In this sense Napoleon was served by an intelligence officer of the first class - Col. Bader d'Albe, unknown to fame save as a cartographer, but in fact the one assistant who was present when Napoleon arrived at his great decisions in the field. Lying prone on the outspread maps, compasses in hand, with D'Albe at his elbow to inform him either as to topography or as to the enemy's dispositions and order of battle,' Napoleon could handle a changing situation day by day with all the certainty that the means of communication of his day allowed. It has recently been remarked that, to a Napoleon, an intelligence staff is more indispensable than the operations staff, and the remark is historically justified by the facts. For an operations staff is the product of a military system - that of Germany - in which the commander-in-chief is a sovereign who may not possess the qualities of command but yet must command, and it has developed because the growing intricacy of operations detail has compelled an increase in the number of workers who collaborate with the normal commander-in-chief. A saying of Foch is illuminating in this connexion. The great French marshal, asked how Napoleon would conduct the western front campaigns, replied:" Were he to return he would say ` you have weapons, numbers, communications, aircraft, transport such as I never possessed. Stand aside, all of you, and I will show you.' But, now as then, he would have taken care to have his Basler d'Albe at his side."In so intimate a union between the master of operations and the intelligence officer, it may be assumed without direct evidence that a man whose military judgment was matured by the unique experience of watching Napoleon's brain arrive at 1 Basler d'Albe kept a card index of enemy formations and units.
conclusions, and following his thoughts so as to be ready to supply the data on which they fed, must have added the function of" interpretation "to those of collection and sifting.
Napoleon was his own operations staff, and Basler d'Albe, in his own person also, was the intelligence staff. But while, as above mentioned, the operations work of a Napoleon came, in the middle of the 19th century, to be devolved upon an organ known as the general staff - there was no collateral development on the intelligence side. It is true that within the general staff a branch was usually set apart for intelligence work, and that such organizations of secret agents as existed were controlled by the general staff. Moreover, the study of foreign languages came to be regarded as a valuable element in a staff officer's equipment. But these things did not amount to providing the command (or the operations staff, which is often the command in commission) with the organ which should play Basler d'Albe to their Napoleon. France, with its" Deuxieme Bureau,"came probably as near to that ideal as any country, but the Deuxieme Bureau was discredited and shaken to its foundations by the Dreyfus affair. Moreover, a new doctrine of the relations between operations and intelligence, to be discussed presently, was set up about 1912, which tended to impair its usefulness still further. In Great Britain the reorganization following upon the Esher report in 1904 provided that the directorate of operations on the general staff should deal, section by section, with intelligence and operations together; thus, the section charged with preparing plans of operations against, say, Turkey was responsible for all intelligence concerning Turkey. In the field organization, both before and during the World War, sufficient officers were allowed on the staff of each formation for one to devote himself principally to intelligence work, and at G.H.Q. there was provided a" brigadier-general intelligence "coequal with a" brigadier-general operations."But any real specialization of function which grew up in the war was due rather to the immense and unforeseen volume and complexity of the information to be handled than to any change of doctrine. If, in the higher staffs, officers were engaged on intelligence work to the exclusion of every other activity, on the lower staffs it was not so. To the very end of the war the theory that, in a division, a G.S.O. 3rd grade (Intelligence) was the understudy of the G.S.O. 2nd grade (Operations) was rigorously maintained, and an" intelligence officer "so called, who was expected to be nearly as familiar with doings on the German side of the wire as an operations staff officer with those on his own side of it, was looked upon as a technical assistant to the general staff rather than as a member of it. The fact that the subjects on which information was required were immensely extended in the war, did not, and quite logically did not, involve any change of doctrine any more than the appointment of a dozen extra foreign correspondents to a newspaper staff affects the distinction between the news-getting and the editorial functions.
But the inclusion of" interpretation "as a function of the intelligence staff - de facto if not de jure - marks a difference in kind. Once this is admitted and carried to its logical conclusion, certain officers are told off to live, mentally, in the enemy's camp, to form and to convey to the commander working ideas of the opponent's life, mentality and routine, to vivify the specific facts gleaned by them or by others. An epigram current in the British intelligence service during the war admirably sums up the new role: -" The intelligence officer's job is to command the enemy's army."This is what interpretation implies. The facts have to be given not merely a meaning, but their true meaning, or as near an approximation thereto as possible. It is an old, but frequently misleading, maxim of war that a commander should ask himself what he would do if he were in the enemy's place. The real question is: How will the situation strike the enemy, given his organization, upbringing, habits of mind and predispositions?' If, for example, in the third week of Aug. 1914 Hindenburg and Ludendorff had acted on the supposition that the enemy would do what they in his place would do, Tannenberg would probably never have been fought, or, if fought, would have been merely a battle to gain time. As it was, when pros and cons were practically in equilibrium and the fate of East Prussia depended on the choice made, one thing turned the scale - a conviction derived from intimate knowledge of the Russian army, that in spite of recent reforms and of the evident war-readiness of the enemy, slowness was an inherent character of his leadership. But for this, the decision to leave a mere handful of cavalry in front of Rennenkampf's advancing army, and to concentrate every available rifle and gun against Samsonov, would have been simply trusting to luck, and although luck must always play a part in war, it is the art of command, whether the command be personal or in commission, to reduce this part to a minimum.' To answer the question, then, the commander and his operations assistants must have an intelligence staff which will constantly supply them with a picture of enemy movements, positions and intentions. To construct this picture a high degree of military training is necessary, especially in the senior ranks, and the personnel in these ranks must be drawn from the same sources and trained to the same level as similar personnel on the operations staff. But, given this equipment, the intelligence staff officer need have little knowledge of current events and intentions on his own side. The fewer his prepossessions the better.
On this point there has been in the past not a little controversy. In the French command regulations of 1913 it was laid down that the duty of intelligence was to seek for information on the topics and in the directions indicated by the command. In all armies, this principle was accepted so far as cavalry reconnaissance was concerned, the capacities of that arm, and its fragility (exhaustion of horses) made it essential that its activity should be directed to obtaining definite answers to specific questions. The same applies to some extent to informationgathering by other front agencies. And so far as they are concerned the wisdom of the doctrine is unquestionable. In a local tactical situation the presence of enemy forces in certain positions, or their movements in certain directions, can as a rule bear only one meaning. But it is altogether different in the case of groupings and movements of major importance. Here data, even if complete and still more if incomplete, maybe wholly misleading unless interpreted by men both qualified in respect of military judgment and also free from preconceived ideas. Instead of placing the intelligence staff in the position of the enemy, with instructions to compile a picture of his grouping and intentions, the doctrine embodied in the French regulations fetters it by compelling it to start from prepossessions. It is to this principally that must be attributed the miscalculations of the French intelligence in Aug. 1914 - miscalculations that were nearly fatal to France. It was assumed a priori that only firstline troops would be employed by the Germans, and the Deuxieme Bureau directed its efforts to identifying the various active army corps as they stood in the strategic deployment. In this it succeeded, but the presence of many duplicate corps of reserves, bearing the same numbers and assembled in the same areas as their parent active corps respectively, passed unnoticed Thus the strength of the enemy's troupes de choc came to be estimated on the eve of battle at 40 divisions, whereas in reality there were 68.
When the intelligence staff is regarded as the mirror of the enemy the risk of such miscalculation is minimized. The mirror may be dark at times, and a priori reasoning by the command may then be necessary to supplement the picture, but that is a very different matter from drawing a picture for the intelligence staff to fill in. One argument, and one only, in favour of coloured intelligence was and is tempting - the 1 As an example of the reverse, the battle of Worth in 1870 may be quoted. If, in the circumstances described in 28.834, there had been present on the German side any commander or staff officer with an intimate knowledge of the habits of the French army, the battle would never have been fought.
psychological. General Berth clot has admitted that in the information given by French G.H.Q. to subordinate commanders the enemy forces were sometimes deliberately understated so as not to alarm the recipients. Such a proceeding - the risks of which are obvious - is equally conceivable as between an intelligence staff and a command staff. But it is the less likely in proportion as the intelligence staff is allowed to disinterest itself in the events and intentions of its own side. And although it may sometimes be in the general interest that a subordinate's local fears should be overcome by means of a subterfuge, a G.H.Q. must always face the facts. That is the essential quality of its supreme responsibility. Correspondingly, the command is entitled to insist on the facts being presented to it. The intelligence staff need not of course produce at every moment the mass of small items on which its" appreciation "is based, nor should this appreciation be liable to be overruled by a different interpretation of the same evidence on the part of the command (herein its position differs from that of an operations staff). But it cannot expect the" appreciation "to be accepted unless it possesses the confidence of the command, and there is no surer way of forfeiting this than by crying" wolf "too often.2 In this modern conception of military intelligence it is evident that the chief of intelligence bears a responsibility that is only less than that of the commander-in-chief or his deputy, the chief of the general staff. The personal rank of the head of the intelligence branch may be high or may be comparatively low, the numerical strength of the organization that he controls may vary from a dozen or two to some thousands - not including" agents "in either case - and the scope of the work may be purely military and local or may cover almost the whole military, political, industrial and economic field as it did in the World War. But whatever his rank, his system and his scope in any particular case, his function is unlike that of any other branch of the staff. He".commands the enemy's army,"that is, he interprets to the best of his ability that independent will over which the commander-in-chief exercises no authority.
The collection, sifting and interpretation of data concerning the enemy's resources, movements and intentions constitute what is usually called" offensive "or" positive "intelligence. There is another branch of intelligence work known as" defensive "or" negative "intelligence, but which might more correctly be called counter-intelligence This consists in preventing the enemy from obtaining, or at least from gathering in, the data for his own offensive intelligence. Within its scope fall, besides the obvious task of detecting spies, preventive measures of various kinds such as the enforcement of discretion within one's own army, and the registration of aliens' movements. In some cases, as in Great Britain, the convenience of having all secret services handled by a single staff has produced the combination of counter-intelligence work with that part of offensive intelligence which operates by secret means. Collectively, this service is known in the British organization as Intelligence B or I(b), in contradistinction to Intelligence A or I(a) which obtains information openly and collates and interprets all" offensive intelligence "material however obtained.
trustworthy, and at the same time has to be synthesized in an atmosphere of hurry and high tension, and interpreted, often without waiting for checks and confirmations, for a commanderin-chief who may well hesitate to stake everything on its accuracy. Nevertheless, during the World War the service of military intelligence reached a level of accuracy and usefulness that it had never reached in any previous war. This success was due (a) to the rapidity of modern means of communication, (b) to the enormous volume of the data obtained, and (c) to the rapid development of aviation. These causes taken together both compelled and justified an elaborate organization of the intelligence service both in War Offices and in field armies.
In considering the organization it is better to ignore the distinction between War Office and G.H.Q., and to differentiate, instead, between the central intelligence system - of which certain branches and representatives live and work at G.H.Q., others in Allied and neutral countries and the rest at the War Office - and the field intelligence system. The central intelligence system in all cases carries out all the processes - collection, synthesis, interpretation - in connexion with the enemy's forces, recruiting and losses, internal condition and moral, economic condition, armament and equipment. When there are several important theatres of war, it is also the final focus of information, and interpreting authority, for the enemy's order of battle, and organization, distribution of force to the different theatres, inter-theatre movements, general plan of campaign, military moral, quality of troops, characteristics of leaders and tactical methods. It is, further, the authority responsible for passing information derived from one theatre to other theatres so far as it concerns them. To it belong all organs of the secret service and the counter-intelligence service - together known in Great Britain as I(b) - whether working in a theatre of war or not. It is an open question whether counter-intelligence (which lives mentally on its own side of the line) and positive intelligence (which lives on the enemy's) should logically form part of the same organization, but it is clear in any case that all branches of intelligence which employ secret means of newsgathering should belong to one system, which is the central.
To field intelligence, on the other hand, belong essentially the study, within the theatre of war, of enemy plans, as revealed by his distribution of force, movements, and front and rear works. If the theatre of war is single, some functions normally" central "- such as moral, order of battle, tactical methods - may come within its scope. Indeed there may be campaigns in which field intelligence absorbs central intelligence completely. In the past, with imperfect means of liaison between home and headquarters, this was often the case even in European campaigns, while as regards warfare in undeveloped countries it is often so still. But in war on the scale of the World War, in which the front and the rear, the soldier and the citizen, the gunner and the scientist, react upon one another incessantly, it was imperative to organize the intelligence service - effectively, if not formally - on the basis of a central system for the whole and a field system for each theatre. This logical distinction does not mean that central intelligence and field intelligence operate in watertight compartments. Each is indispensable to the other in a dozen ways. For instance, at the very least half of the data used by central intelligence in determining the enemy's battle order are obtained by field intelligence, and central intelligence, through interrogations of rapatries and refugees, contributes essential details to the stock of field intelligence.
Field Intelligence
As the scope of field intelligence, in the narrow sense,
there remains the study of enemy plans and of the ground within its own theatre of war. To this the central intelligence system contributes all necessary battle order information synthesized and interpreted; topographical information as up to date as possible; the estimate that it has formed of the enemy's strength: the deductions as to the general intentions of the enemy that it has arrived at from studying his military, economic and political and moral conditions; and any technical matters of tactical importance, such as the probability of a new gas being used. But with all these aids, the task of field intelligence remains an exceedingly heavy one. It is concerned with the tactical situation of every part of the front, in detail. Trenches, dugouts, machine-gun emplacements, trench-mortar emplacements, battery positions have to be watched day by day fOr new work or for signs of evacuation. Rear areas have to be studied to discover the creation or abandonment of dumps, sidings, aerodromes and wireless masts and above all for indications of movement. An accurate picture in detail of the enemy's defence system has to be formed and information obtained to amplify or correct that already on the maps, as the basis of any local attack scheme. And, over and above all this, field intelligence provides, by means of its wire organs, much of the battle order and other material upon which central intelligence builds up its appreciations.
The organization of the field intelligence service, during the war period, was improvised, and suffered from the defects of improvisation. Intelligence staffs were never truly separated from operations staffs, and within the intelligence branch itself there were distinctions of status and prospects between" staff officers "proper and" intelligence officers "which were all the more invidious as staff status was given in very numerous cases to officers engaged in administrative work pure and simple. In the case of the French army, intelligence officers were not even given military titles, being styled" interpreters."But apart from questions of status, the tendency to multiply intelligence staffs at every headquarters was wasteful of personnel and energy, led to much duplication of work and also to unnecessary circulation of the raw material of intelligence. In the lower formations the daily intelligence summary, which dealt with its own side's operations as well as with the enemy's, carne to be regarded as an internal communiqué or local newspaper, instead of being treated as the raw material which in fact it was. Aeroplane photographs too, which require a special expertise to make them practically useful, were distributed broadcast. Intelligence should, of course, issue the results of its work to every branch and person concerned, but the processes by which it reaches these conclusions, and still more the undigested material on which these processes are set to work, are useless and mostly quite uninteresting to the soldier in the line.
The term Ground Reconnaissance, formerly confined to reconnaissance of terrain as against reconnaissance of enemy movements, is now used to denote reconnaissance of any kind carried out by troops on the ground as against that carried out by aircraft. Though the advent and perfection of the aeroplane have revolutionized the art of reconnaissance, the necessity for reconnaissance on the ground has not disappeared, for the aeroplane has its limitations and there is much information which can only be obtained by troops working on the ground. An aeroplane photographic reconnaissance will enable a pictorial view of the country to be got in a short space of time, and these photographs, especially if the country has previously been mapped, will be very valuable; but of such details as the configuration of the ground, the practicability of roads, the depth of streams, the penetrability of woods, the aeroplane photograph will give no information at all, or at best information which can be obtained more certainly by reconnaissance on the ground. Before an attack invaluable information may be and is obtained by air reconnaissance of the positions to be assaulted, but it is still necessary for the forward troops to push out patrols to reconnoitre the ground and for personal reconnaissance to be made by those to whom the actual attack is entrusted, though they will be able to reconnoitre the ground to better purpose and with greater safety from the knowledge that has already been obtained by air reconnaissance.
Reconnaissance differs in its methods in open and position warfare, but in both the principles are the same. It has two objects: to prevent the enemy's obtaining information about the belligerent in whose behalf the reconnaissance is made - that is, protective or negative reconnaissance - and the obtaining of specified information about the enemy, which may be called active or positive reconnaissance. In open warfare the first is carried out by the screen either of cavalry or infantry or both which is sent out by the commander to deny the enemy observation of the movements of this main body; in position warfare by the first-trench system, or according to later ideas by the organization of a forward zone masking the" Battle Zone "where the real resistance would be put up. The second object of reconnaissance is brought about by the driving in of the enemy's protective system and so obtaining contact with his main body, or by the employment of patrols and scouting parties, whose object is to obtain timely information with a minimum of deployment. Position warfare involves a state of continual contact, that is, the protective screens of both armies are always facing each other at close quarters. In open warfare, especially when armies are operating over large extents of territory, manoeuvre is necessary if the protective screens, to say nothing of the main bodies, are to come into contact with each other.
The objects of ground reconnaissance are varied. It may be purely topographical, that is, it may be concerned with the acquisition of unmapped information about the ground in anticipation of movement over or occupation of that ground. It may be tactical (that is, it will endeavour to discover the positions held by the enemy and the strength and distribution of this defence), or it may be concerned with the obtaining of" identifications "(that is, information about the troops of the enemy in line, either by the capture of prisoners or of documents) .
Air Reconnaissance, in spite of certain limitations, has many advantages, however, over ground work. One of the latter is its greater freedom. Machine-guns impede ground reconnaissance much more effectively than A.A. weapons and hostile aircraft impede air reconnaissance. Moreover a greater area of ground can be covered in a shorter space of time. By means of messages dropped at prearranged stations or by wireless, information can be sent back in a minimum of time; and, since the observer in an aeroplane sees the ground as a map and so can easily" pinpoint "what he sees, positions of troops, etc. can be given with a greater accuracy than is possible to the ground observer. In the watching and control of enemy reserves aircraft can perform services which are not possible for any other means of reconnaissance. Contact with the enemy cannot at present be obtained by the use of the aeroplane; but, owing to the fact that the aeroplane can penetrate the protective screen of the enemy and observe the movements of his main forces, a type of contact can be obtained from the air with greater efficiency than from the ground.
The use of the aeroplane camera makes air reconnaissance even more valuable than it would otherwise be. Owing to the height and also the speed of the aeroplane, many details escape the eye of the keenest observer. The use of the camera almost eliminates the personal factor. All that is necessary is that the observer should be able to manipulate the camera and have sufficient knowledge of the map to take the photographs at the correct moment. The image of the ground on the plate is very quickly developed and printed, and studied under favourable conditions away from danger of enemy fire. Aeroplane photographs became more and more important during the World War. Cameras were improved; the men whose task it was to interpret the photographs after they were taken became more and more expert; and the possibilities of their work became more fully realized. At first several difficulties had to be faced, the chief of which were mist and vibration. The mist in the atmosphere rendered the photographs taken so indistinct as to be almost useless. But by the use of filters (that is pieces of tinted glass or celluloid placed next to the camera lens), it was found that photographs could be taken through a mist which the human eye could not pierce. Vibration caused more difficulty. The danger that, through the throbbing of the engine, the camera might be tilted while the photograph was being taken, was finally eliminated by the use of rubber cushions which absorbed the vibration of the aeroplane.
In addition to the important photographic reconnaissance, other types of air reconnaissance were used during the war. Each dawn and dusk, and at other times when conditions made it necessary, reconnaissances were carried out by powerful machines. Their principal duties were to keep close watch of road and rail movements of the enemy. Since these movements mostly took place during the night, dawn and dusk were the times when results were most likely to be obtained. The dayto-day results of the reconnaissance were plotted in" activity maps "which made it possible to gauge the normal movement in any railway line on the battle-front, and so, with the aid of collateral information, to establish conclusions as to significant abnormalities. Another type peculiar to position warfare was the trench reconnaissance. This was carried out by an aeroplane flying low over the trench lines. It had for its object the discovery of the state of the enemy's defences, what portions of the line he was holding, the location of machine-guns and trench mortars, and all those numerous details a knowledge of which was required in carrying out an attack or raid on strongly organized positions.
" Artillery "air reconnaissance was primarily intended to counteract the effects of the enemy's artillery fire on one's own troops. Flying backwards and forwards along the battle-front, the airman watched carefully for the fire of enemy batteries. When a battery opened fire, its position was signalled by wireless, and it was promptly engaged by the counter battery.
One of the chief difficulties with which a commander has to contend during an attack is the difficulty of knowing quickly how far the attack has succeeded and to what distance his troops have penetrated the enemy lines. The aeroplane therefore has a useful function in maintaining contact with attacking troops. In the World War machines carrying out this duty were called" Contact Patrols."They were not intended for fighting purposes, but to determine the position of the attacking troops. In open warfare the aeroplane landed in or near the forward positions and received an account of the situation from the troops themselves. But when this was impossible prearranged signals of various kinds were given by the foremost troops to show their position. A good airman worked without any help from the ground troops. He would fly at a low altitude, sometimes as low as so ft., along several miles of front, and place correctly the position of all the forward troops. To determine the position of the enemy and also to discover in what direction counter-attacks were maturing the airman had to rely on his powers of observation. Such work was often very dangerous, since it necessitated flying low over the enemy. Various signals were devised by means of which the aeroplane could inform the infantry of an expected counter-attack. The duty of watching for such threats was sometimes assigned to a separate counter-attack patrol; but more usually it fell to the contact patrol itself. Having obtained his information the pilot's object was to give that information as speedily as possible to those who needed it. He did this as a rule by dropping a message or a marked map at a prearranged station; or he landed at a headquarters and explained the situation in detail to the commander; or he returned to his aerodrome where an officer of the intelligence staff interrogated him and telephoned or telegraphed his information to those whom it concerned.
Detecting A gencies. - Differing from reconnaissance principally in the absence of" contact,"but otherwise analogous, are those means of obtaining information which may be called collectively detecting agencies. These are visual or instrumental, and in some cases a combination of the two. V'sual observation for intelligence purposes differs from the ordinary watching duties of sentries in that it is an organized service - partly or wholly under intelligence control - for the observation and recording of all enemy activity within the range of vision of the front-line observation post, the tree or belfry behind the line, or the captive balloon in which the observer is stationed. Its records go into the common stock of tactical intelligence material, its work is facilitated by a special equipment of maps, telescopes, etc., and its various elements are so placed and coordinated that the exact location of the enemy activity recorded (e.g. digging) can be fixed by intersection. In its most precise form, observation becomes" flash-spotting,"that is, the location of an enemy battery position by simultaneous observations of a gun-flash from two, three or more visual posts provided with goniometers and connected electrically with a central where the result of the intersections is plotted. Flares, Very lights and searchlights to facilitate night observation, are aids to defensive sentries, not to" positive "intelligence.
Detection by instruments (other than the usual flash-spotting in which, after all, the quickness and accuracy of the observer is the main thing) is automatic. Instruments are disposed to receive, transform and transmit impulses from outside, and the human element (except in instruments of the geophone class used in mining) is only introduced at the" central "or exchange station - i.e. at the point of synthesis, and not in collection. Such are sound-ranging installations, wireless interception and direction-finding apparatus, and electrical listening-posts. All contribute to the common stock, and each affords collateral checks - called by the French recoupements or" intersections "- on the data provided by the rest, or by reconnaissance proper, or from other sources.
Enemy Works and Installations
Information about the defensive system and the organizations of the enemy is obtained from reconnaissance and to some extent from (b) sources, but the most fertile and certain source of information is the aeroplane photograph. Aeroplane photographs are of two types, the oblique and the vertical. Those of the first type are taken from heights of 200 to 1,000 ft. with a tilted camera. Taken at a i,000 ft. they show the ground as it would appear to an observer from the top of a mountain. Not much detail is visible, but an excellent idea of the general lie of the land is given. Taken at a lower altitude, such details as trench construction, loopholes and machine-gun emplacements, entrances to dugouts, roads, trees and hedges are apparent. The more important type of photograph, however, is the vertical, that is, a photograph taken from directly above, with the camera pointing straight downwards. The appearance of objects on the vertical photograph is stranger, and puzzling to the uninitiated student. All objects are seen from above, so that only their tops and shadows are visible. Everything is seen in plan as on a map and to be able to appreciate a vertical photograph one must, so far as circumstances permit, accustom oneself to see the ground from above, and in any case cultivate a sympathetic understanding of maps as maps.
Vertical photographs may be taken at almost any height. If taken too low the result may be blurred owing to movement, 1 In the earlier campaigns of the war, strange to say, messages in clear were sent on several important occasions.
but clear photographs may be obtained from 2,000 to 20,000 ft. The scale of the photograph varies according to the height at which the photograph is taken and the focal length (that is the distance between the lens of the camera and the photographic plate) of the camera used.
Different types of cameras are used according to the scale of photograph required. If a forward trench system is required to be photographed a short focal-length camera (say 8 in. or 10 in.) will be used on a machine flying at a low altitude (say 6,000), so as to get a photograph on a comparatively large scale. On an extensive photographic reconnaissance of an area some miles behind the line, where the object is to get photographs of a large area, not for study in detail, but to discover what constructive work is engaging the enemy, a" wide-angle "type of camera (i.e. a camera of short focal length, but, since the photographs are taken at a great height, [15,000 ft. to 18,000 ft.,] on a full plate, show a large area on a small scale) is employed. With this type of camera a larger area can be covered in a short time. If these wide-angle photographs show details of which a more thorough examination is desirable, large-scale photographs can be taken from a height of 15,000 ft. and more with a long focal-length camera (20 in. or even 48 in.) which will show clearly small dumps of material or even the actual barrels of guns.
In working on aeroplane photos there are two stages, the reading of the photo (often called interpretation, though the word is avoided here as having been used in another significance in this article) and its" annotation,"that is, the redrawing of its indications in map form for the use of the army generally.
Aeroplane photographs record colours and accidents of the ground (such as bare earth, vegetation, woods, etc.) in terms of light and shade. The ground appears as a simple or complex pattern, in black, grey and white. Though the aeroplane photographic plate is affected by colour, that effect is not so marked as the effect of texture and shadow. For instance, a stretch of dry earth which to the eye appears dark will appear almost white on the photograph. The reason for this is that being smooth it has no texture or contained shadow, and consequently reflects light. Vegetation, on the other hand, which to the eye appears light will photographically be at the dark end of the scale because of its texture and contained shadow. It absorbs rather than reflects light. So when the nature of objects in an aeroplane photograph is to be determined colours must be judged principally in relation to texture. The ground must be visualized vertically not obliquely.
The reading of aeroplane photographs, which necessitates a keen, trained eye, consists in the" spotting "of the numerous details which the photograph contains; its annotation, which is in effect the labelling of the various objects shown, presupposes ability to appreciate these details and their relative importance in the enemy's system of defence and organization. When a detail has been discovered, the examiner of the photograph must decide its probable nature and its role and importance in the enemy's system of defence, offence or supply. Details are often very similar in photographs and their nature can only be discovered by considering them in relation to their position and the surrounding details as well as in relation to the current tactical practices of the enemy. The reading and translation of aeroplane photographs indeed is not a solitary science. The interdependence of all branches of intelligence work has already been emphasized and -certainly this is no exception. Many details can be seen on photographs and their nature determined from photographs alone; but there is much that will be doubtful and must be reexamined in the light of prisoners' statements, ground and air observations, captured documents and captured maps. Conversely, the aeroplane photograph may supply missing links in a chain partially established otherwise.
Unlike photographs taken obliquely, which convey something to the merest novice, the vertical photograph must be carefully studied before it reveals its secrets. Only the tops of objects and their shadows are visible and it is only through the latter that the nature of many objects seen on a photograph can be determined. All objects have shadows. On a dull day they may not be apparent to. the naked eye, but they always show clearly on a photograph. The first step, therefore, in examining a photograph is to discover from what direction the light is coming, that is, the position of the sun in relation to the photograph. This can always be discovered by examining the shadow cast by some known object such as a house or a tree. By a study of shadow not only can we discover whether an object has height or depth, but we can also get much valuable information about its shape and size. Thorough familiarity with the effects of shadows is in fact an absolute essential to the correct study and easy appreciation of aeroplane photographs.
Photographs must be examined systematically, detail by detail, and frequent comparison of photographs taken on different dates made. If a day's photographs are examined alone, many small details will be missed, and it is impossible to follow progress in the construction of enemy works, and to note increase and decrease in the size of enemy's dumps and aerodromes, etc., so important in studying enemy intentions.
Aeroplane photographs are of greatest value in position warfare. In open warfare their use is not so great. Armies advance over areas of so great an extent that it is often impossible to take photographs and get the information from them before the area photographed has ceased to be of interest." Moreover, the defences conducted in open warfare are usually of so simple a nature as not to be visible in photographs. Machine guns are concealed in hedges or in the windows of houses, guns are fired in the open from sunken roads and the edges of woods. Protection is obtained by the utilization of natural cover. Such positions if they were occupied for any time would (unless elaborately camouflaged) betray themselves by the tracks made by men or vehicles approaching them; but if they are only occupied for a short period these tracks do not form. In open warfare therefore much more valuable results are obtained from airmen's reports than from their cameras. It is only when the enemy makes a stand for a few days on a definite line that photographs become valuable. During the first part of the German retreat from the Somme to the Hindenburg position in March 1917 air photographs were of little value. When however the British troops were held up by an outpost line in front of the main Hindenburg position photographs again became of use. On one occasion photographs were taken of a temporary enemy position, the photographs were brought back, developed and printed, and the results delivered by aeroplane to the divisional commander on that front in about an hour and a half. During a retreat in open warfare photographs can be used in watching the pushing forward of the enemy's communications and aerodromes, and during an advance in discovering what demolitions he has carried out.
We must now consider the tactical use of photographs. At the battle of Neuve Chapelle (1915) the maps used for the attack were simply ordinary topographical maps, with the enemy positions roughly marked. If defences are not of an elaborate nature, such a map may be sufficient. But when an attack is being made on a defensive system elaborately organized and several miles in depth, something more exact is necessary.
First of all thick wire entanglements must be faced. When these entanglements consist of several rows, each row from 20 to 50 yci. deep, wire cutters are useless, and gaps must be made either by artillery or tanks. In either case, for the ranging of the guns or for the drawing up of the plans for the tank attack, an accurate map of the wire entanglements is necessary. Numerous trench lines must be captured, dugouts both in the trench lines and in the terrain between the lines must be dealt with, machine-gun emplacements must be captured, and special arrangements must be made beforehand to subdue strong points of resistance, redoubts, fortified woods, farms, quarries, etc.
make the careful preparations necessary for an attack on such a position, not only the commander, but also his subordinates, must possess an accurate map of the position, which may be, and in the latter part of the war was, so deep that ground observation of its real defensive heart, the "battle zone," is impossible. The information then must come from the air, and moreover, though a competent airman may make valuable observations, the only means of plotting that network of trenches and other defensive organizations on to the map is by means of the aeroplane photograph. This may be defeated in some details by effective camouflage or by the successful use of natural cover, but in general an accurate map of the enemy's defences can be constructed from it - or rather, them, for a particular photo is or should be only one of a series which show the changing aspect of the ground as man's works are superimposed on it. Besides trenches, wire, and close defence positions of all sorts, the camera attacks the enemy's artillery positions. In some cases innocent ground begins, in succession photos, to show works, tracks and the like, until it becomes so definite that the balloons and the sound-rangers and flashspotters only confirm what is already certain. On the other hand, photo deductions may be doubtful or even impossible till the battery reveals itself to the other agencies by coming into action. In either case the work of the camera continues in aid of the artillery. Amongst the most important services rendered by the air photograph is that of recording the effects of bombardment upon battery positions, trenches, wire, strong points, dumps and communications.
Photographs a re also of value in studying enemy organizations, roads and tracks used by the enemy, billets and positions of reserves, signal communications, buried cables, air telephone lines, light signal stations, railways (normal and light-gauge), unloading stations, ammunition and supply dumps, stations and railway sidings, hospitals and aerodromes.
(C. F. A.; F. C. H.) (C) Secret Service and Counter-intelligence. - The section of military intelligence known in Great Britain as I (b) is charged with two functions somewhat opposed in character, but having this in common, that the methods employed in each are, generally, secret. This factor makes it difficult to submit those functions to public dissection except on general lines; what follows, therefore, is confined within those limits.
Broadly speaking, the duties of Intelligence (B) are: - (r) Offensive, in the acquisition of information as to the enemy's military resources, numbers, plans, movements and dispositions, by means other than those employed by I(a), which are identifications by contact; examination of the enemy and other press; scrutiny of captured documents and prisoners; air reconnaissance and photography; sound-ranging and other means. (2) Defensive, in the prevention of the acquisition by the enemy of similar information about our own forces. These together make up what may be described as Secret Service, and both involve the use of secret agents and secret methods.
Apart from the close connexion between them, the knowledge and experience of enemy methods gained in either sub-section is so immediately beneficial to the other that the functions of the two sub-sections are complementary and indivisible. They should, therefore, be controlled by one directing brain, especially in the field, where rapidity of action and of the circulation of information is essential. In peace-time at home, where the urgencies and difficulties of active service conditions do not arise, separation is permissible, though not generally desirable.
The offensive sub-section, to which alone the name Secret Service is popularly applied, can only be referred to in general terms. Its duties are similar in peace and war, and are directed towards the collection of information in enemy territory. For this purpose secret agents, or spies, have to be employed. The duties of these agents again differ but little in war and peace; but war increases their importance, and with it their difficulties and dangers. Whether they work as agents a poste fixe, like the agents of the notorious Stieber in France before and during the campaign of 1870; or whether they are sent on definite missions, or on general roving commissions, their objective is the same: information about the enemy. This objective is unaltered whether they penetrate into enemy territory through the ports, in the guise of peaceful neutrals armed with all the necessary papers, or whether they get there by other means. In war these other means may include penetrating the enemy lines, either in uniform or en civil, during the progress of an action; crossing the enemy lines and landing behind them in an aeroplane, either by the machine coming to the ground or by means of a. parachute; crossing similarly in a free balloon; or crossing a frontier guarded by sentries and electrified wire, by evading or killing the sentries, and climbing the wire in insulated boots and gloves. False papers, disguises, secret ink and all the other tricks beloved of the spy novel may form part of their equipment, but normally the less theatrical the spy the less likely he is to attract attention. In practice, the most dangerous and efficient spy is probably the least sensational in his methods; when arrested he invariably has all his papers in order and is the most plausible person alive. Men, women and even children of all grades of society and of all professions, may render services of varying degrees of importance, but all useful to a system of espionage. A spy system in war involves the employment of many thousands of persons: post-boxes, passeurs, contrebandi-stes and guides, train watchers, pigeon men, couriers, runners, reliables who will give shelter to agents and escaped prisoners, and notables who are capable of organizing a service. All have their respective parts to play behind the lines in modern war; and that part, far from being ignoble, may be, if actuated by patriotism, as noble, as dangerous and as heroic as any played in the armies in the field.
In spite of all the precautions adopted as the result of experience in the World War, the collecting of information is not the difficulty; that lies in the transmission of information when obtained. Over this subject a veil, unfortunately, must be drawn. Agents may carry pigeons to send back, or portable wireless sets for communication with their employers, and messages have been shot over a neutral frontier by crossbow. The use of directional wireless and ordinary vigilance and common sense soon lead, however, to discovery, and necessitate a change of venue for the agent, and the application of fresh methods after a short time. It is only necessary here to say that, contrary to a popular belief, signalling by an agent by any means from, or close behind, the enemy lines is almost impossible, except in open warfare. In trench warfare, even if it were possible, it would be of little use, as any information to be gained there is better obtained by other means. The agent's useful information is gleaned much farther back, and to get it he requires a thorough and careful training. Apart from the control of agents and of the administrative, financial and clerical questions involved in that work, the duties of the chief of this sub-section are to get information by all possible means. Amongst other methods employed in the late war was the dropping of pigeons by automatic release from free balloons. Advantage was taken of the wind's force and .direction to regulate their fall in or near any desired neighbourhood, and there they were picked up by the inhabitants. Following the instructions enclosed, the latter often gave rapid and valuable information as to the movements of the enemy.
Another form of activity on which agents may be advantageously employed is sabotage, i.e. the destruction in the field of bridges, telegraphs, lock gates and communications, and of munition factories and similar organizations in enemy home territory. The Germans are alleged to have employed these methods, even in neutral countries, where munitions and war material were being manufactured for the Allies. In the field, such work is most advantageously linked up with operations, either just before they begin or whilst they are in progress. If contemplated as a prelude to operations it must always be remembered that they may serve as warning of an offensive. In any event the officer directing such schemes must remember the probable consequences to an allied population in territory occupied by the enemy, on whom punishment will be visited. Sabotage of this sort is naturally easiest in crowded centres, where circulation is difficult to control; and although in war risk 10 human life, even of non-combatants, must in some cases be a secondary consideration, this fact alone requires that sabotage, if undertaken, should be expected to have definite results.
The duties of the other, the defensive, sub-section are popular ly described as contre-espionnage. Although the duties, as in the case of Secret Service so called, are the same in peace as in war, the machinery and methods vary considerably according to the conditions under which they are carried out. The varying conditions referred to are: (I) in home territory, in peace and in war; (2) in allied territory; and (3) in enemy or occupied territory. In the two latter cases war conditions only come into consideration.
Of these varying conditions the first provides, perhaps, the easiest problem. The contre-espionnage section commands, in peace and in war, all the assistance of trained police throughout home territory; of censorship; of port control; of hotel registration; of the erection of arbitrary barriers such as prohibited areas; and of all the preventive measures which may be the outcome of years of experience in combating enemy espionage under all conditions. Although Intelligence (B) in the field. in occupied territory would equally enjoy these powers, and, in addition, the arbitrary powers of the conqueror in the territory of the conquered, and would have the advantage of knowing that the whole population is potentially hostile, the machinery at its disposal to cope with it would be largely improvised and, therefore, at first, not so efficient. In allied territory the difficulties are greater, as it is the ally who, naturally, controls in his own home territory all the real preventive machinery. He is, in addition, possibly susceptible about interference with either his C.E. Organization, or with the native population. Under these conditions contre-espionnage is carried on largely on sufferance, and requires the exercise of much discretion and tact. It is necessary to remember that the object of contre-espionnage is, first and foremost, prevention. The catching of spies, interesting though it is, is entirely subsidiary; its principal value lies in disclosing the holes in the preventive net and in directing the attention of the controlling staff towards the proper remedies to be applied. In the zone of the armies the principal value of an efficient contre-espionnage system is a moral one. Troops and their commanders must be relieved of their anxieties about enemy activities in their midst; but from what has been written above it will be seen that those anxieties are often based on not very solid grounds, at least in trench warfare. Troops commonly attribute to an enemy secret service of any efficiency powers far beyond the capacity of any S.S. Organization. It is, of course, the effect of the unknown on mass psychology; but the influence on moral may be prodigious unless means are taken to check it.
From what has been stated it will be seen that the contreespionnage sub-section falls naturally into two divisions: (i.) the investigation of suspected cases of espionage, and (ii.) the control of the population. It is not possible to enlarge on the methods of investigation employed by a contre-espionnage service; although in general they resemble ordinary police detective methods, in details they differ widely from them. They require technical knowledge not usually possessed by ordinary police personnel; and even trained police-detective staffs require special training to be useful in contre-espionnage. In endeavouring to prevent the collection of information by the enemy's agents it is necessary to remember that this may he gained equally (i.) from your own troops and (ii.) from the civil population. The former may sell or convey information deliberately, but it is far more probable that they may convey it to the enemy's agents through their indiscretions. Investigation. of treachery requires no difference in treatment, whether it occurs among troops or civilians, and the question need not therefore be further examined. The problem of dealing with leakage of information through indiscretion, however, is a different one, and requires special consideration. "Leakage" may occur in several ways; gossip amongst the troops about impending operations, especially when they are on leave and out of the line; indiscreet conversations and messages on field telephone and buzzer; misuse of code in telegraph and wireless; marking of railway trucks, transport and billets, with inscriptions which give identifications of units; indiscretion in correspondence; careless handling of confidential papers and books; taking orders, codes, books, papers of any kind, even private letters, into the front line; wearing of regimental, brigade or divisional badges and markings, which reveal identifications, and many analogous ways. All these require special treatment. In many cases this demands merely vigilance to see that these things are not done, and that orders are constantly issued to the troops on the subject. Careless conversations on field telephones require "police" listening sets to record them, so that action may be taken against the offenders. Gossip about operations can be dealt with by the punishment of the offenders when caught; otherwise it is best coped with by the deliberate circulation of false rumours by Intelligence (B) through their police and agents. It is therefore one of the essential duties of the I(b) personnel that they should know what is going on amongst the men in their own army; from this it is an easy stage that they should keep the higher command informed of the moral, the grievances and the current rumours, not only of their own army, but also of the civil population and of the allied army and even amongst allied official classes. Every case of suspected espionage reported by the troops, even the most obvious cases of spy fever, must be investigated, and the results reported and circulated among the troops.
Finally, Intelligence (B) should advise the operations section of the precautions necessary in connexion with contemplated operations. This implies the closest cooperation with "0"; but it also logically involves the allocation to Intelligence (B) of camouflage, and similar mechanical methods of preventing the acquisition of information by the enemy. This was not the case in the late war; and this omission was, in the writer's opinion, a fault in organization.
The other sub-section of the contre-espionnage section is responsible for the control of the civil population. This involves a division of the area occupied by the army into zones for the purpose of the control of circulation, and control of the use of telegraph, telephone and other methods of communication, which might be of use to enemy agents. These restrictions vary in strictness according to their proximity to the fighting front, e.g. in the forward or army zone no access would be permitted to civilians of any sort; in the less forward zones civil liberties are less and less interfered with, until in the rearmost zone life may be almost normal for war-time.
The same sub-section is responsible for the drawing up and issue of all necessary regulations; the placing of the necessary port, frontier, railway, road and other controls at points of entry into the various zones. Here would take place the interrogations of persons entering or leaving the zone, the issue and visa of passes and the general supervision of civilian traffic. The form of all necessary passes (laissez-passers, sauf-conduits, protecting certificates, etc.) would be drawn up by the sub-section, in consultation with the provost-marshal's branch, and all arrangements made to fit in with his controls.
Card indexes must be maintained of doubtful persons, as full details as possible being given, to ensure their detention. Contreespionnage summaries and instructions must be issued from time to time, and provision must be made for the rapid circulation of such information to all controls and I(b) personnel. Amongst the other duties of this sub-section are evacuations of undesirables, prostitutes and suspects; supervision, licence and withdrawal of telephonic and telegraphic facilities to civilians, in accordance with military exigencies; interrogation of rapatries; preparations of lists of guides, notables and persons who may be useful in territory occupied by the enemy, in case of an advance; lectures to troops on precautions against leakage of information, even after capture; and all general precautions against espionage where it is a case of dealing with the population in the aggregate, as opposed to the individual.
Both sections must keep adequate and up-to-date records, carefully cross-indexed. In the case of the offensive Secret Service it is undesirable that the names, tasks and whereabouts of agents should be known to anyone but the officer under whom they actually work. Any such records kept must be in safes or strong-boxes.
As regards the machinery employed, both sections require large numbers of intelligence police. Their allocation in the zone of the armies is usually on an army, corps or divisional basis, i.e. certain detachments of officers and men (I.P.) are allotted to the headquarters of armies, corps and divisions. On the L. of C., or even in the army zone in the case of prolonged stationary warfare, they are best allotted on an area system, to ports, bases and areas. This has the advantage of acquainting the personnel intimately with the areas, the inhabitants and the special duties called for by special conditions.
One final duty remains to be mentioned - the conveyance of false information to the enemy. This cannot, unfortunately, be dilated upon. It is best undertaken by the head of I(b) himself, in consultation with as few persons as possible. The process, if it is to be usefully employed, involves the complete confidence in him of the higher command and a foreknowledge of their plans and dispositions. It requires, therefore, that he should be above all else a person of solidity and discretion. Apart from other qualifications there is indeed no room for the employment in Intelligence (B) of any person in any grade who does not possess these characteristics. (R. J. D.)
