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 Nazi 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 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.