The fighting at Hannut formed the opening struggle for the Gembloux Gap. As attacking German armoured forces drove hard into Belgium, Allied armies advanced to meet them.
The Dyle Plan brought the Allied left wing forward into Belgium, while Prioux’s Corps de Cavalerie screened the approaches to the Gembloux Gap.
The Allied Advance into Belgium
When Germany opened its western offensive on 10 May 1940, the campaign in Belgium formed part of a larger operational design. The German high command intended to draw the main Allied armies forward into central Belgium, where they would be fixed in place, while the decisive blow developed farther south. For the Allies, however, the threat through Belgium was real and immediate. The plains east of Brussels and the open country around the Gembloux Gap offered one of the best routes for a rapid advance into northern France. If the Germans reached that ground before the Allied armies had taken position, the consequences could be severe.
The Dyle Plan
The Allied response was the Dyle Plan. Under this plan, the French First Army and the British Expeditionary Force were to advance into Belgium and establish a defensive line running from Antwerp through Louvain and Wavre to the Gembloux Gap. This was an ambitious move. It aimed to meet the Germans head-on, defend Belgian territory, and hold a shorter, more favourable line than one based farther back on the French frontier. The weakness of the plan lay in time and distance. The Allied armies had to move quickly, deploy in the open, and be ready to fight before the Germans could disrupt the process.
Prioux’s Covering Force
To gain that time, the French sent forward Prioux’s Corps de Cavalerie, built around 2e and 3e Divisions Légères Mécaniques. These mechanised cavalry divisions were ordered to cover the advance of the First Army by screening the Belgian frontier, identifying the German thrust, and delaying the enemy long enough for the main Allied line to be organised around Gembloux. Their task was to trade ground for time.
The Road to Hannut
On the Hannut axis, 3e Division Légère Mécanique spread across the road net west of the frontier. Its reconnaissance regiment, 12e Régiment de Cuirassiers, operated with Panhard 178 armoured cars, while the division’s tank strength lay with 1er Régiment de Cuirassiers and its Somua S35s, and 2e Régiment de Cuirassiers with Hotchkiss H35/H39 tanks. Opposing them were the forward elements of Aufklärungs-Abteilung 7, probing ahead of 4. Panzer Division with reconnaissance troops and light tanks from Panzer Regiment 35.
Key Forces France Corps de Cavalerie 2e DLM 3e DLM Germany XVI. Armeekorps (mot.) 3. Panzer Division 4. Panzer Division
The Gembloux Gap
The Gembloux Gap was one of the most important operational corridors in Belgium. Unlike the more enclosed terrain farther north and south, the Gap offered broad, open ground well suited to rapid movement by mechanised forces. If German armour reached it before the Allied line had formed, the road into the rear of the Allied left wing would lie open. For that reason, Prioux’s cavalry screen had a clear purpose: delay the German advance long enough for the French First Army to occupy the Gembloux position in strength.
