The temptation in describing the 23rd’s visual deception work is to focus on the inflatable tanks themselves, as though the rubber Sherman were the essential element. It was not. An inflatable tank standing alone in a field would fool almost no one. What made the deception work was the complete environmental picture that the 603rd constructed around and beyond the individual props.
Track marks in the mud suggested movement of vehicles that had arrived from outside the visible area. Camouflage netting deployed over particular positions suggested the presence of concealed equipment valuable enough to hide. The placement of communications equipment at positions consistent with an infantry division command post suggested that a headquarters was operating there. The distribution of positions across terrain — tank assembly areas in locations appropriate for armored concentration, artillery positions on appropriate ground — suggested a unit disposed according to doctrine.
The German intelligence analyst looking at aerial photographs of this area would not have seen rubber tanks; he would have seen visual evidence of the full range of operational activity that two infantry divisions would generate. The rubber tanks contributed to this picture, but so did the terrain modification, the netting, the equipment placement, and the deliberate management of vehicle traces.
This holistic approach to the visual environment was itself a form of knowledge — an understanding of how military formations appeared from above and what specific signatures each type of activity generated. The 603rd had to understand German photo interpretation well enough to construct a scene that would satisfy it. Creating the deception required being able to adopt the analytical perspective of the opponent.