The original invasion plan was an awkward compromise devised by General Franz Halder, the chief of staff of Oberkommando des Heeres (OKH, Army High Command) that satisfied no one.

In the final version of the plan, the main effort of the German invasion was made against the Ardennes, the weakest part of the Allied line, where the defence was left to second-rate French divisions in the Second Army and the Ninth Army, on the assumption that the difficulty of moving masses of men and equipment would give the French plenty of time to send reinforcements if the area was attacked.

The Manstein plan has often been called Operation Sichelschnitt, a transliteration of "sickle cut", a catchy expression used after the events by Winston Churchill.

Lieutenant General Erich von Manstein dissented from the 1939 versions of Fall Gelb (Case Yellow), a plan for an invasion of France and the Low Countries, devised by Franz Halder.

Manstein first thought to follow annihilation theory (Vernichtungsgedanke), envisaging a swing from Sedan to the north, rapidly to destroy the Allied armies in a cauldron battle (Kesselschlacht).

Guderian managed to convince him that the danger of a French counter-offensive from the south could be averted by a simultaneous secondary spoiling offensive southwards, in the general direction of Reims.

[3] When Manstein first presented his ideas to OKH, he did not mention Guderian and made the attack to the north the main effort, with a few armoured divisions protecting the left flank of the manoeuvre.

Having found the Halder plan unsatisfactory from the start, Hitler ordered a change of strategy on 13 February in accordance with Manstein's thinking, after having heard only a rough outline.

[1][a] The new plan conformed to Manstein's thinking in that Army Group A would provide the main thrust of the invasion through the Ardennes in southern Belgium.

[6] The revision was a substantial change in emphasis, in which Halder no longer envisaged a simultaneous secondary attack to the west but made it the main effort (Schwerpunkt).

Blitzkrieg theory would have been reflected in the organisation and equipment of the army and Luftwaffe and would have been radically different from those of France, Britain and the Soviet Union, except for the contributions of individuals like Mikhail Tukhachevsky, Charles de Gaulle, Fuller and Liddell Hart.

[12] In the latter hypothesis, favoured by Robert A. Doughty and Karl-Heinz Frieser, the Manstein plan was a return to the principles of 19th century Bewegungskrieg (war of manoeuvre), adapted to modern technology by a sudden and unexpected departure from established German thinking, through the Blitzkrieg elements provided and executed by Guderian.

The influence of Fuller and Liddell Hart in Germany was limited and exaggerated by them after the war; no explicit Blitzkrieg doctrine can be found in pre-war German army records.

The hypothesis allows for a gradual adoption during the thirties of technologically-advanced military equipment and integration into existing Bewegungskrieg thought, familiar to all the great powers prior to 1940, differences being variations on a theme.

[13] Guderian presented the situation in his postwar book Erinnerungen eines Soldaten (Memories of a Soldier 1950, published in English as Panzer Leader) according to the second hypothesis, posing as a lone voice against the reactionary German officer corps.

[18] The Channel coast was a natural obstacle, only a few hundred kilometres from the German border and over such a distance, motorised supply from railheads over the dense west European road network was possible.

The Germans could live off the land, amidst the highly developed agriculture of western Europe, unlike in Poland where it had been much harder to maintain momentum.

The German army managed to concentrate a hugely powerful force at the decisive point but took a gamble of great magnitude that could not be repeated if the attack failed.

[20] In the 2014 edition of Breaking Point, Doughty described how in a 1956 publication, Fuller wrote that the Battle of Sedan was an "attack by paralyzation" that he had devised in 1918 and incorporated into Plan 1919.

[21] Doughty wrote that Fuller had called the advanced forces of the German army an armoured battering-ram, covered by Luftwaffe fighters and dive-bombers acting as flying field artillery, to break through a continuous front at several points.

Fuller's writing was in the vein of much of the early reports of the Battle of France but since then new studies had added nuance, dwelling on the complications and chaos of the military operations.

The Manstein plan led to much more than a simple tank rush through the Ardennes and the fields of northern France; the toughness and training of the German infantry should be recognised, along with the efforts of the engineers and artillery, which got the XIX Panzer Corps across the Meuse.