The objective of Fall Gelb is … to defeat, by an attack through Belgium and Luxembourg territory, the largest possible forces of the Anglo-French army; and thereby to pave the way for the destruction of the military strength of the enemy
Führer Directive Nr. 10 for the Conduct of the War, 24 February 1940
Fall Gelb was a detailed deployment order designed to launch the initial phase of Hitler’s military campaign to eliminate the Western democracies from the European conflict. But it was only the first part of that campaign.
Because, in the Industrial Age, military campaigns could rarely accomplish strategic political aims in one decisive action – the best example of an immense failure being Germany’s ‘Schlieffen Plan’ of 1914 – typically, modern campaign plans consisted of several parallel (near simultaneous) ‘branches’ and one or more subsequent actions, called ‘sequels’. Fall Gelb was initially designed to achieve Hitler’s limited aims of acquiring a geographical position from which to further prosecute the war against both France and Britain. The sequels to this plan would be Fall Rot (Case Red) – the final conquest of France, coupled with its Italian-accommodating step-sibling Fall Braun (Case Brown) – and what we know today as the Battle of Britain, derived from the Luftwaffe’s Studie Blau (Study Blue).
Once matured, Halder’s Fall Gelb plan included four parallel branches, all to be executed simultaneously. These were as follows:
Vigorous attacks against the Maginot Line by Leeb’s Heeresgruppe C in order to pin the 24 divisions of ‘interval troops’ (including the British 51st ‘Highland’ Division) to their positions and thus prevent them from being used to attack the southern flank of the German breakthrough.
The airborne invasion of the Netherlands by the Luftwaffe’s ad hoc Luftlandekorps (‘air landing corps’) with ground relief provided by General der Artillerie Georg von Küchler’s AOK 18. Both these formations were components of Bock’s Heeresgruppe B.
The strong advance through central Belgium by the third component of Bock’s command, Reichenau’s AOK 6, designed to ‘push back any threats to the Ruhr… [and] divert to themselves the strongest possible Anglo-French forces’.
As soon as the dreadful winter of 1939/40 thawed enough to allow, German units began training in large-scale exercises, practising river crossings using the Mosel and the adjacent Eifel region to simulate the Meuse River and the Ardennes forests. (Max Schiavon)
The advance through Luxembourg and southern Belgium by the armoured formations of Rundstedt’s Heeresgruppe A designed to achieve a major breakthrough between Sedan, France, and Dinant, Belgium.
Exploitation of this breakthrough was intended to encircle the French Groupe d’Armées 1 in the north, pin them against the coastline, and result in a Kesselschlacht (‘cauldron fight’ or battle of annihilation). The infantry formations of Heeresgruppe A following behind the Panzer spearhead were to secure the southern flank of the advance by taking defensive positions along the Aisne and Somme rivers.
The Fall Gelb deployment order detailed only the initial unit dispositions and the first phase of operations, those designed to achieve the Panzer breakthrough. Subsequent operations were presented as general directions and ultimate military/geographical objectives. The plan’s Schwerpunkt was a heavy, mechanized and armoured blow aimed at the hinge point between Huntziger’s relatively static 2e Armée and Corap’s forward deploying 9e Armée, units of which had to move across portions of southern Belgium to occupy defensive positions along the Meuse River.
The armoured spearhead of this offensive was Gruppe Kleist,1 an army-level formation of two Panzer and one motorized corps, advancing in file, one corps after another. The point of the spear was Guderian’s XIX AK (mot.), consisting of three Panzer divisions and the elite Großdeutschland (‘Greater Germany’) motorized infantry regiment. Behind Guderian was Generalleutnant Georg-Hans Reinhardt’s XLI AK (mot.) with two Panzer divisions and a motorized infantry division. Security for the Panzer’s left flank was provided by General der Infanterie Gustav von Wietersheim’s XIV AK (mot.) of two motorized infantry divisions.
Following the Panzer formations was Rundstedt’s ‘leg’ infantry, hustling forward to prevent gaps from forming behind the advancing Panzers, and deploying to the left, first along the Aisne River, then later the Somme, to protect the southern flank of the armoured thrust. These were organized within List’s AOK 12 and Generaloberst Ernst Busch’s AOK 16, totalling 22 infantry divisions and one mountain division in six corps, with Weichs’s AOK 2 following, and another 45 divisions and six corps HQs behind them in the OKH reserve.
On Guderian’s right wing was General der Infanterie Hermann Hoth’s XV AK (mot.), two more Panzer divisions, ensuring that the Allied mobile forces in Belgium could not strike the Panzer spearhead’s northern flank. Hoth’s corps was part of Kluge’s AOK 4, whose nine infantry divisions trailed his Panzers through Belgium.
The key to the success of the Fall Gelb plan – as Manstein and Halder plainly saw – was the concentrated armour formation on the far left of the broad-front advance. However, without Manstein as his chief of staff to help manage Kleist’s Panzers, Rundstedt’s conservative nature and his staff’s anxieties soon constrained the mechanized forces he had so persistently requested.
As an ‘insurance policy’ Heeresgruppe A allocated to Gruppe Kleist only the four southernmost roads through the Ardennes, leaving the others for List’s infantry to march to the Meuse ‘thereby restrict[ing] the scope of the potential fiasco’. If Guderian’s Panzers bogged down in the Ardennes, they would only block the trailing Panzers; the infantry would still get to the enemy’s defensive line. Additionally Kleist was not given a sector of the front; instead his deployment operations and supply functions passed through List’s AOK 12 (hence the popular though erroneous notion that Gruppe Kleist was a component of List’s army). Finally, Rundstedt told Kleist that his command would remain independent only if it stayed ahead of List’s infantry – if not, it would be absorbed into AOK 12. Consequently Guderian’s mantra – which he drummed into all of his subordinate commanders – became ‘three days to the Meuse; on the fourth day across the Meuse’.
While Fall Gelb was an expedient designed to launch an immediate offensive, the premise of the French counter-plan was that it would be 1941 before the Allies had the strength necessary to defeat Hitler’s Wehrmacht. Therefore, the intent was to defend the French-German border with the Maginot Line while establishing an integrated forward line of defense in central Belgium to hold the Germans until a counter-offensive could be launched.
From the few secret, cursory contacts with the Belgian Army staff in November 1939, Gamelin knew that their intended main line of defence was along the Albert Canal and Maas River – a line that stretched into a large salient from Antwerp to Liège to Namur. However, Gamelin also knew that his mobile forces could not reach this line before German mechanized units overwhelmed the Belgian infantry defending it.
Therefore, Gamelin decided on an intermediate – and shorter and straighter – defensive line from Antwerp through Louvain and Wavre to Namur, Givet and Sedan. He calculated that two of his three motorized armies, the 1ère Armée and the BEF, could reach this line and establish an effective defence, provided the Belgians held the Germans at the Albert Canal–Maas line for four to seven days. Because the Louvain–Wavre section of the line was anchored on a small stream generously named the Dyle River, this Allies’ defensive deployment was called Plan D.
From the line of the Dyle–Meuse rivers Gamelin intended to fully employ the French Army doctrine of the bataille conduite (‘methodical battle’) whereby the defender’s advantages, especially in firepower (artillery and machine guns), coupled with an involved ‘deliberate planning’ process, were expected to halt the German advance. In case of a breach in the ‘continuous line of battle’ his riposte (counter-action) was the colmatage, the ‘plugging’ of the gap by moving reserves into the path of the enemy breakthrough.
The main element of the Réserve du GQG (GQG reserve) was the Allies’ third motorized formation: Général Giraud’s 7e Armée. This command – one mechanized, two motorized, and three infantry divisions – was initially positioned around Reims, behind Huntziger’s 2e Armée, able to support either Général Gaston Billotte’s Groupe d’Armées 1 along the Dyle–Meuse Line or Général André-Gaston Prételat’s Groupe d’Armées 2 behind the Maginot fortresses.
However, in the early springtime, Gamelin became worried that the Allied plan unnecessarily sacrificed the Netherlands. Believing that including the small Dutch Army in the Allies’ overall defensive array would force the Germans to divert forces to their northern flank, Gamelin willingly sacrificed his mobile reserve in order to link up with the Dutch north-east of Antwerp, at Breda. Consequently, Giraud’s 7e Armée was transferred to the far north end of the Allied line, a position from which it would race to Breda and thereby be completely unavailable to plug openings in the defensive line, wherever they might occur.
Gamelin’s decision left Georges with a weak reserve: only three recently formed and incompletely trained armoured divisions; two corps HQs with their associated artillery, engineer and reconnaissance troops; and 13 infantry divisions, only one of which was motorized.
On 20 March the ‘Dyle Plan–Breda Variant’ was issued – effectively sealing the destinies of Billotte’s southern two armies manning the Meuse defences, and with them, the fate of France.
While the Germans conducted command exercises, practice river crossings and large-scale tank manoeuvres, the French forces were kept productively employed building fortifications and tank traps. Consequently, they would not be psychologically or physically prepared for the stresses of combat. (M. Romanych)
1 Contemporarily, this formation was never known as Panzergruppe Kleist. The ‘Panzerguppe’ designation was not devised until June 1941, but it has frequently been retroactively applied to the Fall Gelb organization.