The Battle of Gembloux (or Battle of the Gembloux Gap) was fought between French and German forces in May 1940 during the Second World War. On 10 May 1940, The Wehrmacht, invaded Luxembourg, The Netherlands and Belgium under the operational plan Fall Gelb (Case Yellow). Allied armies responded with the Dyle Plan (Breda variant), intended to halt the Germans in Belgium, believing it to be the main German thrust. The Allies committed their best and most mobile to an advance into Belgium on 10 May and on 12 May, the Germans began the second part of Fall Gelb, the Manstein Plan an advance through the Ardennes, to reach the English Channel and cut off the Allied forces in Belgium.
Unaware that the German invasion of the Low Countries was a decoy, the French Army intended to halt the German advance into central Belgium and France on two defensive positions at the towns of Hannut and Gembloux. The French First Army, the most powerful Allied army, was to defend the Gembloux–Wavre axis. The French Corps de Cavalerie (Général René Prioux), advanced to Hannut, to screen the deployment of the rest of the First Army at Gembloux, by delaying a German advance.
After the Battle of Hannut, some 35 km (22 mi) to the north-east, the French retired towards Gembloux and the principal defensive position for the French on the Belgian front. For two days French defeated attacks by elements of the 6th Army. The German surprise attack through the Ardennes and the crossing of the Meuse at Sedan, forced the First Army to retreat from Gembloux, then back over the French frontier towards Lille. The retreat disorganised the Allied defence on the central sector of the Belgian front and the German armies occupied central Belgium. Strategically the battle was inconclusive, it diverted the First Army from Sedan, which allowed the Germans to achieve the strategic goals of Fall Gelb but the First Army survived and during the Siege of Lille diverted German forces from the Battle of Dunkirk, which allowed the British Expeditionary Force and a substantial French contingent to escape.
Background
Gembloux Gap
Between industrial northern France and Paris and the industrial Rhine-Ruhr River basin of Germany, the plain of central Belgium was a natural route of invasion. A ridge running roughly north-east to south-west through the Gembloux area forms a watershed, to the west streams flow into the Escaut (Scheldt) River and to the east into the Meuse (Maas) the area has few natural obstacles and is called the Gembloux Gap (Trouée de Gembloux).
Military theory
German
The strategy, operational methods and tactics of the German Army and Luftwaffe have often been labelled "Blitzkrieg" (Lightning War). The concept is controversial and is connected to the problem of the nature and origin of "Blitzkrieg" operations, of which the 1940 campaign is often described as a classic example. An essential element of "Blitzkrieg" was considered to be a strategic, or series of operational developments, executed by mechanised forces to cause the collapse of the defenders' armed forces. "Blitzkrieg" has also been looked on as a revolutionary form of warfare but its novelty and its existence have been disputed. Rapid and decisive victories had been pursued by armies well before the Second World War. In the German wars of unification and First World War campaigns, the German General Staff had attempted Bewegungskrieg (war of manoeuvre), similar to the modern perception of "Blitzkrieg", with varying degrees of success. During the First World War, these methods had achieved tactical success but operational exploitation was slow as armies had to march beyond railheads. The use of tanks, aircraft, motorised infantry and artillery, enabled the Germans to attempt Bewegungskrieg with a faster tempo in 1940, than that of the slow-moving armies of 1914. The internal combustion engine and radio communication solved the problem of operational-level exploitation.
The term "Blitzkrieg" is seen as an anomaly, since there was no explicit reference to such strategy, operations or tactics in German battle plans. There is no evidence in German strategic, military or industrial preparations implying the existence of a thought-out "Blitzkrieg" tendency. Evidence suggests that in 1939 and 1940 the German Reich was preparing the war economy for a war of attrition, not a quick war of manoeuvre, although there was no total economic mobilisation for the war. Hitler's miscalculations in 1939 forced him into war before the war economy was ready and under these circumstances, the German General Staff reverted Vernichtungsgedanke, attempting to win a war quickly, with swift attacks on the flanks and rear of opposing armies, leading to their destruction before the economic and material superiority of the Allies became overwhelming. It was only after the defeat of France in 1940, that the German military intentionally pursued a "Blitzkrieg"-kind of warfare to achieve its ambitions in Europe. In 2005, Karl-Heinz Frieser echoed Matthew Cooper in 1978, who had called "Blitzkrieg" a myth and that it was the weakness of German enemies not the strength of the German army, which had led to the devastating German victories early in the war. Frieser wrote:
The campaign in the west was not a planned campaign of conquest. Instead, it was an operational act of despair to get out of a desperate strategic situation. What is called "Blitzkrieg thinking" did not develop until after [author's emphasis] the campaign in the west. It was not the cause but rather the consequence of victory. Something that in May 1940, had come off successfully to everyone's surprise, was now to serve the implementation of Hitler's visions of conquest in the form of the secret success.
French
French doctrine emanated from its experiences in the First World War. With only half the population and a third of the industry of Germany, France had suffered proportionally a much higher loss, especially in those killed or permanently disabled. French doctrine therefore rested on the idea of a battle carefully controlled by senior commanders to reduce losses. Doctrine relied on defence in depth, keeping mobile forces away from enemy fire and to secure the line against incursions of enemy armour. The defence of the infantry division on open terrain was based on the artillery which would directly support the infantry and tanks; heavier pieces were reserved for use by the senior commander to make his personal intervention felt on the battlefield. Infantry was to be disposed in depth: from 15 percent to 30 percent of a division's infantry strength in outposts on commanding ground before the main position to cover it from surprises, then the main position of resistance along a natural or artificial terrain obstacle covered by the general barrage of infantry and anti-tank weapons, this position to be some 2 km (1.2 mi) deep down to a stop-line where an anti-tank screen was to be located. Units were to be emplaced on commanding terrain in closed positions capable of defence in all directions, covering the intervals between them with cross fire. Behind the stop-line would be reserves, the divisional reconnaissance battalion and the artillery battery positions in closed strong points. Defence against tanks was a priority throughout the depth of the position. A division on open terrain would hold a front 6–7 km (3.7–4.3 mi) wide and some 5 km (3.1 mi) deep.
The high command reserved battalions of infantry-support tanks for key infantry units. Leading elements of the French army trained to respond to the armoured and air threat, including those under General Henri Aymes commanding the IV Corps which fought at Gembloux. French doctrine provided for air reconnaissance and observation, fighter defence of ground forces and on occasion bomber support in principle, although they might not always be available in practice. The French forces of 1940 were far richer in artillery than in air assets and the reality overshadowed the doctrine.
Prelude
Fall Gelb
The German strategy (Fall Gelb) required the 6th Army (General Walter von Reichenau) to push its mechanised and motorised formations into the Belgian plain and strike at Gembloux, defeating or tying down Allied forces, while the main German effort was made through the Ardennes to the Meuse River (Battle of Sedan), to cut off the Allied forces in Belgium and northern France. Reichenau expected Allied motorised forces in the Dyle River–Namur area from the second day of operations, with troops brought up by railway from the fourth day. He chose to concentrate his attack between Wavre and Namur where prepared defences seemed the weakest. Luftwaffe (Air Force) medium bombers were to hinder the march of Allied units into Belgium.
Dyle plan
The French command was sure that the Germans would make their main effort (Schwerpunkt) on the Belgian plain and Grand Quartier Général (GQG), the high command planned to defeat the German move with the First Army, BEF and the Seventh Army, which contained the majority of the Allied mechanised and motorised troops. The Dyle Plan (Breda variant) covered the Allied advance into Belgium to defeat the German offensive. French doctrine opposed an encounter battle with an enemy superior in the air, nor was the command willing to invest more than a limited amount of French manpower in what was likely to prove a bloody battle.
The First Army, commanded by General Blanchard, received the critical mission of holding the Gembloux Gap. Blanchard's army would have to advance some 100 km (62 mi) from the Franco–Belgian frontier. In the process, its front would shrink from some 100 km (62 mi) to 30 km (19 mi) in the Gembloux Gap, where the Belgian army was to prepare defences for it. The powerful Corps de Cavalerie (Général René Prioux), equivalent to a German Panzer corps, was to cover the deployment of the First Army as it narrowed its front and was vulnerable to attacks by the Luftwaffe. GQG allotted Blanchard conventional infantry installed on the frontier plus advance formations of motorised infantry divisions and the 1st DCR (Division Cuirassée, Heavy Armoured Division), including some 70 heavy tanks.
Blanchard received no more than a third of the anti-aircraft weaponry he requested and decided to move his troops only at night. This meant that he would require at least eight days to dig in his infantry divisions, only three of which were motorised, before the Panzers arrived, or
it would be an encounter battle delivered under the worst conditions.
— Blanchard
General Gaston Billotte—commanding the Allied First Army Group to which the French First Army belonged—insisted that First Army have a force of powerful armour to guarantee holding the Gembloux Gap. He wanted to have two DCRs operating under an armoured corps, with the 1st DCR ready for action by the sixth day of operations. He laid down three axes of counter-attack and also warned that German tanks might attack from the sixth day of operations (they attacked one day earlier) but General Alphonse Joseph Georges—Billotte's superior—refused to commit the 2nd DCR in advance. The 1st DCR was ready for action by the morning of 14 May (the fifth day of operations). The Allies also agreed that the British Expeditionary Force would move forward between the First Army and the Belgian army, to a front along the Dyle River; the BEF planned to move both by day and by night.
An important consideration in the Allied plan was the assurance that the Belgian army would prepare defences in the Gembloux Gap in the centre of the Dyle position. The first trace of this Belgian position used the Namur—Brussels railroad line as a tank obstacle, in accordance with French intentions. As the German invasion was repeatedly postponed, the Belgian command revised the trace eastwards in the hope of "dragging" the French closer to the German-Belgian frontier and on 10 May there was only a partial anti-tank obstacle east of the Dyle line. Around Gembloux, defences barely existed; French intelligence was at least partially aware of this but the French were taken by surprise by the lack of field fortifications found on 10 May.
German offensive preparations
On the German side and forming part of Army Group B was Reichenau's 6th Army. Its forces at Gembloux were mostly first-line and experienced reservists. The divisions had been active divisions in peacetime and were filled out with reservists as war approached; they had the best equipment establishments in the Heer (German Army) and most had experienced action in the Invasion of Poland the preceding September. The formations included the XVI Corps commanded by General Erich Hoepner and the IV Corps commanded by General Viktor von Schwedler.
Hoepner's XVI Corps led the attack at Gembloux. Its forces included General Horst Stumpff's 3rd Panzer Division, which on 10 May had the 3rd Panzer Brigade with 343 tanks, the 3rd Motorised Rifle Brigade, an artillery regiment and a squadron of reconnaissance aircraft, plus engineer and service personnel. Of its 343 tanks, only 42 were medium Panzerkampfwagen; 16 Panzer IIIs and 26 heavier Panzer IVs). Generalmajor Johann Stever's 4th Panzer Division had the 5th Panzer Brigade with 331 tanks, the 4th Motorized Rifle Brigade, two artillery regiments and support forces like those of the 3rd Panzer Division. Of its 331 tanks on 10 May, only 20 were Panzer III and 24 were Panzer IV. Hoepner also disposed of the 20th Motorized Division and the 35th Infantry Division during the Battle of Gembloux.
To Hoepner's right, Schwedler's IV Corps had the 31st, 7th and 18th Infantry Divisions, from north to south. The infantry divisions′ artillery and transport units were driven mostly by horse power and they were much slower than the Panzer and Motorised divisions. During the course of the first day, XVII Corps′ 269th Infantry Division arrived, as did the 20th Motorised Division, which was used as flank protection to the south, on the Gembloux-Namur road.