Battle of Hannut

The Battle of Hannut was a Second World War battle fought during the Battle of Belgium which took place between 12 and 14 May 1940 at Hannut in Belgium. It was the largest tank battle in the campaign. It was also the largest clash of tanks in armoured warfare history at the time.

The primary purpose of the Germans was to tie down the strongest elements of the French First Army and keep it away from the main German attack by Army Group A through the Ardennes, as laid down in the German operational plan Fall Gelb (Case Yellow), by General Erich von Manstein. The German breakout of the Ardennes was scheduled for 15 May, five days after the German attacks on the Netherlands and Belgium. The delay was to entice the Allies into believing the main thrust would, like the Schlieffen Plan in World War I, come through Belgium and then down into France. When the Allied armies advanced into Belgium according to the Dyle Plan, they would be tied down by German offensive operations in eastern Belgium at Hannut and Gembloux. With the flank of the First Army exposed, the Germans could thrust to the English Channel which would encircle and destroy the Allied forces. For the French, the plan in Belgium was to prepare for a prolonged defence at Gembloux, about 34 km (21 mi) west of Hannut. The French sent two armoured divisions forward, to conduct a delaying action against the German advance and give the rest of the First Army time to dig in at Gembloux.

The Germans reached the Hannut area just two days after the start of the invasion of Belgium but the French defeated several German attacks and fell back on Gembloux as planned. The Germans succeeded in tying down substantial Allied forces, which might have participated in the Battle of Sedan, the attack through the Ardennes. The Germans failed to neutralise the French First Army completely at Hannut, despite inflicting significant casualties. The French forces successfully delayed the German advance while allowing the First Army to situate itself at Gembloux, where, a couple of days later, the German advance lost over a third of its armor in combat.

The French once again scored tactical successes at the Battle of Gembloux from 14–15 May. In the aftermath of that battle, although seriously damaged, the First Army was able to retreat to Lille, where it delayed the Germans in the Siege of Lille and was instrumental in the re-embarkation of the British Expeditionary Force, French and Belgian troops at the Evacuation of Dunkirk.

The Allied supreme commander General Maurice Gamelin committed his First Army Group, under General Gaston Billotte, and its strongest Army, the French 1st Army under General Georges Blanchard with the fully mechanised Corps de Cavalerie (Cavalry Corps), commanded by General René Prioux, to advance into Belgium to support the large but more lightly equipped Belgian Army. Gamelin expected the German attack to break the Belgian defences at the Albert Canal line rapidly—the Belgians had in any case indicated they would after four days withdraw to the planned allied front in central Belgium, the "Dyle Line" between Antwerp and Namur—and sought to quickly establish an entrenched front line centred on Gembloux, just north of Namur, to check what Gamelin foresaw as the main enemy effort (Schwerpunkt) of the campaign: an attempt to break through the "Gembloux Gap" between the rivers Dyle and Meuse with a concentration of armoured forces. As Belgium, the Netherlands, and Luxembourg would remain neutral until the German invasion of those countries (Fall Gelb), it had proven impossible to adequately prepare positions for the French 1st Army. Therefore, the Cavalry Corps was given the mission to execute a delaying battle, somewhere between Gembloux and Maastricht (the likely crossing-point, where the Albert Canal connected to it, over the eastern bend of the Meuse), to prevent the enemy from reaching the Gembloux area until the eighth day of an invasion and to allow the 1st Army sufficient time to dig in.

The Cavalry Corps had been created on 26 December 1939, containing both then existing armoured divisions of the Cavalry, the 1re Division Légère Mécanique ("1st Mechanised Light Division") and the 2e DLM. On 26 March 1940 however, 1st DLM was given the mission, in case of an invasion, to establish a connection with the Dutch Army near Breda; this experienced active division was therefore removed from the Cavalry Corps. It was replaced by the 3e DLM, recently constituted on 1 February, manned with reservists and still insufficiently trained. Nevertheless, Prioux still considered his forces sufficient to either contest a river-crossing at Maastricht, or wage a manoeuvre battle or, as a third alternative, defend an improvised line. He was at liberty to choose any option, provided the enemy was kept from Gembloux long enough. He decided to keep all possibilities open and act as the situation would demand.

The German plan for this sector called for an assault by airborne and shock troops to take Fort Eben-Emael and the Meuse and Albert Canal bridges, thus opening a way through the Dutch and Belgian defences for the 4. Panzerdivision (4th Panzer Division), and bring the Albert Canal defensive line to a premature collapse. Once this breach was made, General Erich Hoepner's XVI Army Corps, and Army Group B would assume control of the 4th Panzer Division, the 3rd Panzer Division and the 20th Infantry Division. Hoepner's mission was to quickly launch his Corps from the bridgehead, seize the area around Gembloux before the French infantry divisions could entrench themselves there, and by thus conforming to the worst fears of the French High Command draw all modern Allied forces and their reserves to the north, away from the main thrust through the Ardennes. This would enable the German Army to cut the French First Army, the BEF and the Belgians off by a swift advance to the English Channel leading to a giant encirclement. The action was basically a feint to tie down the Allies in the north so they could not interfere with the main thrust through the Ardennes.

The Battle of Hannut became the largest tank battle of the campaign. The French DLMs had two Brigades Légères Mécaniques each.