industrial condition. But the technical expert often needs the resources of a well-equipped proving ground or laboratory to enable him to carry out his examination, while the economist has to consider the items just enumerated in relation to other data not necessarily concrete, such as the enemy's internal and imported supplies of raw material, his manufacturing equip- ment and his industrial discoveries. But although it will be seen from the above that command intelligence belongs essen- tially to the central system, the role of the forward intelligence officer in collection of data is of prime importance since he alone can educate the soldier to realize the value of the " souvenir " and even of the unconsidered trifle that seems not worth picking up. It must not be forgotten that it is very largely on such things that armament intelligence has to work, guns and appa- ratus are not captured every day.
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 infor- mation 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 intelli- gence 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 indica- tions 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 intelli- gence provides, by means of its wire organs, much of the battle order and other material upon which central intelligence builds 'P 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, came to be regarded as an internal communique or local newspaper, instead of being treated as the raw material which in fact it was. Aero- plane photographs too, which require a special expertise to make them practically useful, were distributed broadcast. Intelli- gence 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 pic- torial 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 configur- ation 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 obtain- ing 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, ma- noeuvre 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 antic- ipation of movement over or occupation of that ground. It may be tactical (that is, it will endeavour to discover the posi- tions 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 reconnais- sance 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, infor- mation- 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 air- craft 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 effi- ciency 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
