CHAPTER 4
SECURITY MISSIONS

  1. GENERAL.--Security missions which may be assigned to a rifle company include the following:

    1. Support of an advance guard.

    2. Support of a rear guard.

    3. Advance or rear guard.

    4. Flank guard.

    5. Support of an outpost for a bivouac.

    6. Part of a general outpost in defensive operations.

    7. Combat outpost of a front-line battalion in defensive operations.

    8. March outpost.

    A company having a security mission is issued its extra ammunition before beginning the mission, and its weapon carriers usually go with the company except as indicated in paragraph 92c.

  2. SUPPORT OF ADVANCE GUARD.--

    1. When a battalion constitutes the advance guard, the leading rifle company will ordinarily be designated as the support. (See FM 100-5.) The mission of the support is to reconnoiter to the front and to provide security for the element following in its immediate rear.

    2. Upon receipt of the advance guard order, the support commander prepares and issues his own order to his assembled subordinate leaders. The support commander's order usually contains--

      1. Information of the enemy and own troops.

      2. Organization of the support.

      3. Route and destination.

      4. Hour march begins.

      5. The distance at which the support is to follow the advance party.

      6. Special security and reconnaissance measures, including conduct at halts and responsibility for patrolling to the flanks.

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      1. Conduct of the advance.

      2. Position of the support commander.

      1. The support marches ahead of the reserve in three groups from rear to front as follows: the support proper; the advance party; the point. (See fig. 13.) The support company sends forward an advance party which should seldom exceed a platoon in strength. The advance party, in turn,


Figure 13
Initial advance guard formation.

        sends forward a point, usually a squad or half-squad. (See fig. 14.) Distances between elements of the support vary in accordance with the situation, the terrain, and conditions of visibility. These distances are sufficient to allow each succeeding element to deploy without serious interference from the enemy. However, the distances are not so great as to prevent each succeeding element from supporting the

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        element in front before the latter is destroyed. The following table shows average figures for road spaces and the average distances between elements for a support consisting of a rifle company for a march in daylight. This table is a guide only. At night, distances are considerably less than indicated in the table.

Element Strength Formation Road space in yards (average) Distance to next succeeding element in yards (average)

Point Squad Staggered 35 200
Advance party Platoon (less one squad). Column of twos (extended). 50 400
Support proper Rifle company (less one platoon). Column of twos 100 600

      1. The company weapon carriers will usually be under battalion control when contact is not imminent. When contact becomes imminent, they should be released to the company.

    1. Contact between the support and the advance party is maintained by connecting files sent forward by the support.

    2. The advance party is able to patrol, in broken country, to a distance of 200 to 300 yards to each flank of the route of march. Patrols to greater distances are provided by higher echelons. Foot patrols should seldom be sent to distances greater than 800 yards from the route of march. (See fig. 13.)

    3. The support commander ordinarily marches at the head of the support proper; however, he is free to go wherever his presence is required. He informs the advance guard commander, by the fastest means available, of any new information of the enemy or change in the situation.

    4. Upon encountering the enemy, the support commander promptly joins the advance party commander and, where the situation warrants, commits the support without detailed reconnaissance. The attack is launched at once in order to drive off the enemy or envelop his position. It is characterized

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      by rapidity of decision and action. If unable to drive off the enemy the support attempts to immobilize him by fire and sends out patrols to locate his flanks.

    1. If the enemy withdraws or is destroyed before the reserve of the advance guard is committed, the support promptly resumes its advance, in a suitable formation.


Figure 14
Disposition of point and advance party.

    1. During halts the support habitually establishes a march outpost. (See par. 99.) Each element also promptly posts observers at vantage points to the front and flanks to insure that hostile forces cannot approach undetected. The support commander coordinates the locations and sectors of surveillance of observers. The support will occupy terrain suitable for the execution of its protective mission.

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  1. SUPPORT OF REAR GUARD.--

    1. General.--Rear guards are provided for the protection of a foot or motorized column, which is marching away from the enemy, and for the protection of the rear of a column advancing toward the enemy if attack or harrassing action is possible. Whenever


Figure 15
Action of support of advance guard.

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      a rear guard is protecting motorized elements it is also motorized.

    1. Retrograde movement.--

      1. In a rear guard protecting a withdrawing force, the rear company usually is designated as the support. Its mission is to protect the rear guard element provided for the protection of a foot or motorized column which immediately precedes it in the direction of march.

      2. At a considerable distance from hostile forces a company having the mission of support of a rear guard adopts a formation similar to that of the support of an advance guard in reverse order of march. It is subdivided into three groups--the support, the rear party, and the rear point. The company usually details one rifle platoon to act as rear party which, in turn, details either a rifle squad or half-squad to act as rear point. The distances between elements of the support vary in accordance with the situation, the terrain, and visibility conditions, and correspond generally with the distances between similar elements of the advance guard. Except when enemy pursuit is close, each element of the rear guard follows the preceding element at a prescribed distance.

      3. When enemy pursuit is close, elements of the support effect such delay of the enemy advance as may be necessary to enable the next preceding unit to make suitable dispositions. Fire is opened at long range. Usually elements do not move toward the enemy to reinforce a subordinate element. The larger element occupies a delaying position to cover the withdrawal of the subordinate element which has become engaged. The element in contact with the enemy then withdraws under the protective fires of the element occupying the delaying position. The rate of retirement is coordinated with the main body and adjacent rear guard elements. In general, the combat action of a company operating as support of a rear guard in close contact with the enemy is conducted in accordance with the procedure described for delaying action in paragraph 89.

    2. In an advance.--When the transportation of the main body is moving at the tail of the main body, the rear guard for the advancing column is motorized and moves by bounds behind it. While moving, the support adopts the same relative formation as if on foot, except that distances between

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      elements are measured in time rather than in yards. The average time distances are: rear point to rear party--two minutes; rear party to support--four minutes. These time distances are subject to the same general variations as are indicated above for yardage distances for foot elements. When the transportation of the main body halts at the termination of a bound, the rear support halts, dismounts, and forms a march outpost.

  1. COMPANY AS ADVANCE OR REAR GUARD.--When the rifle company operates as an advance or rear guard of a small force, the reserve is omitted. The company disposes its elements and conducts its actions as does a rifle company acting as the support of a larger advance or rear guard. It may have supporting weapons attached.

  2. FLANK GUARD.--

    1. General.--

      1. A rifle company may be detailed to protect the flank of a marching column. When so detailed the company commander is given definite instructions as to what he is to do, and when and for how long it is to be done. When practicable, this company should be reinforced with antitank weapons, with portable radiotelephones, and with a sufficient number of motors to facilitate rapid communication with the unit detailing the flank guard. Such a security force may be dismounted or motorized. Since roads are the most dangerous avenues of approach for the initial attack by a hostile force, the company commander attempts to block these primarily; other avenues of approach also are covered.

      2. In case of attack, the main body commander is immediately notified and the flank guard delays the advance of the enemy until the main body can prepare for action or until the tail of the column passes a designated point. For other details, see FM 7-5, 7-20, 7-40, and 100-5.

    2. Occupying simultaneously a series of flank positions.--

      1. The company generally will occupy these positions in advance of the march of the main body. Preferably the company should be motorized to enable it to form a number of motorized detachments, each blocking an avenue of approach. A strong supporting element should be retained in a central location so that any detachment can be reinforced.

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        As the tail of the main body approaches a point on the route from which elements on the second position provide adequate flank protection, the first detachment should be moved rapidly to a previously reconnoitered location to the front. (See fig. 16.) This procedure is continued; the detachments remain in position until the main body has passed a point approximately opposite their positions, after which they move to designated positions ahead of and to the flank of the leading elements of the marching column.


Figure 16
Schematic diagram showing employment of flank guard occupying simultaneously a series of flank positions.

Notes.

  1. Detachment No. 1 moves to position No. 4 when tail of main body reaches A.

  2. Detachment No. 2 moves to position No. 5 (not shown) when tail of main body reaches B.

  3. Detachment No. 3 moves to position No. 6 (not shown) when tail of main body reaches C.

  4. Support at X remains near center detachment location; with an inadequate road net, support at X (Y) may be omitted and detachments are correspondingly reinforced in strength and number.

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      1. In occupying simultaneously a series of flank positions, road blocks are established. Demolitions may be accomplished, and small detachments are posted to cover them with fire. Rifle antitank grenades or antitank guns (if attached) are used to attack hostile armored vehicles.

      2. When the company is operating on foot it may be reassembled after the tail of the main body has passed a prescribed location or at a specified time. The company rejoins the main body at the earliest practicable time.

    1. Occupying a single flank position.--If there is only a single avenue of approach from a threatened flank, the company commander is directed to move to a single key position, the possession of which will afford the necessary protection to the main body. This key terrain feature may be defended until the mission is accomplished, or utilized as an initial delaying position.

    2. Moving on a parallel route.--If moving on a parallel route, the company commander provides for local security of the company by employing an advance and a rear guard, and by extensive use of flank patrols. Contact with the main body is maintained by patrols sent to points of observation, and by motor messenger, or radiotelephone, if available.

  1. SUPPORT OF OUTPOST FOR BIOUAC.--

    1. General.--

      1. A rifle company detailed as a support of an outpost for a bivouac is assigned an area on the outpost line of resistance and a sector of surveillance. The mission of the outpost is to provide time for the main force to prepare for combat. Fire is opened at long range and the enemy is held under constant fire as he approaches the position. The support is prepared for close combat. When the support has been assigned a delaying mission, it withdraws along previously reconnoitered routes to an intermediate delaying position or as may be directed by the outpost commander.

      2. Support areas on the outpost line of resistance are numbered from right to left. Heavy machine guns and other supporting weapons may be attached to the company. The company adopts a suitable formation to protect its movement to the outpost position and provide for its own security. For other details see FM 7-5, 7-20, 7-40, and 100-5.

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    1. Preliminary orders.--Upon receipt of orders, the company commander makes a map reconnaissance, informs his second-in-command as to his tentative plan, and issues specific instructions as to where the company is to be moved.

    2. Reconnaissance.--

      1. If practicable, the company commander precedes his unit to its assigned area and makes a detailed reconnaissance. Frequently enemy interference, or the threat thereof, will require him to make his reconnaissance under the protection of the march outpost.

      2. He confers with the march outpost commander as to the situation and the terrain. As soon as contact can be made, he also confers with commanders of adjacent supports. During his reconnaissance, the company commander determines locations and missions for each platoon and for any attached supporting units.

    3. Orders.--The company commander then decides upon his plan of organization and issues his orders to the platoon leaders. Frequently the orders are issued by message in fragmentary form.

    4. Organization of ground.--The selected position should provide observation for long-range machine-gun and mortar fires and permit the organization of close defensive fires. The company organizes the position as for a defense on a wide front (delay on one position.) (See par. 90.) The unoccupied intervals of the area are covered by fire and, wherever practicable, by obstacles. Attached heavy machine guns are employed for long-range direct fire covering the approaches to the position. They are assigned supplementary positions for reinforcing the flanking fires of the light machine guns. Attached 81-mm mortars are located to cover defiladed approaches to the position. They are also assigned close support missions. Attached antitank weapons are sited to cover the most probable routes of tank approach. Immediately upon arriving on the outpost position the troops construct slit trenches or foxholes, clear fields of fire, and develop camouflage in a manner similar to the organization of a defense area on a battle position.

    5. Conduct.--The company promptly covers its front with outguards and patrols. (See fig. 17.) Outguards, not exceeding the strength of one squad, occupy day positions (usually

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      within 400 yards of the outpost line of resistance) affording the most extensive views over the foreground. Outguards are numbered from right to left in each support area. At night outguards are posted so as to cover the most probable routes of hostile advance. Patrolling is greatly increased at night. Unless given specific missions, the patrols detailed from the support cover only their front and gaps between outguards. The support may be required to execute distant patrolling to the front and flanks, utilizing motors provided for this purpose. Stronger outguards (detached posts) are detailed to hold more distant features such as stream crossings, villages,


Figure 17
Schematic diagram showing dispositions of the outpost for a bivouac.

      and important road junctions. Communication with adjacent supports, between platoon defense areas, and between outguards is maintained by visiting patrols or by telephones. Patrols should go over their route during daylight.

  1. SUPPORT OF A BATTALION ON GENERAL OUTPOST.--

    1. The general outpost is divided into battalion areas. The battalion in turn subdivides its position into company areas. A rifle company occupying an area on the outpost line of resistance organizes its position and may be directed to conduct its action as for delaying action. (See pars. 89 and 90.)

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    1. The outpost order may prescribe that the outpost line of resistance be held a definite time or until other orders are received. In such case, the outpost organizes the position for protracted defense.

    2. In the organization of ground, deception is stressed. Dummy emplacements simulating the organization of a battle position are constructed to deceive the enemy and disperse his fire. The company covers its front with observation groups (outguards) and patrols as for the support of an outpost for a bivouac. (See par. 96f.)

  1. COMBAT OUTPOST OF FRONT-LINE BATTALION.--

    1. A battalion occupying an area on the main line of resistance provides for its local security by posting a combat outpost. The reserve company, or elements thereof, may be assigned this mission. If a general outpost is in position, the combat outpost ordinarily consists of a series of observation groups placed to observe the approaches to the position. When the proximity of the enemy does not permit the establishment of a general outpost, or the contemplated withdrawal of the general outpost will uncover the battalion front, the combat outpost may be stronger. If the terrain affords good fields of fire and covered routes of withdrawal, battalion supporting weapons are attached to the combat outpost. The combat outpost line is designated by the battalion commander.

    2. The combat outpost is organized as a series of outguards varying in strength from a half-squad to a rifle platoon. These outguards organize defense areas on positions affording observation and long fields of fire, and provide close rifle protection to supporting weapons. A support echelon may not be required, as the combat outpost ordinarily effects an early withdrawal. Since the distance from the battle position is short, there usually will be no intermediate delaying positions and the withdrawal will be made directly to the company assembly area. Outguards should be located within visual communicating distance of each other. If the terrain prevents this, contact is maintained by patrols and by telephones if they are available for this purpose. Patrolling between outguards is carried on during all periods of reduced visibility. Communication with the battalion command post is maintained by wire, radio, and messenger.

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    1. The combat outpost locates forward observers and sends patrols to the front and flanks for its own security. Fire is opened at long range and the combat outpost withdraws before the enemy reaches the area of close combat. The battalion commander is informed of the first approach of hostile forces, is kept advised of the hostile situation, and is notified when the combat outpost is forced to withdraw. The withdrawal is made along previously designated and reconnoitered routes. Front-line units through whose area the withdrawal is made are informed when the combat outpost has cleared their front. The battalion commander is notified when the combat outpost is assembled in the battalion area. When combat is interrupted by nightfall, battalions in contact immediately push forward combat outposts. In this case, the combat outpost sends forward patrols to gain and maintain contact with the enemy.

  1. MARCH OUTPOST.--The march outpost is the outpost established habitually by a marching unit making any temporary halt. It is established by advance, flank, and rear guards, and is generally formed by occupying critical terrain features controlling the approaches to the resting column, with special attention to the flanks. The strength of a march output may vary from a single rifle squad to a rifle company, reinforced with attached supporting weapons. Its size depends upon the size of the main body, duration of the temporary halt, nearness of the enemy and likelihood of early contact, and the nature of the terrain. When detailed as a march outpost, the rifle company receives specific instructions from the battalion commander. It then operates generally according to the methods prescribed for the support of an outpost for a bivouac. (See pars. 96 and 157h.)

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