Germany invaded France, Belgium, Luxembourg, and the Netherlands on 10 May 1940. The main effort was a surprise attack through the supposedly impassable Ardennes Forest, and the panzer divisions of Field Marshal Von Rundstedt’s Army Group A arrived at Meuse River at Sedan in just three days. Though surprised at the unexpected thrust, French theatre commander General Maurice Gamelin confidently thought they could be held at the river. He expected them to wait for the infantry, artillery, and the heavy bridging equipment still moving through the forest before they treid a crossing. Consequently, Gamelin sent artillery to the Meuse in preparation for a defense along the river. The concentrations were quickly destroyed by Stuka dive bombers, or overrun by aggressive German probes. Gamelin was not prepared for the German armor to cross the Meuse. With infantry and reconnaissance units assaulting the far side in rubber boats, Rundstedt’s panzer divisions seized bridges that the British and French air forces did not destroy. His panzers crossed the last natural obstacle before the excellent tank country of the French central plain.
The German breakthrough at Sedan threatened to outflank both of the main Allied defensive positions along the Maginot Line to the south and the Dyle River to the north. The main French armies and the British Expeditionary Force had advanced into Belgium to meet Germany’s Army Group B, and Rundstedt’s breakthrough found them out of position to meet Germany’s main effort. In response, French Prime Minister Paul Reynaud exclaimed “We are lost!” The new British Prime Minister, Winston Churchill, who took over after Neville Chamberlain stepped down due to the invasion, spent much of his precious first few days convincing the French to continue the fight.
As shocking as the breakthrough at Sedan was, it lacked the infantry support (whom were still marching through the forest) to defend the vulnerable bridgeheads. Nevertheless, the panzers’ leader Heinz Guderian (pun intended) ignored orders to hold fast and conducted an overly large “reconnaissance in force” to “secure the bridgeheads”. This he did on 14 May, and extended the penetration 40 miles. But his superior was worried about French armored divisions to the north, and rightly so. (Yes, the French had armored divisions). Guderian’s tanks were vulnerable to counterattack without accompanying infantry, artillery, and heavier anti-tank guns.
On 14 May 1940, the French Cavalry Corps struck the German 3rd and 4th Panzer Divisions in the Gembloux Gap just north of the breakthrough at Dinant and Sedan in the first large scale armored battle in West. The German Panzer Is, IIs, IIIEs, 35ts, 38ts, and IVBs were consistently out fought by the French S35s, R35s, H39s and especially the Char B1 bis. Only massive air support from dive bombing Stukas prevented the complete destruction of both panzer divisions. From Gembloux, Guderian’s bridgeheads lay vulnerable and had the FCC been reinforced, the breakthrough would have almost assuredly been pinched off. Instead, Gamelin, like PM Reynaud, was overcome by events and ordered the FCC to retreat. To add insult to injury, he dispersed the FCC amongst the infantry divisions, and thus ended any possibility of halting the Germans at the Meuse.
Further north, the Dutch leadership was also having a crisis of confidence. Due to the Dutch penchant for opening the dikes, flooding the low lands and turning the country into an island called “Fortress Holland” in the event of an invasion; the Germans planned on seizing the country from the air and holding it until the road bound infantry could arrive. Unfortunately for them the Dutch were prepared for this. A spy in the Abwehr, German intelligence, had informed the Dutch of the impending invasion. The German paratroops made some initial successes, but most were wiped out. The Luftwaffe destroyed the small Dutch air force but paid dearly for it, taking 40% casualties in the process. Furthermore Dutch anti-aircraft defenses were extensive and modern, and nearly 3/4s of the German transport fleet was shot down. The Luftwaffe and the Wehrmacht in the north didn’t just get a bloody nose, it was on life support.
By 14 May, the same day the French Cavalry Corps defeated the German panzers, the fight for the Netherlands had reached its climax, and the Dutch were winning. The campaign, supposed to only be a diversion for the fighting further south, was much more difficult than expected. The Germans were desperate and the only uncommitted forces were the Luftwaffe’s medium range bombers. Like Guernica and Warsaw before it, the Germans bombed Rotterdam hoping to destroy their enemy’s will to fight. Unlike, Guernica and Warsaw, this time it worked: Rotterdam was flattened and fearing for their safety, the Dutch royal family fled the country that night. The Dutch High Command surrendered the country the next day. Most of the Dutch Army had yet to fire a round.
Unlike the Dutch, the Belgians, French, and British failed to inflict serious losses on the Luftwaffe. Soon the Stuka sirens broke up any counter attacks and struck terror into the retreating Allied commands. Luftwaffe bombers were seemingly everywhere, and though the Allied air forces outnumbered the Luftwaffe, they were nowhere to be found. They were destroyed on the ground, wasted away or their airfields were overrun. The massive Belgian fortress at Eben Emael was the centerpiece of their defense and fell to creative airborne and glide assault, one of the few German airborne successes in the war. The best Allied troops were fighting on the Dyle River in Belgium and on the Maginot line in the south, and there was nothing left to defeat the German breakthrough in the center. The French high command was paralyzed.
On 15 May, Reynaud phoned Churchill to say the war was lost, and Churchill, in spite of the French historical inclination to do so and still survive, believed him. The next day, the German panzers sprinted out of the bridgeheads and caused even more chaos to Allied command and control. Soon after, Churchill ordered the British Expeditionary Force, which had hardly engaged any Germans so far in the war, to retreat to Dunkirk, and the Belgian Army to the north was cut off.
The Germans defeated the Allies in just six days. They did it by defeating the Allied leadership not the Allied armies. Most of the French, British, Belgian, and Dutch troops hadn’t even fired their weapons yet. The Battle for France and the Low Countries lasted another 40 days through the sheer force of will of what was left of the French Army.