The reckoning of a campaign

In six weeks, from 10 May to the end of June 1940, Germany had defeated the Netherlands, Belgium, Luxembourg and France and driven the British Expeditionary Force from the continent — a reversal that few had believed possible. The contrast with the stalemate of 1914–1918 struck the imagination.

To understand this victory, several factors intertwined, and you can debate their relative importance. German material superiority was in fact a myth: the Allies fielded as many, if not more, tanks (often better ones) and men. The difference lay above all in doctrine (concentration of armour, tank-aircraft-radio cooperation, the initiative of commanders), in the audacious plan (the breakthrough through the Ardennes), in command of the air, and in the failings of the Allied command (dispersal of tanks, rigidity, slowness of decisions, poor inter-Allied coordination).

How is the Allied defeat of 1940 to be explained, in essence? By material inferiority? By errors of doctrine and command? Or by the German plan and command of the air? The diagnosis shapes the reading of the entire campaign.