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WAR DEPARTMENT FIELD MANUAL (1944)
FM 5-20
CAMOUFLAGE, BASIC PRINCIPLES

TOC Ch1 Ch2 Ch3 Ch4 Ch5 Ch6

CHAPTER 5

DECEIVING

43. DEFINITIONS. -- a. A decoy is a false military installation designed to simulate a real activity and thus to attract enemy attention (fig. 78). It may consist only of signs of activity, such as simulated blast marks or wheel tracks.

b. Decoys are camouflage weapons of deception. Since large-scale deception planning may give an effect of strength or weakness, plans for such work must be approved by higher commanders (see par. 3c) .

44. EMPLOYMENT. -- a. The use of decoys in combat zones depends on many factors. Decoys must be located in logical positions far enough away from actual targets to prevent enemy fire on the decoy from hitting the real installations. This distance depends on the size of installations and the type of enemy observation and fire

FIGURE 78. (94K) -- Decoy batteries of field artillery using abandoned positions.

FIGURE 79. (58K) -- Decoy truck made of frame covered with cloth.

expected. Decoy bridges, dumps, railheads, and airfields may be 2 to 5 miles from the real object, while decoy field artillery or antiaircraft-artillery batteries may be less than 1 mile away. In all cases, the location of real installations must be carefully considered when siting decoys so that the decoys do not draw fire on the real installations.

b. To deceive the enemy, a decoy simulating a large rear-area installation generally should be sited to have approximately the same relationship to near-by landmarks as the target itself. Landmarks are likely to be used as enemy reference points.

45. THEORY OF DECOY DECEPTION. -- a. A decoy installation must avoid the appearance of being a decoy. It is so constructed that its disclosure to the enemy appears to be the result of defects in its camouflage. There are various methods for accomplishing this deception, such as the disclosure of parts of a decoy, leaving tracks, incomplete concealment of shadows of decoys, or the improper use of surface texture or color. If a decoy draws attention away from a real installation, it serves its purpose. A decoy position which has been discovered to be such by the enemy may later be occupied as an actual position.

b. To be effective, the decoy installation must include features normally associated with the real installation and must be properly maintained. For instance, decoy planes on an airfield must be moved from time to time; in the case of decoy trucks, a few real trucks should be used to make tracks; in every case the effects of normal activity should appear.

c. Decoys intended to divert attention from real objects or instal

FIGURE 80. (50K) -- Three-dimensional appearance of building simulated by paint alone.

lations are effective only when the real objects are completely concealed. A decoy must bear a convincing resemblance to the true object or activity it simulates. If it is suspected as false, it will attract enemy attention to the area.

46. MATERIALS AND FORM. -- a. While imitation of the form of the genuine object is sought in the construction of decoys, they are built along the simplest possible lines. In combat areas, field expedients are important. Construction may consist of earth and brush, rough timber or framing covered with cloth (fig. 79), building paper, screening, or wire netting garnished with chicken feathers or cloth. All the standard camouflage materials may be used for this purpose.

b. It is possible to simulate the minor elements of a large installation by means of paint alone. Thus, the principal decoy buildings of a decoy installation can be built in three dimensions, and other structures painted on the ground (fig. 80) . However, lack of shadow, or the unchanging direction of painted shadows, is likely to give away such decoys when aerial photographs are closely studied.

47. USE OF DECOY TRACKS. -- On occupying an area, a large unit can often deceive the enemy by constructing numerous turn-outs from roads and railroads into woods not occupied for military purposes (fig. 81 ) . This is likely to draw enemy artillery fire or bombing missions. Later, after enemy action has ceased, if it becomes necessary to occupy the wooded area, the decoy turn-outs can be used for entrance without changing the appearance on aerial photographs.

FIGURE 81. (102K) -- Deliberately made paths and tracks give false indication of military occupation.

48. CHECK LIST. -- To insure realism in decoys and to guard against common errors in construction and operations, the following points should be checked:

a. Are a few indications of the presence of allied or supporting objects included? For example, decoy artillery positions may have signs of prime movers and communications.

b. Is location logical for a real installation? Is position continually maintained? For example, a decoy railhead which has been bombed should have bomb damage repaired.

d. Is the scale of the decoy object or installation approximately the same as that of the real object?

e. Do simulated roads and paths appear worn ? Turns should not be too angular, and edges should be uneven.

f. Are shadows lacking? If present, are they in the correct place relative to the actual object?

g. Are signs of attempts at camouflage included?