1921] on Strategic Camouflage 311 



was assumed that after an elementary lecture or two based on text- 

 books of obscure origin, flying-men could read any war-time aerial 

 photograph. Whereas really its accurate interpretation depends on 

 deduction, based on a thorough knowledge of skiagraphy — the 

 science of light and shade — such as only an experienced painter could 

 be expected to have. 



War was revolutionised by the introduction of aircraft. That 

 had literally changed the point of view of our late enemy long 

 before 1914. 



The airship had called into being the perfected long-range 

 camera. " The other side of the hill " had disappeared. How much 

 the camera in favourable conditions could record had become one of 

 the main subjects of military research. 



If a few men crossed a field their movements could be traced ; 

 the work-worn earth around a camp or an aerodrome revealed its 

 character at a glance. The shadows cast by an upright structure, 

 nowever advertised with post-impressionist patterns, would do the 

 same for it. Night might not last long enough to obscure the 

 movements of an army, and if it did, and that army left the high 

 road, daylight would show up the silver trail of the great slug and 

 its whereabouts. If strategic intentions were in such circumstances 

 to remain a secret there was but one solution of the problem : 

 extensive overhead cover at selected points, on which should be 

 reproduced the character and the chief features of the ground it 

 concealed. And this conception was elaborated by the Germans, and 

 reached such a pitch of artistic plausibility that no abnormality in it 

 was detected by us. " The eye only sees what it knows." 



It must not be forgotten that the Germans had prepared them- 

 selves for some years, and were responsible for most of the innovations. 

 Our readers had had no first-hand experience. It was not till late 

 in 1915, when we brought down a German aeroplane and developed 

 the films found on it, that we realised the extraordinary capacity 

 of the camera. It was after that that our scientists got to work and 

 gave us photography as good as any the enemy had enjoyed. 



But curiously enough the official text-books on which the in- 

 struction of our readers was based contained photographs far too 

 detailed to have been prepared in war conditions with our earlier 

 ineffective cameras. 



Bernhardi wrote in his " Preparations for War," published in 

 1911: "We must develop the means of concealing our attacking 

 movements " — and they did. And we have learnt that the covering 

 art is not only the best of defensive expedients — for what is not seen 

 is the last thing to suffer — but also the most insidious and dangerous 

 of offensive means. It makes no noise, it gives no warning either 

 by smell or movement — in fact, it is the only concealer of move- 

 ment. 



On the Western front the proportion of German losses in killed 



