In the defense of rear areas, the Germans lay much stress on the use of passive means. These involve every feasible type of deception, including the extensive use of camouflage. No effort has been spared to change the appearance of important potential air objectives as completely as possible. In 3 years of war, the system has been developed to a very high degree of efficiency. AA artillery units cooperate in the system of passive defense by the use of movable defense forces, and through carefully considered gun and searchlight positions. The civil population is well disciplined, and blackout regulations are stringently enforced.

Obviously, it is impossible to conceal the general location of a large military objective such as an industrial city. The Germans recognize this fact, and their attempts to deceive their enemy accordingly include removal of the center of gravity of the defense of the area from the center of the objective area itself. At night this is accomplished largely through the use of searchlights. A hostile flyer will usually fly toward the center of the ring of illumination, since he will assume that the center of the objective should be in that area. Under the German system, the center of the ring of searchlights is accordingly placed to one side of the center of the defended area. Furthermore, the center of the searchlight defense may be moved from time to time, thus precluding any definite "fix" of the center of the searchlight defense with respect to the true objective. For daytime deception, camouflage will be used to a very large extent, no effort being spared to bring about the maximum results.

In line with the German belief that if a considerable portion of the enemy attack can be diverted to dummy objectives, the defense may be considered to have been quite successful, the Germans use complete systems of dummy objectives around their important military establishments. Some of these dummy objectives have been so successful that they have been bombed by hostile aviation many times over. Active means are used to assist the effectiveness of the faked objectives. For example, at night when hostile aircraft bomb the dummy objectives, personnel housed in nearby bomb-proof shelters will start large fires to cause further bombing attempts at the objectives, and to confuse the fliers as to the outcome of their mission. To increase the effect of reality, in many cases the dummy objectives may be protected by AA artillery. Captured materiel is often used for this purpose. Dummy objectives are also placed near the center of the searchlight perimeter. The use of dummy gun positions has already been mentioned. When these positions exist, the mobile section of the active AA artillery defense may move in and out of them. The use of dummy flashes may intermingle with the firing of real AA guns, as a result of which the hostile flier secures a very incorrect picture of the true situation on the ground.

Some examples of the extent of the use of camouflage by the Germans will not be amiss. It is well known that Berlin has been extensively camouflaged, not only the city itself but also the outskirts. One example is that of the most important distinguishing landmark in Berlin, namely, the wide avenue running east and west through the city and called the "Axis." The pavement of this avenue has been sprayed with a dark green paint to blend with the trees in the Tiergarten (a large park), along the avenue and throughout the western section of the city. The Victory Monument (Siegesäule), in the center of a circle on the Axis, has been painted with a dull color so as not to reflect light. An overhead cover of wire matting, interwoven with green materials to resemble vegetation, covers the avenue for a considerable distance. The wire netting is about 18 feet high and is interspersed with artificial shrubs and trees. About every 30 yards, the coloring and texture of the greenery has been changed. To eliminate shadows, netting has also been hung from the sides at an angle of about 20 degrees.

To create an opposite effect—that is, to simulate a street where in fact there is none—wire netting has also been used. These dummy streets are frequently connected with the real ones, which then disappear into artificial woods. In one instance it is reported that a "woods" was created by fastening artificial sprigs about 1 foot high and about 1 to 2 inches apart to a wire net. Through these "woods" a system of "roads" was painted in brown on the mesh of the net.

Many important buildings in Berlin have been camouflaged by covering them with nets, and by placing artificial barns, farm buildings, and trees on the roofs. Small lakes have been covered by reed-like mats.

The extent of these camouflage efforts is a good indication of the lengths to which the Germans will go in carrying out large-scale efforts at deception. It may well be expected that no means will be spared to hide the real disposition of gun positions and vital areas.