German invasion of Belgium (1940)

• 1. Introduction

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  On the 10th of May 1940, Germany invaded three countries simultaneously: Luxembourg, the Netherlands, and Belgium. Within 18 days, the Belgian Army would surrender, the Allied forces that had rushed to defend Belgium would be trapped with their backs to the English Channel, and the entire strategic balance of the war in western Europe would be shattered. The campaign that unfolded in those 18 days is known as the Belgian campaign, and it contained several firsts in the history of warfare: the first large-scale strategic airborne operation ever attempted, and what was, at the time, the largest tank battle in history. But behind the speed and shock of the German advance lay months and years of miscalculation, political caution, and strategic disagreement between the very nations that needed most to cooperate. How did Germany achieve its breakthrough so quickly? Why did the Allied forces, which in some respects outnumbered and outgunned the Germans, end up pinned against the sea? And what role did Belgium's own fraught attempts at neutrality play in sealing its fate?

• 2. Belgium's Impossible Neutrality

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  Marshal Philippe Petain had, as far back as October 1930 and again in January 1933, proposed using Belgium as a springboard for a French strike against Germany's Ruhr area in the event of war. That was precisely what Belgium feared. The Franco-Belgian Accord of 1920, concluded on the 7th of September that year, obligated Belgium to mobilise alongside France under certain conditions, and Belgian leaders were never entirely sure whether a German attack on Poland would trigger those conditions. The Belgians watched the Franco-Soviet pact of May 1935 with alarm, fearing it would drag them into a war on France's terms rather than their own. King Leopold III gave a speech on the 14th of October 1936 before the Council of Ministers arguing for stronger Belgian defences, and that same year Belgium withdrew from the Western Alliance entirely. The British and French publicly declared on the 24th of April 1937 that Belgium's security was paramount and that they would defend its borders, while releasing Belgium from its own Locarno obligations to assist them if Germany attacked Poland. Yet this declaration of support rang hollow to Belgian ears. The remilitarisation of the Rhineland had proceeded without French or British opposition, convincing the Belgian General Staff that neither power would fight for its own strategic interests, let alone Belgium's. Internal politics compounded the problem. The Flemish Movement had grown powerful and was instinctively hostile to French influence. The socialist Paul-Henri Spaak, who came to power in 1935, had to manage a strong pacifist wing in his party. Meanwhile, the Walloons objected fiercely to any strategy that would allow German forces to occupy French-speaking Belgian territory. The result was a Belgian government that refused to hold official staff meetings with French or British military planners, out of fear that any such contact would compromise its declared neutrality, even as the Wehrmacht's strength grew year by year. On the 10th of January 1940, a German Army major named Hellmuth Reinberger crash-landed a Messerschmitt Bf 108 near the Belgian village of Mechelen-aan-de-Maas, carrying the initial German invasion plans. The Belgians suspected a ruse, but the plans were genuine. Belgian intelligence and the military attache in Cologne concluded that Germany would now change its plans entirely, and their analysts predicted a main thrust through the Ardennes to encircle the Allied forces in Belgium. King Leopold and his aide-de-camp General Raoul Van Overstraeten warned the French Army command of their concerns on the 8th of March and again on the 14th of April. They were ignored.

• 3. The Allied Plan and Its Flaw

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  Maurice Gamelin, the French commander, approved the Dyle Plan as the main Allied strategy for defending Belgium. Under it, the best of the Allied forces would advance into central Belgium to the Dyle river the moment Germany invaded. The logic seemed sound: the move would reduce the Allied front in central Belgium by 70 km, freeing reserves, and might absorb some twenty Belgian divisions into a coherent defensive line. The French 7th Army under Henri Giraud was to race north toward Breda in the Netherlands. The British Expeditionary Force under General John Vereker, Lord Gort, would hold the central position along the Brussels-Ghent axis. The French 1st Army, including Rene Prioux's Cavalry Corps with its formidable SOMUA S35 tanks, would cover the so-called Gembloux gap between the Dyle line and Namur to the south. But the plan had a structural weakness that critics saw clearly. By advancing deep into Belgium, the Allies were committing their best forces to a forward position that was vulnerable to being outflanked from the south. The Ardennes region, which lay to the south and east of the Allied advance, was considered by most French planners to be too difficult for a major armoured thrust. Gamelin was willing to accept that risk. What he did not know was that Erich von Manstein had designed precisely such a thrust, and that Army Group A was preparing to drive through the Ardennes with the bulk of German armour. Army Group B, advancing through central Belgium, was a feint. Its role was to draw the Allied armies forward, away from the Sedan area, and then trap them once Army Group A cut through to the English Channel. The Belgians, despite being officially neutral, had secretly shared defence plans, troop dispositions, intelligence, and air reconnaissance arrangements with the French military attache in Brussels. But officially, French forces were not allowed to enter Belgium, even when German invasion plans had been recovered and studied. When the invasion came, the Allied armies would need to sprint into position over open ground, with no prepared defences waiting for them.

• 4. Fort Eben-Emael and the Glider Attack

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  Fort Eben-Emael guarded the northern flank of Liege and stood astride the critical route through which German armour would need to pass if Army Group B was to advance at speed into central Belgium. The fort's gun turrets could lay fire across the three vital bridges over the Albert Canal at Veldwezelt, Vroenhoven, and Kanne. If those bridges were destroyed or the fort's guns remained active, the German 6th Army would be bottled up in the Maastricht enclave and the entire timetable for Fall Gelb would collapse. Adolf Hitler summoned Lieutenant-General Kurt Student of the 7th Air Division to discuss the problem. A conventional parachute drop was rejected: the Junkers Ju 52 transports were too slow and vulnerable to anti-aircraft fire, and a seven-second drop from minimum operational height alone would scatter men over 300 metres. Hitler then posed a question. The fort's top surfaces were flat and unprotected. Could a glider, such as the DFS 230, land on them? Student replied that it could be done, but only by 12 aircraft in daylight, delivering 80-90 men directly onto the fort. Hitler then revealed the weapon that would make the operation viable: the Hohlladungwaffe, a 50 kg hollow-charge explosive capable of penetrating Belgian gun turrets. The assault force was named Sturmabteilung Koch after its commander, Hauptmann Walter Koch, and assembled in November 1939. It was drawn primarily from the 1st Parachute Regiment and engineers of the 7th Air Division, with a small group of Luftwaffe pilots. On the morning of the 10th of May 1940, the gliders landed on top of the fort. Using the hollow-charge explosives and flamethrowers, the Fallschirmjager disabled the defences. Within 24 hours, German infantry had overcome the Belgian defenders of the 7th Infantry Division. The Albert Canal's west bank, which the 4th and 7th Belgian infantry divisions had held for nearly 36 hours, could no longer be sustained. German infantry of the 18th Army poured through. German soldiers had already established bridgeheads across the canal before British forces could reach it some 48 hours later.

• 5. The Tank Battle at Hannut

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  Hoepner's XVI Panzer-Motorized Corps, containing the 3rd and 4th Panzer divisions, launched its offensive toward the Gembloux gap beginning on the 12th of May. The gap stretched between Wavre in the north and Namur in the south, a flat, unfortified space 20 to 30 km wide with no natural obstacles. General Rene Prioux's Cavalry Corps moved 30 km east of the main French line to screen it, buying time for the French 1st Army to dig in. The clash between Hoepner and Prioux near Hannut on the 12th of May became the largest tank battle in history at the time, though it would later be surpassed by engagements in North Africa and on the Eastern Front. Despite frequent claims to the contrary, the Germans did not outnumber the French in tanks that could actually fight a tank-vs-tank engagement. The German 3rd and 4th Panzer divisions numbered 280 and 343 tanks respectively, but the effective fighting strength was dominated by Panzer Is and Panzer IIs, which had armour of just 7 to 13 mm. Virtually every French weapon from the 25 mm calibre upward could penetrate them. The French had 176 SOMUA S35s and 239 Hotchkiss H35 tanks; both types were superior to most German armour in protection and firepower. The French also fielded 90 Panhard 178 armoured cars whose 25 mm main gun could punch through a Panzer IV. On the first day, Prioux's tanks came off best. The battlefield around Hannut was littered with knocked-out German Panzers, the bulk of them Panzer Is and IIs. One account preserved in the historical record describes a German Panzer commander climbing onto a Hotchkiss H-35 with a hammer, apparently intending to smash its periscopes, before falling off and being crushed by the tank's tracks. The French disabled 160 German tanks on 12 and the 13th of May while losing 105 of their own. But tactical success dissolved into operational failure. On the 13th of May, the French strung their armour out in a thin line between Hannut and Huy with no depth and no reserves for a counterattack. Hoepner concentrated against the 3rd Light Mechanized Division, achieved a local breakthrough, and the entire position had to be abandoned. The Germans repaired roughly three-quarters of their disabled tanks. Only 49 were destroyed outright, while 111 were recovered. By the 16th of May, the 4th Panzer Division had been reduced to 137 tanks, including just four Panzer IVs. Its losses were heavy, but so were the French, and the French 1st Army was now forced to retreat south, leaving its own tanks on the battlefield while the Germans recovered theirs.

• 6. The Collapse and Dunkirk

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  On the morning of the 15th of May, Army Group A broke the defences at Sedan and drove for the English Channel. German armour reached the Channel after five days, completing the encirclement of the Allied armies in Belgium. The withdrawal from Belgium was staged across three nights: from the 16th to the 17th of May to the River Senne, then to the Dendre, then to the Scheldt. The Belgian Army fought rearguard actions through this retreat; the 2nd Regiment of Guides and the 2nd Carabineers Cyclists of the 2nd Belgian Cavalry Division were particularly distinguished at the Battles of Tirlemont and Halen. Brussels fell to German forces on the 17th of May. Four Belgian infantry divisions, including the 13th and 17th reserve infantry divisions, delayed the German Eighteenth Army at Antwerp. The city fell on the 18th or the 19th of May after considerable Belgian resistance. A series of Belgian forts at Namur fell in sequence: Fort Marchovelette on the 18th of May, Suarlee on the 19th, St. Heribert and Malonne on the 21st, Dave, Maizeret, and Andoy on the 23rd. General Gort discovered that the French had neither plan nor reserves to stop the German armoured advance. He feared German armour might appear on the Allied right flank and cut off the Channel ports at Calais and Boulogne. The War Cabinet in London rejected a proposal for a strategic British withdrawal and ordered Gort to attack south-west through all opposition. The Belgian Army was asked to conform or face being evacuated by the Royal Navy. The Belgian Army surrendered on the 28th of May 1940. On the 17th of May, the Belgian fishing fleet, totalling 507 vessels, had been ordered to help evacuate troops from the Belgian coast. Most of the Belgian merchant fleet, some 100 ships totalling 358,000 tons, evaded German capture; placed under British control under a Belgian-Royal Navy agreement, those ships and their 3,350 crewmen suffered heavy losses, with only 28,000 tons of the original tonnage surviving to the end of the war. The British Royal Navy's Operation Dynamo evacuated the British Expeditionary Force along with many Belgian and French soldiers from the Belgian ports, allowing them to continue fighting. France reached its own armistice with Germany in June 1940. Belgium remained under German occupation until the late summer and autumn of 1944, when the Western Allies liberated it.