"Wilhelm Flicke worked in German cryptologic organizations, as an analyst and administrator, from World War I through World War II. The rights to his Kriegsgeheimnisse in Aether, which covers both wars, was purchased by the U.S. Government shortly after World War II. The following is his account of radio intelligence intercept of the West.
The campaign in the West in the summer of 1940 appears too many people to be the master stroke of a military genius. Even when we take into account the German superiority in numbers and materiel and appraise adequately the spirit of the German troops, many things still remain inexplicable – in particular the swift drive through the northern continuation of the Maginot Line. On the basis of what I was able to learn, I shall attempt to throw a few side lights on this campaign, without pretending to be able to explain everything.
I have already reported on the situation in the intercept service. Conditions for successful intercept work were as favorable as one could desire in France, Holland, and Belgium".