Bible Encyclopedias
Camouflage

1. Colour

The sandy-coloured desert animal and the green caterpillar are examples of the use of colour to produce general inconspicuousness. Browns, greens and greys, being common background colours, are usually used. Bright colours such as yellows and reds are occasionally made use of, for instance, by insects amongst autumnal foliage. Even before military camouflage had been systematically studied, most armies had adopted inconspicuous field service uniforms.

2. Tone. - This is a quality of great importance in camouflage, for the reason that aerial photography was largely used for its detection. In the concealment of animals it is also of considerable importance, though somewhat lost sight of in local colour. An animal which is either darker or lighter than its surroundings will be likely to be revealed in spite of being well coloured. In artificial camouflage it was found that the right tone could be more easily effected by texture than by, for instance, pigment. Thus, the imitation of grass could not be made with green paint on a smooth surface: from one point of view it might simulate well, but from another angle it would reflect a high light (see section II below). Roofs of buildings were concealed by covering them with hay, heather and brushwood stuck to the roof with an adhesive paint.. The appearance of rough ground so produced could not have been obtained by any kind of painting. But although texture is of so much importance, it must not be thought that local colour can be entirely ignored. The aeroplane photographer used plates sensitive to particular coloured lights or colour filters which had the same effect, namely the detection of any fault in local colouration. The Germans used a green sensitive plate which, no doubt, would have detected a brown camouflage erected on a green field, even if the tone-match had been good. Moreover, the aeroplane carries a human observer as well as the camera.

3. Outline

The production of inconspicuousness by pattern is utilized by animals moving from background to background, which are now seen against foliage and now against brown earth. An animal broadly patterned in green and brown will appear inconspicuous against both these backgrounds and is recognized principally by its characteristic outline or silhouette. Against earth, only the green of the parti-coloured animal will be seen, and this will not have the characteristic shape of the animal, neither will the brown part of the pattern when it is viewed against foliage. The most efficient pattern is one which greatly disrupts the characteristic shape; one, for instance, which breaks out at conspicuous angles or across easily recognized straight lines and curves. Thus, birds commonly exhibit a pattern which divides the head into two, along the line joining the base of the bill with the shape of the neck, and the characteristic straightness of the tail is broken by cross-bars of pattern. A thin, dark or light, line separating the components of the pattern greatly aids its disruptive effect. This method of concealment has been used for guns and other objects, on which patterns of dark green and brown, separated by narrow black lines, were painted in large irregular blotches across the barrel, wheels and limber (see section II below).

There are other ways by means of which outline mayi be concealed. Among birds and insects fringes are sometimes made use of: viewed at a distance, the fringed edge has a blurred appearance causing the object to fade into its background. This principle of the fringed edge was freely and successfully employed in military camouflage, notably in the case of the flat-topped gun covers described in section II. Among insects an edge is often made to appear indistinct by a small marginal pattern of dark and light tone. When viewed at such a distance that the pattern is blended, the edge appears blurred. This is in principle quite different to disruptive patterns, which are only effective as long as they are visible, whereas the marginal patterns are only effective beyond their blending distance.

4. Modelling and Cast Shadow. - Modelling is revealed to the eye by the varying amount of light reflected from different parts of the object, and also by the shadow cast upon neighbouring objects. Animals and birds are often toned so as to appear flat by having those parts which are turned towards the light dark in tone; and those away from the light, light in tone. It is common to find the backs of birds dark-brown or black and their breasts white. When viewed in the open, the high light which is reflected from the back is subdued by the dark feathers; whilst the darkness of the under parts is partially neutralized by the white breast feathers. The whole bird will thus appear evenly toned like a flat object and for this reason will be inconspicuous.

This method, called counter-shading, was occasionally made use of in military camouflage.

As regards the concealment of cast shadow, the only method employed by animals is to avoid them. Insects will turn and face the sun so that their closed wings will only throw a line shadow on the ground: others will tilt their wings parallel with the ground, thereby hiding the shadow which they cast. In military camouflage on the other hand the difficulty had to be faced, and an ingenious and successful method was evolved in the case of the flat-top gun cover. The cover consisted of wire or fish netting, on which strips of canvas were threaded and knotted. These strips were coloured green or brown in imitation of grass or earth. By gradually thinning out the knots at the edge, the shadow of the thickly knotted centre was hidden by the sparsely knotted margins which themselves cast little or no shadow.

The above outline will suffice to give a general idea of the relation between animal colouration and camouflage. But it should be added that the camoufleur has much greater difficulties to contend with than has the animal on account of the extremely accurate and systematic observations made by the enemy with the eye from forward observation posts and kite balloons, and with the camera from aeroplanes. U. C. Mo.) II. Military Camouflage The word " Camouflage, " in the broad sense of military deception, is applicable to all stratagems designed to mislead the enemy. In the following account it is used in the restricted sense of " deception practised through the agency of artists." The application to war of camouflage, as thus defined, is by no means novel; dummy guns have been successfully employed to mislead an opponent on occasion ever since guns became a normal part of military equipment. Washington Irving in his Conquest of Granada records an instance in which the ruined wall of a blockaded town was repaired, without attracting the enemy's attention, under cover of a cloth screen painted to resemble a battlemented wall (circa 1484). The Venetians are reputed on one occasion to have imposed terms of peace on Ragusa by the expedient of building a threatening fort of cardboard in a position commanding the town. And when Henry VIII. of England besieged Tournai in 1513, the defenders used lengths of canvas, painted to resemble trenchwork, to mislead the besiegers as to the extent of the defences. Other instances could no doubt be brought forward in which camouflage was practised by individuals as an expedient. But it was not till the World War that it was practised by armies as a policy.

A transitional stage between the spasmodic use of camouflage in emergencies and its regular and systematic use as in the present day is marked by the painting, or other treatment, of coast defence forts 'to blend with their surroundings, in order to render them less conspicuous from the sea, e.g. Cork harbour, Isle of Wight, Singapore.

The well-known chequered black-and-white of the Spithead forts was an attempt to mislead the enemy as to the exact location of the gun embrasures. The same artifice was used in the case of the loopholes of blockhouses in the South African War of 1899-1902.

A further stage was reached in the adoption of uniforms coloured to blend with the usual or typical colours of the countryside in a theatre of war. The first of these was the Indian Kliaki (see 15.770), and after the experience gained in the South African War, when the importance of concealment came into great prominence, the British and most other armies soon adopted dust-coloured, light-blue, grey, or grey-green uniforms.

Shortly after the South African War, experiments in the disruptive painting of guns were undertaken, but the system was not adopted, and no further development in the practice of camouflage took place until the war of movement of 1914 gave place to trench warfare. Hitherto deception in war had been limited to the comparatively simple task of deceiving the human eye, at a considerable distance, and for a short time. In the World War its role was extended to circumventing the camera, in addition to deceiving for long periods, the eyes of observers armed with powerful glasses. For the first time in history, a military unit was organized for the definite purpose of practising scientific deception.

This policy was initiated by certain French artists serving in a French battery towards the end of 1914. The interest of a French army commander was aroused and his sympathy enlisted, with the result that a " Section de Camouflage " was formed early in 1915, for the purpose of assisting units in the concealment of battery positions and other military works, and the construction of concealed posts of observation. The success attained by this section led to the organization of the British Camouflage Service as a unit of Royal Engineers, early in 1916.

The need for organized camouflage is directly attributable to two novel features of the war, firstly the prolonged period of stationary warfare; and secondly, as an outcome of the first, the rapid development of aviation generally and of photography from the air in particular. Stationary warfare entailed the prolonged occupation of definite localities by troops, guns, and other numerous appurtenances of war, whose installation tended to become semi-permanent instead of temporary. It was therefore possible for each opponent methodically to examine the other's battle area in detail, and at comparative leisure, instead of relying on promiscuous and hurried reconnaissance, as in the past. It was soon recognized that photography provided the best means of executing such detailed examination, and presently the art of interpreting air photographs almost reached the level of an exact science. The information thus obtained far exceeded in quantity and accuracy that gleaned by observers, who could not but be distracted by the expanse of the view beneath them and the incidents of their adventurous journeys. All the resources of science were therefore devoted to the production of lenses, plates and colour screens, specially adapted to the needs of military intelligence. This evolution in the means of obtaining information necessarily called for a similar evolution in the means and methods of denying it, and a special service was organized for the study and practice of the science of camouflage.

The taking, developing and study of photographs demands a certain amount of time and special appliances, and still more so does the study, production, and application of camouflage, of which the progressive stages are performed on foot, in a large well-equipped factory, and in slow-moving lorries and trains. As long, therefore, as a condition of stationary warfare obtains, the maintenance of a special organization to practise camouflage is both necessary and possible.

But the conditions of a war of movement are quite different. Installations and constructions of all kinds are few. The occupation of localities by troops and guns is fleeting, and, in consequence, the camera loses its specialized usefulness. It follows, therefore, that the elaborate concealment of gun positions or other works is no longer necessary. Nor is it possible, for the transport, on which the camouflage service relies, is engaged to its utmost capacity in conveying the vital necessities of war, i.e. food and ammunition; and at the same time the factories, on which the supply of the material of camouflage depends, are being left farther and farther in the rear - or being engulfed by the advancing enemy, as the case may be.

The case may be summed up thus: - when accurate means of locating positions are employed, expert methods of concealment become essential; when the converse obtains, extempore methods suffice, though some form of portable camouflage, designed for use in moving warfare, and carried as part of their normal equipment by fighting troops, would be preferable.

There is ample evidence to prove that the Central Powers took no steps to organize a camouflage service till late in the war, though extempore methods of concealment were universal. Captured documents bear few allusions to the subject until after the battle of Cambrai in Nov. 1917. In the great offensive of March 1918, the Germans captured many specimens of camouflage together with pamphlets on the subject which they translated and distributed to all formations; at the same time arrangements were made for the quantity production of materials for concealing gun positions. In the Entente offensive of autumn 1918 man y specimens of this material were captured for the first time, together with numerous examples of instructions on the practice of camouflage.

The principles and practice of camouflage may be dealt with under three heads: (I) the concealment of gun positions and the like from the enemy's aeroplanes (" air observation "); (2) the concealment of observation posts and machine-gun emplacements from direct view (" direct observation "); and (3) miscellaneous applications of camouflage.

(1) Camouflage against " Air Observation." The purpose of camouflage is to render objects indistinguishable, or un recognisable, by means of imitation or disguise. Concealment in the limited sense of " hiding from view " is not the primary aim. The ideal is non-interference with the natural, or normal, aspect of the locality, as viewed from the air, with which the enemy has become familiar. This is an ideal which can only be reached by close attention to detail, and by the exercise of forethought and imagination.. Preliminary study of an aeroplane photograph of the locality will enable the effects of preparatory work, and subsequent active occupation, to be foreseen, and consequently make it easier to plan methods of combating them. These methods must be put into force before commencing work. To do so afterwards is futile, unless it is certain that no observation from the air has been possible during the progress of work. The processes of successful camouflage are closely analogous to those of successful crime - namely, preliminary reconnaissance, suppression of clues, provision of false clues, variety of method and concealment of the crime itself.

In-the following study of the principles of camouflage the subject is dealt with in relation to the concealment of gun positions. In practice many other works were also concealed, such as machine-gun emplacements, defences, dumps, mine spoil, gas projector installations; but similar problems are encountered in all these cases.

Gun positions can be located by (a) aeroplane photography, (b) air observation, (c) flash spotting, (d) sound ranging. The two last furnish certain limited information. Beyond screening flashes, no method of frustrating them has yet been evolved. The manifest remedy (failing a silent, flashless propellant) is the skilful employment of dummy flashes and synchronized reports. But it is principally by means of photographs taken from the air that positions are definitely located on a map. The chief opponent to be overcome, therefore, is the expert, who, with the advantages of time and undisturbed concentration, which are lacking to the aeroplane observer, is able to interpret what is recorded on photographs. The aeroplane observer cannot, however, be altogether disregarded, and, although the main efforts must be directed towards defeating the air photograph expert, it must be done in such a way as not to draw the attention of the observer.

The camera is a most accurate witness, and a photograph will always record something. The art of camouflage lies in conveying a misleading impression as to what that something signifies. The photograph records colours and accidents of ground (such as bare earth, vegetation, woods, etc.) in terms of light and shade, and is a patchwork or pattern of black and white meeting in varying intensities of grey. The pattern may be large and simple like that on a chess-board, or intricate and confused like that on a painter's palette. A cultivated district presents a regular chess-board pattern, with large rectangular expanses of monotone, the only accidents to break the monotony being occasional hedges, banks, or houses, with their attendant shadows. Broken ground, such as demolished villages, shelled areas, or patchy vegetation, presents a highly complex pattern, full of merging lights and shades.

Photographically, the effect of colour is not so marked or important as the effect of light and shade. Earth is towards the white end of the scale, and grass or vegetation towards the black - not because of their respective colours but account of the amount of contained shadow or " texture." A billiard-table or top-hat illustrates this quality. Brush them the wrong way, against the nap, and their tone is lowered to dark green in the one case, and dead black in the other; brushed the right way they appear very noticeably lighter in tone. The reason is that they gain " texture " when brushed the wrong way, and lose texture when brushed the right way. In other words, they absorb light in the former case, and reflect light in the latter. Nap is constituted of countless slender hairs, each one throwing a shadow when erect, but casting little when flat. Grass, or vegetation, possesses this same property to a marked degree. The longer it is the darker it appears on a photograph; but when it is pressed down, the amount of shadow thrown is lessened, and consequently it appears lighter. Hence the obvious ness, on a photograph, of a slightly worn track in grass which is scarcely noticeable when viewed from the ground. Earth, on the contrary, contains little texture, and the longer it has been turned up and exposed to rain and sun, the less it contains. A beaten track is, however, conspicuous as it contains no texture at all, and will therefore reflect more light.

The reason for the mottled effect, in a photograph, of a patchy mixture of grass and earth, which blend imperceptibly into each other, is therefore evident. The appearance of snow can be divined from the foregoing. Contrasts in tone are much accentuated, and the effects of shadows are more marked, partly owing to the fact that snow usually falls at a time of year when the sun's path in the sky is low.

It is essential, when judging the colours of a locality, to view it vertically, and not obliquely as one is accustomed to see a flower bed. A field of young corn, surveyed from the ground, appears green, but from above,. probably the earth only is seen, darker in tone than the normal, owing to the shadows cast by the young blades of corn. Similarly, with a field of ripe corn the actual light tone of the straw and ear will be somewhat darkened by their shadows.

It is of the first importance to grasp this principle of regarding any locality purely from the point of view of the pattern it will present on a photograph. Therefore, the most practical method of planning the concealment of any work is to plan it with reference to a recent photograph which records the ground pattern, and the natural facilities for concealment which exist in the locality. Such facilities abound in a neighbourhood whose photographic pattern is complex, and become less frequent as the pattern becomes less complex. Any slight error in exact reproduction may escape notice in the prevailing complexity, because detection depends on comparison, and comparison is rendered perplexing by the very intricacy of the pattern; the difficulty is enhanced by the variations present in successive photographs of the same place, due to dissimilar conditions of light. A simple analogy is the comparative visibility of an ink stain on a patchwork hearthrug and on a table-cloth.

There are certain characteristic clues which will always betray new work to the reader of aerial photographs. They are: (a) disturbance of soil; (b) tracks; (c) shadows; (d) regularity; (e) blast marks of guns. To achieve success, these clues must be suppressed from the very beginning. Or if deception is to be achieved by the use of dummies, these clues must be supplied.

The prolonged duration of the period of trench warfare was responsible for the introduction of many new methods of waging war scientifically. Among these was the systematic study of the enemy's normal activities, as gauged by observation over a long period, to determine such things as average intensity of gunfire, movements behind the lines, density of traffic, number of hospitals, size of dumps, etc. The chief evidence was obtained from photographs, taken at regular intervals, of the whole enemy front to a depth of several miles. Comparative analysis of this photographic diary revealed departures from the normal from which deductions could be made. It was therefore of the utmost importance to preserve an appearance of " normality." Clues (a), (b) and (e) call for no special comment, but some further explanation may be added in the case of shadows and regularity.

Shadows

The form of any erection, or excavation, is revealed in a photograph by the shape of the shadow cast. Two intersecting planes, e.g. the two sides of the roof of a building, will show differently on the photograph (except for a very brief period every day) because they receive light at different angles, and therefore reflect it differently. It follows that an artificial reproduction of locality must be erected parallel to the contours of that locality, or in other words the planes of the imitation and the real must not intersect.

A mound must be imitated by a mound, and a flat surface by a flat surface. Any departure from this principle is most easily detected in a photograph taken when the sun is low, the shadows being long in consequence.

Regularity

No shape in nature is of regular outline; consequently anything of a regular shape in a photograph invites scrutiny because it must be the work of human hands. In a battery position, regularity is usually displayed in the geometric shape of the gun-pit, and the regular spacing and alignment of the guns.

It is now possible to sum up the theoretical conditions which govern the concealment of gun positions, and other works, from the enemy in the air: (a) The material of which the camouflage is composed must at all times appear on the photograph like the object or surface it represents, and likewise appear natural to the observer's eye. Qua material, it must be light, strong, impervious to weather, fire-proof and easily manufactured. (b) Disturbances of soil, tracks, shadows, blast-marks and regularity must never appear to be associated with an active gun position or occupied work.

Practical Application

We come now to the application of these principles. In the early part of the World War air photography was not the highly specialized art it subsequently became, and therefore the difficulties of combating it were not so great. At first, freshly cut branches and grass were used, being the materials nearest to hand. These withered in the course of a few days and ceased to be efficacious. The next stage was the employment of sheets of canvas painted to represent the ground. The design was bold, and consisted of large masses of green, or brown and green as the case might be, with heavy black shadings, to give the effect of texture. These covers were draped over the guns and came down to the ground on every side, being removed when the gun was in action and replaced immediately afterwards. This system also proved unsatisfactory. It is nearly impossible to reproduce on a smooth sheet of canvas the changing tones of the ground as recorded by the camera. Under certain conditions - i.e. when the angle of light incidence is small, or after rain - painted canvas, having no texture, reflects so much light that all trace of pattern or colour is lost.

Then came the introduction of fish netting. At first these nets were garnished sparsely with bunches of painted raffia (gardeners' bast). The effect was excellent; the nets were light and portable; but the inflammability of the painted raffia was a grave disadvantage. Efforts made to dye the raffia and to render it fire-proof proved fruitless. The dyes, especially green, were too fugitive, and no method of rendering the raffia permanently fireproof could be discovered. Strips of painted canvas, instead of raffia, proved more satisfactory from the manufacturing point of view, but these also suffered from the defect of inflammability,' though in a lesser degree. The final evolution of the gun cover was a net having an opaque centre of painted scrim,' the shape of which was boldly irregular, with a border of painted canvas strips decreasing in density towards the edges, erected horizontally, like a carpet, over the work and much larger in area than the work itself (see fig. 3). Thus, the excavation was concealed by the opaque centre, the shadow of which was blurred or masked by the border of strips which, in themselves, were not sufficiently dense to cast a shadow. If skilfully erected and maintained such covers were satisfactory. Installed before any work of excavation was started, subsequent construction and occupation remained concealed. Guns could be treated individually or collectively by increasing the area covered. Figs. i and 2 show the treatment of a battery position placed under the edge of a bank. The false edge of the " bank " should be noted.

The use of netting was practically confined to works whose nature demanded covers erected at a considerable height above ground level. Scrim was used, by itself, to conceal objects near, or on, the ground, such as short lengths of trench, ammunition, gas-projectors; it should always be reinforced by natural material to increase its texture effect. Further, this material must always be cut or assembled in large fantastic shapes, in order to appear natural, and to allow its edges to merge gradually into its surroundings.

Many gun positions, which had defied all attempts at location, were betrayed by snow, particularly in respect of blast marks, because the flash of discharge melts the snow over a large area immediately in front of the gun. Further, shadows were accentuated, and the normal method of combating shadows, by the adoption of thinned edges, proved fatal in snow, as such nets 'A solution of this problem of fire-proofing canvas was in sight when the Armistice put an end to its urgency.

'A kind of loosely woven canvas whose meshes give the effect of texture by absorbing light.

did not hold the snow and consequently appeared as black holes in a sheet of white. White calico proved a palliative, especially in the case of blast marks, if boldly irregular in shape.

Evidence afforded by tracks is perhaps the most difficult of all to eliminate. Frequently positions, which are admirably concealed in every other way, are betrayed by the tracks leading up to them, so much so, that it is often possible to count the number of guns in a battery by the paths leading to each gun-pit and to distinguish between gun positions and other works. It is comparatively easy to plan the approach so that it may be concealed naturally or artificially; the difficulty is to ensure that this and no other route is used - human nature being so strongly addicted to taking short cuts, barbed wire and discipline seem to be the only means of preventing it.

The following afford good illustrations of methods of concealing approaches that have been adopted with success: (a) Leading the track close past the gun position and on to join an existing track. The connexion to each pit being treated with camouflage material or cut grass, etc.. etc. (b) Similarly, but close in front of the gunpits in order to use the track to hide blast marks. This method has the disadvantage of restricting traffic while the guns are in action. (c) Siting a battery in the midst of an existing network of tracks, taking precautions to reproduce on the camouflage any path interrupted by a gun-pit.

It is not practicable to conceal long trenches. If a covering sags or differs materially in tone from its surroundings the mere length and regularity will betray it. A covering, originally perfect, will require continual attention to keep it perfect, involving labour out of all proportion to its value. Short lengths of trench can be concealed, provided care is taken to support the camouflage adequately to prevent sag, and to conceal the spoil.

This applies equally to trench systems prepared far behind the lines for use in the event of a retirement. It is probable that the enemy, foreseeing the construction of such a defensive line, will be able to guess the approximate positions of such systems, and he is certain to have periodically photographed the suspected area. It is quite impossible to prevent some traces of work being evident in a long and deep system of defences. Camouflage must obviously be restricted to vital spots, and extreme care must be exercised (2) Camouflage against Direct Observation. - The concealment of observation posts was comparatively simple, being merely an adaptation of the craft of theatrical property-making. Natural features were selected, in places from which good observation could be obtained, and these were copied exactly. At night, the real was removed and replaced by the imitation. A large variety of objects were so copied among which may be mentioned: - trees, sand-bags, milestones, mounds of earth, chimneystacks, walls. In all cases the copy was a thin outer shell containing a bullet-proof lining in order to give confidence to the occupier. The loopholes, when subject to scrutiny at short range, could be made quite invisible by the use of gauze, which, though painted to resemble the exterior of the O.P., remained transparent from the inside. This method was only adopted when absolutely necessary, because gauze interferes with vision - especially through glasses; in other cases care was taken to give the loophole an irregular shape.

Certain conditions were found to govern the successful employ ment of these observation posts, particularly in the case of the more elaborate examples such as trees.

a. Concealed access is essential.

b. The work connected with installation must, like other work, be concealed from the air.

c. They should not be erected in places that are normally subject to heavy shelling, for the reason that careful observation will be prejudiced and accidental damage will probably reveal the observation post to the enemy.

d. Provision must always be made to prevent daylight showing behind the loophole, so rendering it transparent to the enemy.

e. The comfort and security of the observer must always be studied, otherwise the full value of the observation will never be obtained.

Imitation trees (see fig. 6) were designed either to accommo date an observer at a commanding height above the ground, or to conceal a long periscope, the user of which was protected in a strong dug-out. In the former case the observer had a better view, but was uncomfortably cramped. The periscope is limited in respect of magnification, field of view, and clearness of vision, in proportion to its length. On the other hand advantage may be taken of its length to obtain high command with comparative security, or increased security with low command. Further, with suitable mountings, it can be used as an instrument of precision in conjunction with map and compass. Provision should always be made to give bullet-proof protection to the periscope when in use, and to allow of its being lowered for cleaning and safety when not in use.

It was sometimes necessary to construct machine-gun emplacements for defence in positions that either were, or might be, exposed to direct view. In certain cases the emplacement was incorporated in some existing ruin, parapet, or such-like protection, where it was only necessary to conceal the embrasure. This was effected by the use of gauze painted to resemble the exterior, either in a hinged frame which could be removed for action, or fixed and fired through when need arose.

In other cases the emplacement was in the open. In such circumstances full precautions had to be taken to guard against detection by the camera also. An additional danger lay in the risk of detection from low-flying aeroplanes. To meet this a movable cover was evolved, in the nature of a lid, suitably disguised to resemble the surroundings (see figs. 4 and 5). Normally this lid reposed on the top of the emplacement, Overlapping it considerably; in action the lid could be raised vertically a foot or two, still affording protection against view from overhead, and also, to a partial extent, against long-distance direct view.

As a general rule, the screening of roads from observation by the enemy is not in the province of camouflage, in that no deception is attempted, the main object being to conceal traffic from direct view.

In a few instances true camouflage was practised when a screen painted to represent the enemy's accustomed view of the locality was erected between the road and the enemy, so that the road would always appear unused even while traffic was passing behind the screen. Such an expedient was restricted to a few favourable places, such as occasional gaps in a road otherwise entirely hidden from view, or open spaces in a village where the ruins for the most part obstructed the enemy's vision. These screens were impracticable in cases where the portions to be concealed exceeded a few yards in length, as they were exposed to the weather and casual shelling, and therefore had to be very strongly constructed. This, combined with the necessity of complete erection at night and the fact that they could be used only where the locality was not subject to marked seasonal changes, considerably limited their use.

(3) Miscellaneous Applications of Camouflage. - It was only natural that, after a camouflage unit had been organized, with skilled personnel and well-equipped workshops, there was a wide field for the display of ingenuity. For the most part the field has been covered in the foregoing sections dealing with the methods of combating air and ground observation, but it will be of interest to give a short description of devices that fall outside these two categories.

Dummy Attacks

In 1917 the practice of raiding the enemy trenches increased in frequency and scale, and in order to secure the best results with the least expenditure of life, dummy attacks were frequently staged on the flanks of the real front of attack, and set in motion a few moments before it. The dummy (or " chinese " as it was called) attack consisted of numbers of lifesized silhouette figures, made of stout millboard and painted to resemble the various postures of advancing troops. These figures were placed in scattered groups of ten, and suitable arrangements made to raise and lower them at will from some place of safety, so that they simulated waves of advancing troops (see fig. 7). In the early light of dawn, or partially obscured by smoke, they were very realistic, but success depends on skilful operation of the figures rather than on the painting. Directly the enemy's fire was drawn the real attack was launched with the comforting knowledge that many precious moments must elapse before the enemy could switch his fire off the dummy attack on to the real attack.

Similarly, the location of enemy snipers was facilitated by the use of dummy heads made of papier-mâché. These were exposed over the parapet, in a life-like manner, in order to draw the fire of an enemy sniper. If the head was hit, it was possible to locate the exact position of the sniper by producing the alignment of the holes of entry and exit of the bullet. It was necessary to paint these heads with a matt surface, darker in tone than the natural, in order to imitate the texture of the human face.

Sniper Suits

The concealment of snipers and scouts was facilitated by the wearing of costumes painted to match the surroundings. When garnished with local vegetation, and used skilfully, it was extremely difficult to discover the wearer. Fig. 8 shows an exceptionally tall man lying quite in the open, but wearing a sniper's robe. Fig. 9 shows, in contrast, two men firing from behind a turnip heap, the one wearing the ordinary uniform cap and the other a sniper's robe suitably garnished. In each case the photographs were taken at a distance of only 8 yds.

Disruptive painting, as a method of reducing visibility, has been alluded to in an earlier section of this article. Its simplicity makes a strong appeal to the imagination, and a large number of objects, including guns, were so treated. The colours employed were green, cream and brown, isolated from each other by thick black lines. The principle is that one or more of these colours is capable of merging into any surroundings, leaving the visible remainder as a number of detached patches of colour, thus breaking up the form of the object into a number of dissociated pieces. The contrasts in colour must be marked, and the patches large enough to be distinct when viewed from the appropriate distance; otherwise the colours will blend and, in consequence, the disruptive effect will be lost. An effect of texture is also essential to prevent reflection. In the case of guns, it was soon found that the wear and tear of active service caused the colours to lose their contrast and, consequently, their disruptive effect. The system was therefore abandoned.

In the case of large buildings and camps, the disruptive effect is nullified by their mass, heavy shadows and quite inevitable regularity of lay-out.

Camouflage Material and Its Production

By no means the least difficult part of the whole problem of camouflage was that of producing the material in sufficient quantities to meet the enormous demands. At first each position was treated individually as a separate problem, but it was very soon obvious that although this principle was desirable it was quite impossible, in view of the number of positions to be dealt with. It was evident that a system of standardization was imperative, in conjunction with some method of adapting the general to the particular. Standardized manufacture was therefore adopted. It was recognized that in certain cases standardization could not be applied; but experience showed that the proportion of such cases was small. In all cases the material was capable of some degree of adaptation to local conditions..

For gun positions, etc., three distinct media were furnished - fish nets, wire netting and scrim.

Fish Nets

The nets themselves were supplied from England. The size, 30 ft. by 30 ft., was fixed as being the minimum suitable for universal application; one or more nets could be easily joined if necessary. The nets were woven " square " in contradistinction to "diagonal," because the diagonal net closes when extended, cf. the principle of " lazy tongs." The meshes were 21 in. square. The outside was bound with strong cord to take the tension, and the whole was treated with a non-inflammable preservative. The garnishing of these nets has already been described. The nets were commonly used for all types of guns and were in demand because of their comparative portability.

Wire Netting was used in large quantities also, being stronger than fish netting, though less portable. For convenience in handling it was made up in rolls 30 ft. long, averaging 6 ft. wide, and was garnished in a fashion similar to fish netting, except that the thinning process could only be applied to the ends. In the field these rolls were joined up to suit the work they were intended to cover, and the thinning-out process was completed on the site.

Scrim, as already mentioned, by itself was mainly used on or near the ground and was issued in 30 ft. by 6 ft. rolls for a variety of purposes. Towards the end of the war, when night bombing became very persistent, scrim was used to cover aeroplane hangars (whose light-coloured roofs were very conspicuous at night), until coloured covers became the normal equipment of a hangar.

Colouration

In these three types four standard colourations were adopted, suited respectively to areas where the predominant conditions were: all vegetation, all earth, partly earth and mostly vegetation, partly vegetation and mostly earth. Both the scrim centres and the borders of strips were coloured in this way.

Observation Posts, etc. - Standardization of the exteriors of observation posts was not possible for obvious reasons, but the principle was applied to the bullet-proof interiors and other component parts. They were classified as: observer trees, periscope trees, parapets (sandbag or earth), portable O.P.'s. In addition there were many special situations provided for. Other standardized articles were: dummy attack figures, dummy heads, snipers' suits and portable covers for machine-guns - these last-named reversible squares of scrim 8 ft. by 8 ft., green on one side, brown on the other; made very light and portable for use in the field.

Manufacture

Although a description of the methods of production is beyond the scope of this article, discussion of the principles and practice of camouflage would not be complete without some reference to the important part played by materials, particularly canvas and paint.

Canvas is not an ideal material, being very susceptible to damage by weather, but it is easy to manipulate and is cheap. From the point of view of appearance, it is inferior to raffia, which, however, suffers from the hitherto insuperable disadvantage of inflammability. " Water" paints were generally employed for canvas for the reason that oil paints, which are more durable, are too inflammable, even to the extent of spontaneous combustion. This latter disability was the cause of disastrous fires where rolls of painted canvas were stored. Green dye proved too fugitive, but brown dyes proved satisfactory. Generally speaking, canvas and paint do not adequately fulfil the conditions of lightness and durability.

(F. J. C. W.) III. Naval Camouflage The painting of vessels of war with a view to reducing their visibility and so adding to their fighting value is by no means a modern development. The Romans are known to have painted their galleys; " seven kinds of paint were used, viz. purple, violet, yellow, two kinds of white, and green for pirates in order that their resemblance to the colour of the waves might make them less conspicuous." Camouflage on various lines but with the invariable idea of reducing visibility had been attempted in the British navy for many years before the World War. None of these schemes had met with any success, and each in turn had been abandoned after furtive trials. The two factors which led to this abandonment were first the failure to realize that anything in the nature of invisibility at sea is possible of attainment, and secondly the inability of the proposers of these schemes to provide definite instructions of a practical nature by which vessels could be painted with some degree of consistency.

The Board of Admiralty eventually adopted a partial form of camouflage by painting all vessels a light grey as opposed to the black hulls and light upper works previously in force. But even this simplest form of all protective measures was somewhat haphzard in application, since the individual vessels of a squadron varied considerably in colour, ranging from a light bluish grey to a dark slate according to the ideas of the commander.

It was not until 1917, during the height of the submarine peril, that a practical scheme having a definite end in view and formulated on scientific lines was put forward and officially adopted by the British authorities. This scheme embodied entirely new ideas on sea camouflage, and was rescued from the early disease which had attended all its predecessors by the fact that the proposer was able to supply designs to scale in large numbers, all bearing out a central idea. It was called for distinction's sake in official documents " Dazzle Painting." The sole object of dazzle painting was so to distort the normal appearance of a vessel that her actual course became a matter of doubt in the mind of a submarine officer, the estimation of a vessel's true course being the prime factor required to ensure successful attack.

Dazzle painting was intended primarily for application to merchant ships. These vessels were in far greater need of protection than warships owing to their slow speed and vulnerability and also from the fact that the enemy were making a concerted attack on England's supplies of food and materials essential to the conduct of the World War.

Warships as a rule possessed high speed and were moreover protected by destroyers, a type of vessel which while being the most deadly opponent of the submarine was comparatively immune from attack. A certain number of war-vessels were however dazzle-painted. These were chiefly ships engaged on convoy work, although a certain number detailed for special duties such as mine-laying and patrol service found this special form of protection of valuable assistance.

At first sight it would appear impossible to treat a vessel with paint in such a way that an experienced seaman could be deceived as to her actual course, but dazzle-painted ships proved that this could be done. Juxtaposition of violently contrasting colours, black and white predominating, combined in accordance with the laws of perspective, could make it extremely difficult to judge the accurate inclination of a vessel even at a short distance.

In the early stages of dazzle painting a large range of colours was employed to achieve the end in view. Experience showed that this could be attained by a much smaller number, and towards the end of the war the principal colours in use were black, white, and blue, these being employed in varying intensity.

Another factor which led to the simplification of the colours used was the knowledge that the German naval authorities had introduced the use of colour screens in their submarine periscopes with a view to reducing the camouflaged ship to a silhouette, and so neutralizing the effect of the colours used. These screens however had no effect whatever on a design depending solely on black, white, and blue for its contrast. Shortly after its adoption by the Admiralty dazzle painting was incorporated under the Defence of the Realm Act and the whole merchant service was ordered to be painted. Numbers of war-vessels operating with merchant ships were also painted: these comprised chiefly convoy cruisers, sloops and destroyers. The 10th Cruiser Squadron, engaged in blockade duties and composed entirely of large merchant ships, was also painted. These vessels were specially liable to attack, being at sea for long periods in submarineinfested zones and constantly under slow speed or altogether stopped for boarding purposes.

On the introduction of the scheme a considerable volume of maritime opinion was directed against it from lack of a proper grasp of its objects and because it appeared to render a vessel more conspicuous than was the case when painted grey. In point of fact at the date of the submission of the scheme the proposer, who was on patrol duty in the channel, had noted that all transports were painted a dead black from water-line to truck. The opposition, however, rapidly disappeared as soon as the objects of the scheme were thoroughly grasped and the rapidly increasing numbers enabled seamen to judge for themselves the difficulties of accurately estimating the accurate courses of dazzle-painted ships met with at sea.

The organization for producing designs in great variety and arranging for the rapid application of the designs to large numbers of vessels of great diversity of types was as follows: The mercantile marine was divided into 37 classes of characteristic types. For each type a small wooden model was made to scale and on this model a design was painted in wash colours. It was then carefully studied in a prepared theatre through a submarine periscope with a view to obtaining the maximum distortion. Behind the model were placed various sky backgrounds, the conditions of an average day at sea being obtained as nearly as possible. The model. was slowly revolved on a turntable and observed from every point of view, any necessary alterations and additions being made until the distortion became such that an independent observer found it a matter of considerable difficulty to judge its orientation.

The model was then handed to a trained plan-maker who transferred the design in colour to a 1-16 in. scale plan on white paper showing port and starboard side (see Plate I.). Each colour on the plan was numbered to conform to the official colour charts, which gave a complete range of all colours used in dazzle painting (see Plate II.). It was one of the important factors essential to the success of the scheme that these colours should be rigidly adhered to by painting contractors.

The Dazzle Department was represented at all the principal shipping ports by one or more officers specially trained for the work. These officers were responsible for the issue of plans and the supervision of all ships painting in their districts. This work entailed a great deal of highly skilled supervision, as the actual painting fell upon the local painting contractors, whose men were entirely new to this kind of work. With the rapid expansion of the scheme however, upwards of loo vessels were sometimes in hand at one port, difficulties were overcome and the work proceeded smoothly.

Soon after the establishment of the Dazzle Department, inquiries were made by the Allied maritime governments as to the efficacy of this new form of defence against the submarine. The French Ministry of Marine attached three officers for training under the new scheme and shortly afterwards set up a similar department in Paris. The U.S. Navy Department asked that an officer might be sent to Washington; shortly after his arrival a dazzle department was formed to deal with U.S. shipping. The Belgian Government arranged for all their merchant vessels to be dealt with directly in the British department. Complete sets of plans were forwarded to Italy and Japan.

All U.S. destroyers and other patrol vessels in European waters were painted from plans supplied from the British department. The number of vessels saved by this device can never be definitely ascertained as it cannot be known how many attacks were broken off by enemy submarines owing to a wrong position having been taken up as a result of inaccurate estimation of the vessel's course due to the dazzle painting. But the rapid expansion to all Allied merchant shipping showed that the authorities were satisfied that it played a great part.

Approximately 4,000 merchant ships were painted and upwards of 400 war-vessels engaged principally in convoy and patrol duties were also painted. The total cost of painting amounted to some 2,50o,000. (N. W.)