The invasion of the Low Countries and France

France’s 800,000-man standing army was thought at the time to be the most powerful in Europe. But the French had not progressed beyond the defensive mentality inherited from World War I, and they relied primarily on their Maginot Line for protection against a German offensive. The Maginot Line was an extremely well-developed chain of fortifications running from the Swiss frontier opposite Basel northward along the left bank of the Rhine and then northwestward no farther than Montmédy, near the Belgian frontier south of the Ardennes Forest. The line consisted of a series of giant pillboxes and other defensive installations constructed in depth, equipped with underground supply and communications facilities, and connected by rail lines, with all its heavy guns pointed east at the German frontier. Depending heavily on the line as a defense against German attack, the French had 41 divisions manning it or backing it, whereas only 39 divisions were watching the long stretch of frontier north of it, from Montmédy through the Ardennes and across Flanders to the English Channel.

In their plan for the invasion of France and the Low Countries, the Germans kept General Wilhelm von Leeb’s Army Group C facing the Maginot Line so as to deter the French from diverting forces from it, while launching Bock’s Army Group B into the basin of the Lower Maas River north of Liège and Rundstedt’s Army Group A into the Ardennes. Army Group B comprised Küchler’s 18th Army, with one armoured division and airborne support, to attack the Netherlands, and Reichenau’s 6th, with two armoured divisions, to advance over the Belgian plain. These two armies would have to deal not only with the Dutch and Belgian armies but also with the forces that the Allies, according to their plan, would send into the Low Countries, namely two French armies and nine British divisions. Rundstedt’s Army Group A, however, was much stronger, comprising as it did Kluge’s 4th Army, List’s 12th, and General Ernst Busch’s 16th, with General Maximilian von Weichs’s 2nd in reserve, besides a large armoured group under Paul Ludwig von Kleist and a smaller one under General Hermann Hoth, and amounting in all to 44 divisions, seven of them armoured, with 27 divisions in reserve. Army Group A thus amounted to more than 1,500,000 men and more than 1,500 tanks, and it would strike at the weak hinge of the Allies’ wheel into Belgium—that is to say, at two French armies, General Charles Huntziger’s 2nd and General André Corap’s 9th, which together mustered only 12 infantry and four horsed cavalry divisions and stood, respectively, east and west of Sedan on the least-fortified stretch of the French frontier. Against this weak centre of the Allied line were thus massed nearly two-thirds of Germany’s forces in the west and nearly three-quarters of its tank forces.

The Dutch Army comprised 10 divisions and the equivalent of 10 more in smaller formations, and thus totaled more than 400,000 men. It apparently had a good chance of withstanding the German invasion, since the attacking German army comprised only seven divisions, apart from the airborne forces it would use. The Dutch, however, had a wide front, a very sensitive and loosely settled rear, very few tanks, and no experience of modern warfare. On May 10, the German attack on the Netherlands began with the capture by parachutists of the bridges at Moerdijk, at Dordrecht, and at Rotterdam and with landings on the airfields around The Hague. On the same day, the weakly held Peel Line, south of the westward-turning arc of the Maas, was penetrated by the German land forces; and on May 11 the Dutch defenders fell back westward past Tilburg to Breda, with the consequence that the French 7th Army, under General Henri Giraud, whose leading forces had sped forward across Belgium over the 140 miles to Tilburg, fell back to Breda likewise. The German tanks thus had a clear road to Moerdijk, and by noon on May 12 they were in the outskirts of Rotterdam. North of the Maas, meanwhile, where the bulk of the Dutch defense was concentrated, the Germans achieved a narrow breach of the Geld Valley line on May 12, whereupon the Dutch, unable to counterattack, retreated to the “Fortress of Holland” Line protecting Utrecht and Amsterdam. Queen Wilhelmina and her government left the country for England on May 13; and the next day the Dutch commander in chief, General Henri Gerard Winkelman, surrendered to the Germans, who had threatened to bomb Rotterdam and Utrecht, as places in the front line of the fighting, if resistance continued. In fact, Rotterdam was bombed, after the capitulation, by 30 planes through a mistake in the Germans’ signal communications.

The news of the German onslaught in the Low Countries, dismaying as it was to the Allies, had one effect that was to be of momentous importance to their fortunes: Chamberlain, whose halfhearted conduct of the war had been bitterly criticized in the House of Commons during the debate of May 7–8 on the campaign in Norway, resigned office in the evening of May 10 and was succeeded as prime minister by Churchill, who formed a coalition government.

For the first phase of the invasion of the Belgian plain north of Liège, Reichenau had four army corps, one armoured corps, and only 500 airborne troops; but he also had massive cooperation from the German Luftwaffe, whose dive bombers and fighters played a major role in breaking down the Belgian defenses. West of the Maastricht “appendix” of indefensible Dutch territory separating Belgium from Germany, the fortress of Eben Emael, immediately opposite Maastricht, and the line of the Albert Canal constituted the Belgians’ foremost defensive position. On May 10 German airborne troops landed in gliders on the top of the fortress and on bridges over the canal. On May 11 the Belgian front was broken, the German tanks running on westward and some of the infantry turning southward to take Liège from the rear, while the Belgians made a general retreat to the Antwerp–Namur, or Dyle, Line. French and British divisions had just arrived on this Dyle Line, and General René Prioux’s two tank divisions went out from it to challenge the German advance. After a big battle on May 14, however, Prioux’s tanks had to retire to the consolidated Dyle Line; and on May 15, notwithstanding a successful defense against a German attack, Gamelin ordered the abandonment of the position, because events farther to the south had made it strategically untenable.

The chances for success of the German offensive against France hinged on a German advance through the hilly and dense Ardennes Forest, which the French considered to be impassable to tanks. But the Germans did succeed in moving their tank columns through that difficult belt of country by means of an amazing feat of staff work. While the armoured divisions used such roads through the forest as were available, infantry divisions started alongside them by using field and woodland paths and marched so fast across country that the leading ones reached the Meuse River only a day after the armoured divisions had.

The decisive operations in France were those of Rundstedt’s Army Group A. Kleist’s tanks on May 10 took only three hours to cover the 30 miles from the eastern border of independent Luxembourg to the southeastern border of Belgium; and on May 11 the French cavalry divisions that had ridden forward into the Ardennes to oppose them were thrown back over the Semois River. By the evening of May 12 the Germans were across the Franco-Belgian frontier and overlooking the Meuse River. The defenses of this sector were rudimentary, and it was the least-fortified stretch of the whole French front. Worse still, the defending French 2nd and 9th armies had hardly any antitank guns or antiaircraft artillery with which to slow down the German armoured columns and shoot down their dive bombers. Such was the folly of the French belief that a German armoured thrust through the Ardennes was unlikely.

On May 13 Kleist’s forces achieved a threefold crossing of the Meuse River. At Sedan wave after wave of German dive bombers swooped on the French defenders of the south bank. The latter could not stand the nerve-racking strain, and the German troops were able to push across the river in rubber boats and on rafts. The tremendous air bombardment was the decisive factor in the crossings. A thousand aircraft supported Kleist’s forces, while only a few French aircraft intervened in a gallant but hopeless effort to aid their troops on the ground. Next day, after the tanks had been brought across, Guderian widened the Sedan bridgehead and beat off French counterattacks. On May 15 he broke through the French defenses into open country, turning westward in the direction of the English Channel. On May 16 his forces swept on west for nearly 50 miles. His superiors tried to put on the brake, feeling that such rapid progress was hazardous, but the pace of the German drive upset the French far more, and their collapse spread as Reinhardt’s corps joined in the pressure. When more German tanks crossed the Meuse between Givet and Namur, the breach of the French front was 60 miles wide.

Driving westward down the empty corridor between the Sambre and the Aisne rivers, Guderian’s tanks crossed the Oise River on May 17 and reached Amiens two days later. Giraud, who on May 15 had superseded Corap in command of the French 9th Army, was thus frustrated in his desperate plan of checking the Germans on the Oise; and Kleist, meanwhile, by lining the Aisne progressively with tanks until the infantry came up to relieve them, was protecting the southwestern flank of the advance against the danger of a counteroffensive from the south. Indeed, when the Germans, on May 15, were reported to be crossing the Aisne River between Rethel and Laon, Gamelin told Reynaud that he had no reserves in that sector and that Paris might fall within two days’ time. Thereupon Reynaud, though he postponed his immediate decision to move the government to Tours, summoned General Maxime Weygand from Syria to take Gamelin’s place as commander in chief; but Weygand did not arrive until May 19.

Guderian’s tanks were at Abbeville on May 20, and on May 22 he turned northward to threaten Calais and Dunkirk, while Reinhardt, swinging south of the British rear at Arras, headed for the same objectives, the remaining ports by which the British Expeditionary Force (BEF) could be evacuated.