On the 11th and 12th of February 1942, the German ships Scharnhorst, Gneisenau, Prinz Eugen, and their escorts escaped the port of Brest, steamed through the English Channel, and returned to Germany. Sometimes dubbed the “Channel Dash,” the event was a major surprise to the British, who depended in part on their coastal radar to detect just such an operation. Dr. Jones relates in Most Secret War how the Germans conditioned the British radar operators to accept heightened levels of jamming.
… on the morning of 11th February Colonel Wallace … called to see me. I can remember his imploring tone as he said ‘Will you chaps take me seriously? No one else will. For days our radar sets down on the coast have been jammed, and the jamming is getting worse every day. I am sure that the Germans are up to something!’ … he had reported the increase in jamming to the proper radar organization, but it seems that the increase from day to day was so gradual that most operators failed to realize how intense it had now become.1
To further illustrate the stratagem, Jones relates an incident perpetrated by R. W. Wood, an American physicist:
Wood at one stage in his early career worked in Paris and lived in a block of flats. He observed that the lady in the flat below kept a small tortoise in a window box. He secured a supply of tortoises of various sizes and by means of a grappling device … fished out the original tortoise and replaced it by one that was slightly larger. Over the course of a week or so, by successive small increases of size of tortoise, the lady was convinced that her pet was growing at an astonishing rate…. Wood … suggested that the lady might write to a newspaper about it. This she did…. Wood reversed his nightly procedure, and to everyone’s astonishment the tortoise gradually shrank to its original size.2
This is similar to techniques of expectation and assumption employed by magicians. Macknik and Martinez-Conde discuss these techniques in chapter eight of their fascinating volume Sleights of Mind. They note, for example, that “Once you’ve habituated to a feature of the world, it becomes a humdrum and seemingly immutable part of the fabric of life. Stable, reliable, unchanging.”3 Magicians, of course, generate and then exploit the seemingly humdrum in order to surprise and entertain. The Germans used the technique to surprise, although the British were most certainly not entertained.
A good red teamer does not stop there, however. Macknik and Martinez-Conde also counsel us to “Recall that one way to create strong misdirection is to give clues that a certain method is being used to accomplish a trick when in fact it’s a different method altogether.”4 Imagine in the case of the Channel Dash that the Germans gradually increased the level of jamming along the coast, expecting the British to detect it. The Germans could then apply a second layer of stratagem and use the detected jamming as a source of misdirection, perhaps with the intent of executing an operation elsewhere.