The Manstein Plan

On 31 October 1939, in Koblenz on the Rhine, where the headquarters of the German Army Group A had been installed for a few days, its commander, Colonel General Gerd von Rundstedt, signed two letters to the Commander-in-Chief of the Army, Colonel General Walther von Brauchitsch. Their author was Army Group A’s chief of staff, Lieutenant General Erich von Manstein. The first argued that the planned offensive in the west could not bring a decision in the war. The second criticised in detail Case Yellow (Fall Gelb), the plan issued by the Army High Command (OKH) two days earlier, and demanded that the main effort be moved from the northern to the southern wing – that is, to Army Group A, facing the Belgian Ardennes and Luxembourg. It was the first of a series of memoranda from which, over the following months, there grew the plan later known as the Manstein Plan, and dubbed by Winston Churchill the “sickle cut” (in German, Sichelschnitt).

It is often said that on 31 October Manstein proposed an attack through the Ardennes instead of through Belgium, where the offensive was expected. The date is right, but the substance needs two qualifications. The Ardennes lie mostly in Belgium and Luxembourg, so the dispute was not about whether to go through Belgium, but about whether the main blow should pass across the plains of central Belgium or through the wooded hills of its south. Secondly, the first memorandum did not yet contain a fully formed concept of a tank thrust through the Ardennes to Sedan and on to the English Channel. Above all it demanded that the weight of the attack be shifted south and that the Allies be cut off from the river Somme. The bold armoured drive with which the Manstein Plan is associated today took shape in the following weeks, with the involvement of Heinz Guderian, and in those same days Hitler too had the idea of striking at Sedan.

Army Group A

Manstein and Rundstedt came to the west straight from Poland. In the summer of 1939, as commander and chief of staff, they had prepared the southern part of Case White, and in September they directed Army Group South, which delivered the main blow in the September Campaign and destroyed the Polish armies in the Battle of the Bzura. At the beginning of October Rundstedt was for not quite three weeks commander of the forces in the occupied east, and at the end of the month his staff, renamed Army Group A, moved to Koblenz, opposite the Luxembourg and Belgian borders. The staff included the operations officer, Günther Blumentritt, and Major Henning von Tresckow, later one of the leaders of the military opposition.

In Koblenz Manstein became acquainted with Case Yellow. On 9 October Adolf Hitler, in Directive No. 6, had ordered the preparation of an offensive through Luxembourg, Belgium and the Netherlands, and on 19 October the OKH, in practice directed by the Chief of the General Staff, General Franz Halder, issued the first version of the plan. Under pressure from Hitler a second version appeared on 29 October. According to this, the main blow was to be delivered by Colonel General Fedor von Bock’s Army Group B, advancing through central Belgium north and south of Liège. According to the British official history of the campaign, Bock was to receive 43 divisions, including nine armoured and four motorised. Rundstedt had 22 infantry divisions without tanks and the task of covering Bock’s left flank. Colonel General Wilhelm von Leeb’s Army Group C was to feign an attack on the Maginot Line, and 19 divisions were held in reserve.

What the memorandum contained

Manstein considered the plan fundamentally misconceived. It reminded him of the Schlieffen Plan of 1914, only without its sweep: a strong right wing was to advance through Belgium, strike head-on at the French and British forces that would certainly enter Belgium to meet it, and push them back towards the Somme. This was exactly the kind of attack the Allies expected. Even if it succeeded, the Germans would take the Belgian coast and part of northern France, but would not destroy the enemy’s armies. The front would come to a halt on the Somme, and the war would turn into a long war of position which Germany, poor in raw materials and cut off by blockade, could not win.

The first of the letters of 31 October stated this assessment plainly: the operation in its planned form could have no decisive effect on the war, so it would be better to let the Allies strike first. The second, more important letter contained the line of reasoning that Manstein then developed over three months. The success of the campaign depended on destroying all the enemy forces north of the Somme. They had to be cut off from the Somme, not pushed towards it by a frontal blow. For this reason, he wrote, the main effort of the whole operation must lie on the southern wing. There, in Army Group A’s sector, lay both the greatest danger and the chance of a great success. A thrust westwards from southern Belgium and Luxembourg, across the Meuse in the Sedan area, towards the lower Somme, could reach the rear of the Allied forces that would move into Belgium. For this Army Group A needed an additional army and mobile units. At the same time it would have to cover its southern flank against a French counter-attack.

In its original form Manstein’s concept was still fairly traditional. Historians, among them Karl-Heinz Frieser, author of the most important study of the 1940 campaign, point out that Manstein first envisaged a wheel to the north after crossing the Meuse and a great battle of encirclement, in the spirit of the German school of the “battle of annihilation”. Only in November, when he asked Guderian, commander of XIX Army Corps, whether tanks could get through the Ardennes, did Guderian not only confirm that they could, but propose that the armoured divisions should not halt after breaking through the front, but race westwards to the coast without waiting for the infantry.

The OKH resists

Brauchitsch and Halder received the memorandum coolly. On 3 November Brauchitsch came to Koblenz and spoke with Rundstedt and Manstein. He rejected their proposals and promised only to give Army Group A one armoured division. Personal antipathy compounded the dispute over the plan. At the beginning of 1938 Manstein, then Deputy Chief of the General Staff, had been regarded as the successor to General Ludwig Beck. During the Blomberg–Fritsch affair he was sent off to command a division, and it was Halder who succeeded Beck as Chief of Staff. Halder regarded the memoranda from Koblenz as an attempt by an ambitious rival, who wanted the leading role in the campaign for his own army group, to undermine his plan. The OKH also had objective reasons. Only a few narrow, winding roads led through the Ardennes, and columns of tanks and vehicles would have had to crawl along them for many days. Had the Allied air forces spotted and bombed them, the thrust would have ended in catastrophe and Germany would have lost most of its armour.

Hitler knew nothing of Manstein’s memoranda at the time, but he was looking for a similar solution himself. As early as 25 October he had told Brauchitsch and Halder that he would prefer to strike south of Liège, and on 30 October, the day before the first memorandum, according to the diary of General Alfred Jodl he proposed sending an armoured group via Arlon towards Sedan. On 11 November, on his instructions, the OKH ordered the formation of a third group of mobile troops on the southern wing, and in the version of the plan of 15 November Army Group A received Guderian’s corps with two armoured divisions. Its task was to seize the west bank of the Meuse at Sedan by surprise. This did not, however, change the essence of the plan: the main blow was still to be delivered by Bock.

Manstein did not give way. Further memoranda, signed by Rundstedt or sent directly to Halder, followed on 21 and 30 November, 6 and 18 December 1939 and 12 January 1940. Each was more radical than the last. Brauchitsch refused to pass them on to Hitler, explaining that the decision on the direction of the main blow belonged to the Führer, who would take it on the basis of his own recommendations.

From Mechelen to the Reich Chancellery

Chance changed the situation. On 10 January 1940 a German liaison aircraft lost its way in fog and made a forced landing in Belgium. Its passenger, a Luftwaffe major, was carrying documents with the plan of attack, which he failed to burn (the Mechelen incident). The Belgians passed their contents to the French and British, and Berlin had to reckon with the plan being known to the enemy. In those same days Halder rid himself of his troublesome rival. On 27 January Manstein was appointed commander of XXXVIII Army Corps, then being formed in Stettin (Szczecin), far from the western front. Formally this was a promotion; in practice it removed him from planning.

Tresckow and Blumentritt, however, resolved that the idea should not be lost. When Hitler’s chief adjutant, Rudolf Schmundt, a friend of Tresckow’s, came to Koblenz, they laid Manstein’s concept before him. On 2 February Schmundt reported it to Hitler, who recognised in it his own thoughts. In February the OKH held war games which showed that an attack on Sedan required far greater forces, and on 13 February, according to Jodl’s diary, Hitler announced that the armoured divisions should be concentrated in the direction of Sedan, where the enemy did not expect the main blow. On 17 February Manstein came to the Reich Chancellery with other newly appointed corps commanders for breakfast with Hitler. After the meal Hitler invited him into his study and heard out his argument. Manstein wrote after the war that Hitler had grasped with astonishing speed the arguments that Army Group A had been defending for months. Hitler is said to have remarked of him that he was an exceptionally able man, but that he did not trust him.

On 24 February 1940 the OKH issued the fourth version of Case Yellow. The main blow was to be delivered by Army Group A through the Ardennes, while Army Group B, attacking the Netherlands and central Belgium, was to draw the Allied forces there. Halder, who had earlier fought the idea, now worked it out carefully and developed it, though more cautiously than Manstein wanted: the river was to be forced by infantry, and the armoured divisions were to advance together with it. Manstein himself no longer had any influence on the further work.

The other side

The plan struck at the Allies’ weakest point. The French Commander-in-Chief, General Maurice Gamelin, assumed that the Germans, as in 1914, would attack across the plains of Belgium. In November 1939 the Dyle Plan was adopted: once the Germans entered Belgium, the best French armies and the British Expeditionary Force were to advance to the line of the river Dyle, and in March 1940 Gamelin also sent the Seventh Army as far as Breda in the Netherlands. The Ardennes were considered difficult terrain for large armoured formations, and it was believed that in the event of an attack the French would have enough time to bring up reinforcements. The sector facing the Ardennes was therefore held by the weak Second and Ninth Armies, made up largely of reserve divisions. Belgium, which held to its neutrality, allowed neither joint planning nor Allied troops on its territory.

Its place in the war

On 10 May 1940 the Wehrmacht attacked the Netherlands, Belgium and Luxembourg. The Allies advanced into Belgium as planned, while General Ewald von Kleist’s armoured group passed through the Ardennes with five armoured divisions, three of them from Guderian’s corps, and on its right flank a corps with two more, including Erwin Rommel’s division. On 13 May the Germans crossed the Meuse at Sedan and at several other points, and on 20 May Guderian’s tanks reached the English Channel near Abbeville. The Allied armies in Belgium were cut off from France, and more than 330,000 soldiers, most of them British, were evacuated to England from Dunkirk. On 22 June France signed an armistice. Polish units re-formed in France also fought in the campaign, and after the defeat some of their soldiers made their way to Britain.

Manstein, whose corps went into action only on 16 May, watched the victory from the second line. Hitler later said that of all the generals with whom he had discussed the plan of attack in the west, only Manstein had understood him. Propaganda attributed the success to the Führer’s genius, and the generals who in the autumn had regarded the offensive as madness lost what remained of their authority with him. After the war Halder maintained that he had been the father of the plan, while historians argue that the victory of 1940 was not the execution of a premeditated doctrine of “Blitzkrieg” but a risky improvisation that succeeded thanks to the enemy’s mistakes. The belief of Hitler and some of his generals that it could be repeated in any conditions weighed heavily on the plan for the attack on the Soviet Union in 1941. The memorandum of 31 October remains one of the best-known military documents of the war: it marked the start of the road to the swiftest defeat of a great power in the twentieth century.