", once fully trained units that however had a large number of men over thirty and needed retraining after mobilisation. The best trained Allied forces were the British divisions, fully motorised and having a large percentage of professional soldiers; the worst the very poorly equipped Dutch troops.
The Allied forces deployed an organic strength of about 3,100 modern tanks and self-propelled guns on 10 May; another 1,200 were committed to battle in new units or from the matériel reserves; also 1,500 obsolete
FT-17 tanks were sent to the front for a total of about 5,800. They had about 14,000 pieces of artillery. The Allies thus enjoyed a clear numerical superiority on the ground
[22] but were inferior in the air: the French
Armee de l'Air had 1,562 aircraft, and
RAF Fighter Command committed 680 machines, while
Bomber Command could contribute some 392 aircraft to operations.
[23] Most of the Allied aircraft were obsolete types; among the fighter force only the British
Hawker Hurricane and the French
Dewoitine D.520 could contend with the German
Messerschmitt Bf 109 on something approaching equal terms.
[24]At the beginning of Fall Rot, French aviation industry had reached a considerable output, and estimated the matériel reserve at nearly 2,000. However, a chronic lack of spare parts crippled this stocked fleet. Only 29% (599) of the aircraft were serviceable, of which 170 were bombers.
[25]The French forces in the north had three Army Groups: the Second and the Third defended the Maginot Line in the east; the First Army Group under
Gaston-Henri Billotte was situated in the west and would execute the movement forward into the Low Countries. At the coast was the
French Seventh Army, reinforced by a Light Mechanized (armoured) division (DLM). The Seventh Army was intended to move to the Netherlands via Antwerp. Next to the south were the nine divisions of the
British Expeditionary Force (BEF), which would advance to the Dyle Line and position itself to the right of the Belgian army. The
French First Army, reinforced by two Light Mechanized Divisions, with a Reserve Armoured Division (DCR) in reserve, would defend the Gembloux Gap. The southernmost army involved in the move forward into Belgium was the
French Ninth Army, which had to cover the entire Meuse sector between Namur and Sedan. At Sedan, the
French Second Army would form the "hinge" of the movement and remain entrenched.
The First Army Group had 35 French divisions; the total of 40 divisions of the other Allies in its sector brought their forces equal in number to the combined German forces of Army Group A and B. However, the former only had to confront the 18 divisions of the Ninth and Second Armies, and thus would have a large local superiority. To reinforce a threatened sector Gamelin had sixteen strategic reserve divisions available on General Headquarters level, two of them armoured. These were "reserve" divisions in the operational sense only, in fact consisting of high quality troops — most of them had been active divisions in peace time, and were thus not comparable to the German reserve divisions that were half-trained. Confusingly, all mobilised French divisions were officially classified as A or B "reserve divisions", although most of them served directly in the front armies.
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