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542 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 camou- flage on the other hand the difficulty had to be faced, and an inge- nious 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 them- selves cast little or no shadow.

The above outline will suffice to give a general idea of the rela- tion between animal colouration and camouflage. But it should be added that the camoufleur has much greater difficulties to con- tend 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. (J. C. Mo.)

II. MILITARY CAMOUFLAGE

The word " Camouflage, " in the broad sense of military de- ception, 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 successful!}' employed to mis- lead an opponent on occasion ever since guns became a normal part of military equipment. Washington Irving in his Conquest of Gra- nada 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 Khaki (see 15.770), and after the experience gained in the South African War, when the importance of concealment came into great prominence, the Brit- ish and most other armies soon adopted dust-coloured, light-blue, grey, or grey -green uniforms.

Shortly after the South African War, experiments in the dis- ruptive 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 pro- longed 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 rely- ing 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 re- sources 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 or- ganized 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 occupa- tion of localities by troops and guns is fleeting, and, in conse- quence, 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 docu- ments 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 many specimens of this mate- rial were captured for the first time, together with numerous exam- ples 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.

(i) Camouflage against " Air Observation." The purpose of camouflage is to render objects indistinguishable, or un-