CHAPTER 5
INTELLIGENCE AND RECONNAISSANCE

GENERAL

  1. Information of the enemy and of the terrain over which operations are to be conducted must be evaluated to determine its probable accuracy, and, together with other items of information, it must be interpreted to determine its probable significance. It then becomes military intelligence.

  2. From adequate and timely military intelligence the commander is able to draw logical conclusions concerning enemy lines of action. Military intelligence is thus an essential factor in the estimate of the situation and in the conduct of subsequent operations.

  3. Military intelligence functions and procedure are covered in detail in FM 30 series.

    INFORMATION COLLECTING AGENCIES

  4. The intelligence available initially concerning the enemy and the theater of operations is obtained from intelligence studies made in time of peace by the War Department and furnished the field forces prior to operations. This is supplemented by more detailed information obtained in the field from study of recent maps and map substitutes, captured documents and equipment, hostile and neutral press and radio; from interrogation of inhabitants, repatriates, prisoners, and deserters; from reports of agents, air and ground reconnaissance and observation, troops in contact with the enemy, aircraft warning service and special information services of component units; and from radio direction finding and other sources.

  5. Air reconnaissance extends the zone covered by ground reconnaissance and obtains information which will enable ground units to give effective direction to their reconnaissance. Photographs of the areas reconnoitered are of great value to both air and ground reconnaissance agencies.

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    Under favorable conditions, aviation can furnish early information of the enemy's general dispositions and movements to a considerable depth in rear of his security forces. It cannot provide continuous or detailed information, and frequently its negative information is unreliable, since it is subject to definite limitations resulting from inclement weather, darkness, forested terrain, antiaircraft fire, the activities of hostile combat aviation, and passive measures of antiaircraft defense.

    Night visual and photographic reconnaissance by means of artificial illumination will detect heavy troop and vehicle movements. Reconnaissance flights made shortly after dawn and before dark offer a favorable opportunity for discovery of night movements.

  1. Ground reconnaissance elements, on the other hand, cannot obtain a complete picture of the enemy situation to any great depth in rear of the hostile screen. They need the cooperation of aviation in order to conserve their combat strength. They can maintain continuous contact, operate under weather conditions which preclude air reconnaissance, and can determine details of enemy activity, strength, composition, and combat value.

  2. Reconnaissance units of horse cavalry are of great value on reconnaissance missions because of their ability to execute detailed ground reconnaissance within an appropriate area.

  3. Mechanized reconnaissance units are of great value on distant reconnaissance missions, and for reconnoitering on an extensive front. (See FM 2-10, FM 2-15, and FM 17-10.)

  4. When cavalry divisions or adequate mechanized reconnaissance forces are not available, and the reconnaissance mission indicates the probability of serious combat or necessitates operations at a considerable distance from the main forces, a composite force consisting of available mechanized reconnaissance elements and either porté horse cavalry or motorized infantry may be desirable. Such a force may be reinforced by other arms.

  5. Close and intensive reconnaissance by infantry, artillery, and engineer units supplements the more distant reconnaissance.

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    Infantry reconnaissance assumes special importance when cavalry or mechanized reconnaissance units are lacking or weak. It is constant and intensive when the opposing forces are in contact and especially during combat.

    Small engineer groups should constitute a portion of ground reconnaissance units to obtain and report information concerning routes of communication and movement and demolitions and obstructions.

    ORGANIZATION OF RECONNAISSANCE

  1. The essential elements of information consist of that information of the enemy, of the terrain not under our control, of meteorological conditions in territory held by the enemy, or hydrographic conditions needed by a commander in a particular situation in order to make a sound decision, conduct a maneuver, and avoid being surprised. The essential elements of information constitute the basis for orders governing the search for information.

  2. In the combat zone the following items are usually included among the essential elements of information: what are the strength, composition and dispositions of the enemy; what lines of action, which can interfere with our mission, are within the physical capabilities of the enemy; when and under what circumstances can he put each into effect; and whether, when, and in what strength he can be reinforced. The essential elements also include unknown details of terrain which may affect our own maneuver. They may also include items of information desired by higher, lower, or neighboring units, and data as to suitable distant objectives for air or mechanized units and on meteorological conditions at or en route to such objectives.

  3. Ordinarily, the military intelligence required by the essential elements of information relating to the enemy are deduced from numerous items of information which serve as indications of enemy action. Reconnaissance agencies are directed to search primarily for these indications. According to circumstances, some or all of the following items of information will furnish indications of value: whether there are any enemy forces in a specified area at a particular time; the identification of the enemy's leading elements and the contour of his front line; the frontage and depth of his dispositions;

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    his assembly positions; the location, size, and movement of his main forces or reserves; the location of his artillery; his measures for antiaircraft defense; the movement of supplies into or out of an area; the density of railroad traffic; entraining, detraining, entrucking, or detrucking; progress of construction and demolition; use of chemicals by the enemy; the location of his airdromes and landing fields, detraining stations, and principle supply and evacuation establishments; location and movements of enemy motorized and mechanized forces.

  1. The nearer the approach to the enemy, the more intensive is the reconnaissance. The most detailed information will be required concerning areas of importance in the contemplated maneuver. Detailed information of the terrain in the possible areas of combat is essential.

  2. Effective reconnaissance requires concentration of the available means on missions of importance. Depending on the situation, some reconnaissance elements may be held in reserve to reinforce the reconnaissance which is in progress, or to project reconnaissance in a new direction.

  3. The commander is responsible for all intelligence activities of his unit. He coordinates the activities of the reconnaissance agencies, avoiding duplication of effort by the assignment of missions and objectives and by informing each reconnaissance detachment of reconnaissances to be executed by others. He makes the necessary requests for information to higher and neighboring units.

    The commander establishes zones of responsibility for air reconnaissance by designating air boundaries between his own aviation and that of the next subordinate units. Air reconnaissance must extend to such distances as to assure against surprise by hostile ground forces.

    Orders for reconnaissance or observation should state definitely the information desired, where it is to be sought, and the destination and time of reports.

  4. Missions to aviation for the observation of specific roads, railroad centers, and exits of towns and woods must be stated in orders. These objectives are closely observed both day and night to discover the enemy's main forces and reinforcements, and their direction of movement.

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  1. During combat, observation aviation reconnoiters and observes, in accordance with reconnaissance orders, within the reconnaissance zone of the unit to which it is assigned or attached; observes and adjusts fire for the Field Artillery; supports front line units by observing and reporting enemy assemblies which constitute an immediate threat, by locating opposing front lines, and by maintaining contact between units; and performs such missions within its capabilities as may be specially ordered by the commander. Reconnaissance aviation carries out long-range reconnaissance.

  2. Ground reconnaissance elements gain and maintain contact with the enemy, and, by working through gaps and around the flanks and rear, endeavor to ascertain the strength, movements, composition, and dispositions of the enemy's main force, and the approach of enemy reinforcements.

  3. Orders for the development of a command frequently assign zones of reconnaissance to subordinate units. Each unit is habitually responsible for reconnaissance with its zone of advance or action. Flank units are also responsible for reconnaissance on their open flanks.

  4. While orders for intelligence activities issued by a large unit may be included in an intelligence annex to a field order, it will usually be necessary to issue part or all of them in fragmentary form.

    EXECUTION OF RECONNAISSANCE

  5. Reconnaissance is so executed that contact must be gained at the earliest practicable moment, and once gained must never be lost. The search for information must be unremitting. Reconnaissance is a responsibility of all units and is habitually directed to the front and to any open flank. As the situation requires, it is also directed to the rear.

  6. Ground forces assigned to reconnaissance missions secure information chiefly through the use of patrols. When, on account of hostile activities or the distance of objectives, patrols require close support in the execution of their mission, reconnaissance is executed by detachments which closely back up the action of patrols and furnish reliefs for patrol duty.

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  1. Terrain features that afford observation of the hostile dispositions constitute especial objectives of reconnaissance. Active and aggressive action of patrols in seizing such terrain features is indicated.

  2. Weak reconnaissance elements seek to avoid combat unless it is necessary for gaining essential information. If the enemy is superior, the reconnaissance mission is often more easily accomplished by containing the enemy's reconnaissance or security forces in front while pushing reconnaissance around their flanks.

  3. Essential information can frequently be obtained only through attack. Reconnaissance units attack when their mission requires it.

  4. When hostile resistance is encountered which cannot be brushed aside or enveloped, a reconnaissance in force constitutes the best means of clearing up an uncertain situation. Troops engaged in a reconnaissance in force usually make a local attack with a limited objective. The commander who orders a reconnaissance in force must consider the possibility that his intentions or those of the higher commander may thereby be disclosed. He must also be prepared for the possibility that such reconnaissance may bring on a general engagement.

  5. Arrangements as to details of cooperation and direct signal communication between air and ground agencies must be made for each phase of operations. The commander of the aviation unit must be informed of the routes of advance of any ground units with which he must communicate, and the locations of command posts, advance message centers, intermediate dropping grounds, and temporary landing fields.

  6. Under the protection of the leading elements, the commander usually makes a personal reconnaissance for information of the terrain.

    Reconnaissance parties are sent forward to determine the routes and covered areas available for the development of the command, the terrain, obstacles and barriers for antimechanized defense, gassed areas, defiles requiring antiaircraft protection, the location of position areas for the artillery and of covered assembly areas for infantry, cavalry and armored units, and the general location of the zone of resistance for

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    the organization of the defense or of a covering position to cover the development of the command.

  1. Without orders from the higher commander, each unit executes the reconnaissance necessary to its own operations within its own zone of action and toward any unsupported flanks. The methods of reconnaissance employed by the several arms are described in their respective field manuals.

    TRANSMISSION OF INFORMATION

  2. All subordinates of a command are responsible that their immediate commander is promptly and fully informed of the situation.

  3. While a commander who is in need of information from other headquarters is responsible for requesting it, neighboring units should habitually exchange pertinent information regardless of whether such a request has been made.

  4. Items of information that appear unimportant to a collecting agency should be reported as they may be of significant importance to a higher commander when considered in conjunction with other information. Negative information is frequently important; likewise, confirmation that the situation during a specific period of time has remained unchanged. First contact with the enemy, and new identifications, are always reported by the most rapid means available. Other reports of reconnaissance are made as required in orders.

  5. Front line troops are frequently so closely engaged in combat that they are unable to report as often as desired by the higher commander. Commanders make provision for obtaining prompt information by special reconnaissance and by sending liaison agents to higher, subordinate, and adjacent units. These provisions do not relieve subordinate commanders from making every effort to keep their superiors fully informed of the situation.

  6. The best information will be of no use if it arrives too late at the headquarters for which it is intended.

  7. Important and urgent information, in addition to being transmitted to the next higher commander, is sent

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    by the most rapid means available to all headquarters affected, without regard to the usual military channels.

    Artillery observers and liaison officers are often in a position to transmit to the higher commander over their own signal communication systems early reports of important combat events when such information might otherwise be delayed in transmission.

  1. The commander regulates signal communication to insure the prompt and reliable transmission of the results of reconnaissance. To facilitate the transmission of information between headquarters or units, he may establish advance message centers near the ground reconnaissance elements.

  2. During pauses in combat, or whenever the situation demands, subordinate commanders make brief intelligence reports to the next higher headquarters. Periodic reports are made as ordered by the higher commander.

  3. As required by the situation, military intelligence is disseminated to subordinate units in field orders, messages, or copies of periodic or special intelligence reports. The means of dissemination must be appropriate to the time available.

  4. For details regarding military intelligence methods and forms, see FM 30- series, and FM 101-5.

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