The German invasion, originally set for 12 November 1939, was repeatedly postponed because of bitterly cold weather and pleas from Hitler's generals for additional time to prepare. Then, on 10 January 1940, an event occurred that may have changed history. On that date, the pilot of a German military aircraft flying from Munster to Köln became lost in dense fog and was forced to land near Mechelen-sur-Meuse, Belgium. The passenger, Major Helmut Reinberger, was a staff officer of the 7th Airborne Division and was carrying top-secret operational plans for the German attack in the west. Reinberger was to have traveled by train, but delays led him to fly. Although the two Germans tried to burn the papers, the Belgian police secured the bulk of them. That discovery was only one of several indications of a German plan to strike west that caused neutral Belgium to open military talks with France and Britain. In any case, when Hitler learned that the invasion plan had been compromised, he abandoned it.
The need to recast the plan now caused the German invasion to be delayed until May. Generalmajor Erich von Manstein, assisted by Generalmajors Heinz Guderian and Walther Model, drew up the new plan. Known as sichelschnitt ( the cut of the sickle), the plan was agreed on in a meeting between Hitler and Manstein on 17 February 1940 and became the basis for German planning of the assault in the west ( case yellow). It shifted the major effort from central Belgium to just north of the French defensive system known as the Maginot Line. The northern effort would occur first, drawing the Allies into Belgium. Then the major blow would fall to the south, in the hilly and wooded Ardennes—country reputedly impassable for tanks. The plan called for the invading Germans to cross the Meuse River and crack the French lines at Sedan, then swing northwest to the Channel and cut off the best British and French divisions, which would in the meantime have moved into Belgium.
Colonel General Fedor von Bock's Army Group B, charged with invading Belgium and Holland, was downgraded from 37 divisions in the original plan to only 28 in the Manstein plan, and 3 rather than 8 panzer divisions. Colonel General Gerd von Rundstedt's Army Group A, which was to move through the Ardennes, was upgraded from 17 to 44 divisions, including 7 armor divisions rather than a single armor division. At the point of the breakthrough, the Germans would thus outnumber the defending French 44 divisions to 9.
The original German plan was somewhat similar to the Schlieffen Plan of 1914 and would have followed Allied staff predictions. Its axis of advance would have encountered the best Franco-British forces and might thus have ended in failure. Still, Manstein's plan appeared risky, and although he had Hitler's firm backing, many senior military leaders opposed the plan. Apart from the plan, factors working in Germany's favor were the experiences it had gained in Poland regarding the movement of massed armor and supply columns, its clear superiority in numbers of combat aircraft and antiaircraft guns, and the fact that a single national command system faced four disparate national armies. Thomas J. Weiler and Spencer C. Tucker
Blatt, Joel, ed. The French Defeat of 1940: Reassessments. New York: Berghahn Publishers, 1988.; Chapman, Guy. Why France Collapsed. London: Cassell, 1969.; Horne, Alistair. To Lose a Battle: France 1940. Boston: Little, Brown, 1969.; Liddell Hart, Basil H. The German Generals Talk. New York: William Morrow, 1948.; May, Ernest R. Strange Victory: Hitler's Conquest of France. New York: Hill and Wang, 2000.; Shennan, Andrew. The Fall of France. London: Longmann, 2000.
Thomas J. Weiler and Spencer C. Tucker