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

TOC Ch1 Ch2 Ch3 Ch4 Ch5 Ch6

CHAPTER 6

#### GEOGRAPHIC AND CLIMATIC FACTORS AFFECTING CAMOUFLAGE

| PARAGRAPHS | PAGE
Section I. Temperate Zone | 49-50 | 73
II. Desert III. Jungle IV. Snow | 51-55 56 57-62 | 73 78 80

SECTION 1. TEMPERATE ZONE

49. GENERAL. -- When not otherwise specified, temperate-zone terrain and climatic conditions are assumed in this manual.

50. SEASONAL CHANGES. -- Transition from one season to another brings marked changes in terrain coloring, requiring changes in garnished camouflage. More camouflage is needed when leaves are shed. Where rainfall is heavy, supports of flat-tops may require footings to counteract softening of the ground. When ground is frozen, counterbalances may be adopted to save digging holes for flat-top supports. Snow adds to the problem of camouflage maintenance because excessive loads on flat-tops may break them down.

SECTION 11. DESERT 51. CONCEALMENT FACTORS. -- a. Lack of natural concealment in the desert; lack of rainfall, causing dust clouds; high visibility and the bright tone of the desert-all necessitate special emphasis on siting, dispersion, camouflage discipline, deception, and the use of artificial camouflage materials. Desert areas are not always flat single-toned areas. They are frequently characterized by strong shadows and heavily broken terrain lines (fig. 82). Cast shadows in the desert are extremely conspicuous. When possible, installations and equipment are dug in. 73.

FIGURE 82. (90K) -- Desert area, showing characteristic variety of tones and shadows.

FIGURE 83. (99K) -- Six vehicles are concealed in this desert area. Ground views of four of them are shown in figs. 85, 86, 87, and 88.

FIGURE 84. (44K) -- Decoy train used in large-scale operational deception.

b. Many objects which cannot be made invisible from the air can be effectively concealed from ground views. Even though they are observed from the air, because of lack of reference points in typical desert terrain, they are difficult to locate on a map to aid attacking ground forces. For instance, an antitank ditch covered with wire mesh in which bunches of grass are fastened to match surrounding growth is visible from the air because of its deep shadow; but attacking tanks, with their limited visibility, often cannot distinguish the ditch from its surroundings This is true also of well-camouflaged trenches; covered and irregularly sited they lose much of their aerial visibility.

52. SITING. -- Siting is most important in the desert (fig. 83). Valley floors in most deserts have little natural concealment. Slopes into valley floors are often cut with dry washes. These terrain features support small plants, bushes, and trees and offer defilade and natural concealment suitable for vehicles and artillery.

53. DISPERSION. -- Vehicles maintain dispersed distances of 100 to 300 yards in bivouac or in movement.

54. ARTIFICIAL MATERIALS. -- Of all artificial materials, drapes garnished correctly as to colors and coverage are most commonly used in desert terrain. They must be tied in with natural terrain features, must be heavily garnished, and should be used over dug-in installations, if possible. It is especially important in the desert that sloping screens be used. This, however, does not mean that sloping screens are desirable elsewhere. Paint may be employed to tone down vehicles, tanks, and tentage. Colors in the desert generally must be very light, and simulated shadows very black.

FIGURE 85. (56K) -- Half-track, using desert scrub growth for concealment.

55. CONCEALMENT PRACTICE. -- In addition to using what natural concealment is present, digging in is important for all units. The following concealment practices are commonly used:

a. Foxholes are sited in the shadows of brush, gullies, and other natural objects, when possible; the openings are covered with artificial or natural material or with shelter halves. Spoil is widely and irregularly distributed under brush and in gullies. The visibility of wire is reduced by siting it irregularly, omitting long pickets, substituting bends for sharp angles, and following existing tracks.

b. Weapons emplacements are dug in; natural concealment is supplemented with drapes, flat-tops, and decoy structures. Artillery obtains defilade and concealment from ground observation, when mission permits, by siting in dry washes and other terrain depressions or among rocks.

c. Vehicles are dug in when possible. Use drapes, and site to take advantage of shadows and natural concealment. Trucks remove tarpaulins, if practicable, to reduce the size of cast shadows. These tarpaulins may be used as sloping sides on parked trucks to break the shadow. Vehicles may be painted with colors and patterns and allowed to stay dusty to blend with the surroundings. Tracks are brushed out, if possible, or continued past a dispersed position.

d. At depots, material is placed under underbrush or natural terrain features, draped, irregularly dispersed, toned down, dug in, covered with tarpaulins and sand, or covered to simulate existing terrain features, such as rocks.

e. Bivouacs are dispersed and sited in shadows of gullies, camouflage discipline is strict. Tents are painted with canvas preservative to match the terrain.

FIGURE 86. (178K) -- Tank parked in shadow of tree and draped with garnished twine net. 87. -- Light tank, draped with shrimp net, tied into nearby vegetation. 88. -- Light tank, draped with garnished twine net, hugs shadow of desert scrub growth.

SECTION 111. JUNGLE

56. a. Due to the abundance of natural cover in jungles, the type of enemy observation most frequently encountered is from the ground at comparatively close ranges. For this reason, and because jungle warfare is conducted largely by infantry in extended formations, camouflage is an especial concern of individuals and small weapons. Wide use is made of natural concealment by hiding, by blending with backgrounds and with shadow patterns, and by screening individuals and emplacements with materials found in the vicinity (fig. 89). There are many opportunities for small-scale deceptive practices. Overhead cover must be preserved, particularly near bivouacs and camps. Slashings in jungle cover draw immediate attention of enemy aircraft.

b. Certain individual items should be especially stressed. The proximity of the enemy and the concealment available to him make sound, light, and camouflage discipline especially important. Booby traps must be set carefully to warn of enemy approach. Special care is necessary in movement forward not to spring his traps or otherwise give him warning by disturbing local wildlife. In no operation is systematic scanning of the terrain ahead for selection of position and route of approach better rewarded. Silhouette against the skyline is a major problem. Cooking with its inevitable accompaniment of shine, smoke, and movement is a constant danger to mass movement. Insect pests and fatigue diminish alertness, and bare skin, in addition to being a health hazard, also shines. Likewise belt buckles, luminous watches, and other shiny objects are special hazards. Dark clothing is essential. Footprint tracking is common.

c. Concealment of mules is practically impossible where overhead cover is not available. In such circumstances, dispersion and great effort are necessary as the animals trample terrain and eat foliage.

d. In semi-open or open terrain, track planning is essential prior to vehicle movement. Use of natural cover, supplemented when necessary by drapes, is essential. Use knot and bow-tie garnishing, which matches foliage. Props must be used to break vehicle form. Selection of site is as essential in parking trucks as in other combat action. Dust clouds from vehicles draw enemy dive bombers.

e. Workshop sites, even when well sited, are revealed by concentrations of deadlined vehicles. This can be solved by (1) reducing the deadline by better maintenance and (2) restricting the number of vehicles permitted in the workshop area. A dispersal area within 5 miles can accommodate surplus vehicles.

FIGURE 89. (67K) -- Entrance to firing position concealed in jungle. Natural materials arranged over entrance and loop-holes would make position difficult to see at close range.

f. Headquarters, supply points, staging camps, and other concen- trations should not be in the vicinity of:

(1) The main track or line of communications

(2) Dropping ground.

(3) Track junction.

(4) River.

(5) Clearing.

(6) Gun position.

(7) Top of important feature.

(8) Captured enemy hutments or headquarters

(9) Accommodation or vacated headquarters which has been bombed already.

(10) Any obvious target.

Other things being equal, the best site is on the side of a hill, up a narrow re-entrant. In forward areas, if time permits, sleeping, office, and store accommodation should be dug in on a hillside if possible. On flat ground, accommodation is dug down. It is advantageous to have protective overhead cover, but if this is not possible, the roof and surfaces such as tent flies, waterproof paper, and similar materials should be covered with natural blending camouflage and maintained.

g. Sniping, mortar fire, and bombs are particular hazards. In defensive positions, trenches should have overhead protective cover at ground level and should be covered completely with natural camouflage. Communication or crawl trenches -also camouflaged- should be dug to alternate positions. Slit trenches should be covered with camouflage and have overhead cover if possible. Decoy trenches should be left open.

80 SECTION IV. SNOW

57. GENERAL. -- From the air, snow-covered ground is an irregular pattern of white, spotted with Hark tones (fig. 90). The dark tones are produced by objects protruding; above the snow and by shadows cast by irregularities in the snow surface, such as valleys, hummocks, ruts, and tracks. Shadows are comparatively gray in snow- covered terrain. Making sure dark military objects have dark terrain objects for background, avoiding movements that leave conspicuous and meaningful tracks, and maintaining military installations which are covered with snow so that the snow does not melt off and leave them conspicuous, are important. Camouflage discipline is highly important in snow terrain.

58. BLENDING WITH BACKGROUND. -- Imitating snow is difficult because it has great reflectivity. Care must be exercised in matching it, as its color varies from white to gray tones. White issue clothes used as outer garments for individuals, and white paint or whitewash for guns, tanks, and trucks are effective against direct observation (fig. 91). However, due to texture difference these techniques are not effective against aerial photography. At present no practical material has been developed to reproduce the texture of snow. In the field, paints should be used which are not affected by freezing temperatures, such as oleoresinous mixed with gasoline.

59. CONCEALMENT PRACTICES. -- Nets covered with large irregular areas of white cloth must be strong enough and well sup- ported to withstand heavy snow and high winds. Trucks, tanks, and supplies can often be concealed by throwing snow over them. Tracks show up even more clearly than they do on grass or ordinary ground because they cast shadows which show as dark streaks. Obliteration is almost impossible; hence, tracks should not stop at a place where they betray the presence of an installation.

60. DECEPTION. -- Deception has an important place in snow camouflage. Since paths in the snow are almost impossible to obliterate, one practice is to make many tracks that do not lead to an installation; the result serves to confuse the enemy. Shallow trenches in the snow, filled with grass, leaves, or brush look like deep defensive works from the air. Regular patterns of dark brush may easily be mistaken for batteries. Brush piles with paths radiating from them resemble command posts or supply or ammunition dumps. One of the best ways of making a decoy installation is to examine an aerial photograph of a camouflaged real installation and then to duplicate the track plan and some of the concealed objects by decoys. The decoy should be more conspicuous than the real installation, as though it had been badly camouflaged.

61. BARREN ARCTIC REGIONS. -- In barren arctic regions such as the Aleutian Islands, camouflage methods used in the desert can often be applied effectively. Strong winds usually prevailing in barren arctic regions make it necessary to use heavy strong construction.

62. NOTES ON SNOW CAMOUFLAGE. -- a. As the temperature falls, sound carries better in snow country, and great care must be taken to muffle the sounds of moving men and equipment.

b. In arctic regions the length of the night assists concealed movement. Camouflage discipline, well regulated, plus night movements can conceal the operations of a military unit successfully.

c. In arctic regions the attendant cloudiness of the sky often prevents or hampers enemy ground and aerial observation. Concealed movements can be made under such conditions.

FIGURE 90. (137K) -- Snow-covered terrain, viewed from tile air, reveals a surprising proportion of dark area.

FIGURE 91. (26K) -Gun is whitewashed and crew wears white clothing to blend installation into snow terrain.

d. The use of decoys as well as decoy tracks is particularly effective in snow terrain.

e. In soft snow care should be taken to brush out distinctive tracks, such as those made by tanks. When tanks turn quickly, small mounds of snow are piled up and reveal the nature of the vehicle. Such mounds of snow should be brushed out. If tanks turn slowly in a gradual arc, these snow mounds are not formed.

f. When it is desired to obliterate tank tracks on a hard crust of a road, use a road grader. g. Especial care must be taken to avoid shine from vehicles and equipment. Shine is often the only betraying sign of an otherwise well-concealed object in snow.

h. When bushes, buildings, and marked terrain lines are in evi- dence, parking procedure for vehicles is essentially the same as in temperate zones.

i. Leafy woods, orchards, and brushwood lose much of their con- cealment value in winter and should be supplemented by covers of white disrupted with branches.

j. When no white covers are available, dark ones can be used and covered with a layer of snow.

k. Thawing conditions are advantageous to camouflage since they reveal dark patches of ground which form a disruptive pattern. Vehicles and equipment can be made to blend easily against such a background.

l. In bivouac or in ambush, in deep snow, ditches may be made to conceal equipment or vehicles, but additional covers must be used to hide entrances. Track discipline must be rigidly maintained to prevent disclosure of the hiding place.

m. The degree of whiteness of artificial material employed must be carefully chosen. A hint of yellow or other alien color betrays the camouflage.

NOTES

[END]

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