Infantry Drills

FM 3-21.8 – Appendix F – Obstacle Reduction and Employment

Appendix F

Obstacle Reduction and Employment

The Army defines mobility operations as “those activities that enable a force to move personnel and equipment on the battlefield without delays due to terrain or obstacles.” Infantry units must be able to mass forces quickly at a chosen place and time to accomplish their assigned mission. Mobility is critical to achieving this situation. Mobility operations require the maintenance of force movement activities over great distances for extended periods of time. The Infantry platoon must be proficient in the reduction of obstacles to enable the movement of combat power through any obstacles while continuing to the objective.

Countermobility operations involve the augmentation of existing obstacles through the use of reinforcing obstacles that are integrated with direct- or indirect-fire systems. When employed effectively, this type of operation will disrupt, fix, turn, or block the enemy’s ability to maneuver while giving the Infantry platoon opportunities to exploit enemy vulnerabilities. To be effective in countermobility operations, the Infantry platoon must be proficient in the employment of obstacles.

 

Section I — Obstacle types and categories

F-1.       An obstacle is any obstruction that is designed or employed by friendly or enemy forces to disrupt, fix, turn, or block the movement of the opposing force. Obstacles can impose additional losses in personnel, time, and equipment. It is therefore vital that Infantry leaders and Soldiers be knowledgeable in the various types of obstacles; not only to employ them effectively, but to reduce them when employed by enemy forces.

F-2.       This appendix provides information on the types of obstacles (Section I), reduction of enemy obstacles (Section II), and employment of friendly obstacles (Section III). See FM 90-7, Combined Arms Obstacle Integration, for complete information on obstacles, and FM 20-32, Mine/Countermine Operations,  for complete information on mine and countermine operations.

F-3.       U.S. forces’ employment of certain obstacles, booby traps, and antihandling devices are governed by the Law of Land Warfare and any applicable international laws. Rules governing their employment are also listed in the appropriate sections in this appendix.

F-4.       There are four general types of obstacles. Each type is determined by its distinct battlefield purpose and the overall concept of the operation.

(1)           Protective obstacles are employed to protect Soldiers, equipment, supplies, and facilities from
enemy attacks or other threats.

(2)           Tactical obstacles directly affect the opponent’s maneuver in a way that gives the defending
force a positional advantage.

(3)           Nuisance obstacles impose caution on opposing forces. They disrupt, delay, and sometimes
waken or destroy follow-on echelons.

(4)           Phony obstacles deceive the attacking force concerning the exact location of real obstacles. They cause the attacker to question his decision to breach and may cause him to expend his reduction assets wastefully. Phony minefields are used to degrade enemy mobility and preservefriendly mobility. Intended to simulate live minefields and deceive the enemy, they are used when lack of time, personnel, or material prevents use of actual mines. They may also be used as gaps in live minefields. To be effective, a phony minefield must look like a live minefield, so Soldiers must bury metallic objects or make the ground look as though objects are buried.

F-5.       Obstacles are employed by both friendly and enemy forces. The two main categories of obstacles are:

(1)           Existing obstacles.

(2)           Reinforcing obstacles.

Existing Obstacles

F-6.       Existing obstacles are those natural or cultural restrictions to movement that are part of the terrain. Existing obstacles can be reinforced into more effective obstacles. They are normally in defilade from enemy observation (located where observation and fires can prevent the opposing force from breaching them), and are difficult to bypass. Existing obstacles include steep slopes, escarpments, ravines, rivers, swamps, deep snow, trees, and built-up areas.

Reinforcing Obstacles

F-7.       Reinforcing obstacles are used by both friendly and enemy forces to tie together, anchor, strengthen, and extend existing obstacles. Careful evaluation of the terrain to determine its existing obstructing or canalizing effect is required to achieve maximum use of reinforcing obstacles. Installation time and manpower are usually the two most important factors. The four types of reinforcing obstacles are:

(1)           Land mines.

(2)           Constructed obstacles.

(3)           Demolition obstacles.

(4)           Improvised obstacles.

Land Mines

F-8.     Land mines are explosive devices that are emplaced to kill, destroy, or incapacitate personnel/ equipment, and to demoralize an opposing force. A mine (or other explosive device) is detonated by the action of its target, the passage of time, or other controlled means (Figure F-1). There are two types of land-based mines: antitank (AT); and antipersonnel (AP). They can be employed in quantity to reinforce an existing obstacle within a specified area to form a minefield, or they can be used individually to reinforce nonexplosive obstacles such as wire. FM 20-32 is the primary reference for mine and countermine operations. See Section II for more information on reducing mine obstacles and Section III for more information on employing them.

Figure F-1. Methods of actuating explosives.

Constructed Obstacles

F-9.       Units create constructed obstacles with manpower or equipment without the use of explosives.
FM 5-34 covers constructed obstacles in detail. Examples of constructed obstacles include:

– Ditches. Ditches across roads and trails are effective obstacles. Large ditches in open areas require engineer equipment.

– Log Hurdles. Log hurdles act as “speed bumps” on roads.. They are easily installed and are most effective when used in conjunction with other obstacles.

– Log Cribs. A log crib is constructed of logs, dirt, and rocks. The logs are used to make rectangular or triangular cribs that are filled with dirt and rock. These are used to block narrow roads and defiles. Unless substantially built, log cribs will not stop tanks.

– Log Posts. Log posts embedded in the road and employed in depth can effectively stop tracked vehicles. If they are not high enough to be pushed out of the way, posts can cause a tracked vehicle to throw a track if it tries to climb over. If employed with wire and mines, they can also slow Infantry.

– Wire Entanglements. Wire entanglements impede the movement of dismounted Infantry, and in some cases, tracked and wheeled vehicles. Triple standard concertina is a common wire obstacle. However, there are other types, such as double apron, tanglefoot, and general-purpose barbed-tape obstacles. Figures F-2A and F-2B illustrate examples of wire and log obstacles. The materials used in constructing wire entanglements are relatively lightweight (compared to other obstacles) and inexpensive, considering the protection they afford.

 

Figure F-2A. Constructed wire and log obstacles.

 

Figure F-2B. Constructed wire and log obstacles.

Demolition Obstacles

F-10.    Units create demolition obstacles by detonating explosives. FM 5-250, Explosives and Demolitions, covers demolitions in detail. There are many uses for demolitions, but some examples are road craters and abatis.

F-11.    Road craters are effective obstacles on roads or trails if the areas on the flanks of the crater are tied into steep slopes or mined areas. Road craters can compel the opposing force to use earthmoving equipment, blade tanks, or mechanical bridging assets.

F-12.    Abatis are only effective if large enough trees, telephone poles, or other similar objects are available to stop the opposing force. An abatis is an obstacle created by cutting down trees so their tops are crisscrossed and pointing toward the expected enemy direction. It is most effective for stopping vehicles in a forest or narrow movement routes. This obstacle may be reinforced with mines.

Improvised Obstacles

F-13.    Improvised obstacles are designed by Soldiers and leaders with imagination and ingenuity when using available material and other resources. An example of obstacles in urban terrain is shown in Figure F-3. Improvised obstacles include the following:

– Rubble. Rubble from selected masonry structures and buildings in a built-up area will limit movement through an area and provide fortified fighting positions.

– Battle Damage. Damaged vehicle hulks or other debris are used as roadblocks.

– Flooding. Flooded areas are created by opening floodgates or breaching levees.

 

Figure F-3. Urban obstacles.

Section II — OBSTACLE Reduction

F-14.    Suppress, obscure, secure, reduce, and assault (SOSRA) are the breaching fundamentals that must be applied to ensure success when breaching against a defending enemy. These obstacle reduction fundamentals will always apply, but they may vary based on the specific METT-TC situation.

Breaching Fundamentals

Suppress

F-15.    Suppression is a tactical task used to employ direct or indirect fires or an electronic attack on enemy personnel, weapons, or equipment to prevent or degrade enemy fires and observation of friendly forces. The purpose of suppression during breaching operations is to protect forces reducing and maneuvering through an obstacle. Effective suppression is a mission-critical task performed during any breaching operation. Successful suppression generally triggers the rest of the actions at the obstacle. Fire control measures ensure that all fires are synchronized with other actions at the obstacle. Although suppressing the enemy overwatching the obstacle is the mission of the support force, the breach force should provide additional suppression against an enemy that the support force cannot effectively suppress.

Obscure

F-16.    Obscuration must be employed to protect forces conducting obstacle reduction and the passage of assault forces. Obscuration hampers enemy observation and target acquisition by concealing friendly activities and movement. Obscuration smoke deployed on or near the enemy’s position minimizes its vision. Screening smoke employed between the reduction area and the enemy conceals movement and reduction activities. It also degrades enemy ground and aerial observations. Obscuration must be carefully planned to provide maximum degradation of enemy observation and fires, but it must not significantly degrade friendly fires and control.

Secure

F-17.    Friendly forces secure reduction areas to prevent the enemy from interfering with obstacle reduction and the passage of the assault force through lanes created during the reduction. Security must be effective against outposts and fighting positions near the obstacle and against overwatching units as necessary. The far side of the obstacle must be secured by fires or be occupied before attempting any effort to reduce the obstacle. The attacking unit’s higher headquarters is responsible for isolating the breach area by fixing adjacent units, attacking enemy reserves in depth, and providing counterfire support.

F-18.    Identifying the extent of the enemy’s defenses is critical before selecting the appropriate technique to secure the point of breach. If the enemy controls the point of breach and cannot be adequately suppressed, the force must secure the point of breach before it can reduce the obstacle.

F-19.    The breach force must be resourced with enough maneuver assets to provide local security against the forces that the support force cannot sufficiently engage. Elements within the breach force that secure the reduction area may also be used to suppress the enemy once reduction is complete. The breach force may also need to assault to the far side of the breach and provide local security so the assault element can seize its initial objective.

Reduce

F-20.    Reduction is the creation of lanes through or over an obstacle to allow an attacking force to pass. The number and width of lanes created varies with the enemy situation, the assault force’s size and composition, and the scheme of maneuver. The lanes must allow the assault force to rapidly pass through the obstacle. The breach force will reduce, proof (if required), mark, and report lane locations and the lane-marking method to higher command headquarters. Follow-on units will further reduce or clear the obstacle when required. Reduction cannot be accomplished until effective suppression and obscuration are in place, the obstacle has been identified, and the point of breach is secure.

Assault

F-21.    A breaching operation is not complete until—

– Friendly forces have assaulted to destroy the enemy on the far side of the obstacle as the enemy is capable of placing or observing direct and indirect fires on the reduction area.

– Battle handover with follow-on forces has occurred, unless no battle handover is planned.

Breaching Organization

F-22.    A commander or platoon leader organizes friendly forces to accomplish breaching fundamentals quickly and effectively. This requires him to organize support, breach, and assault forces with the necessary assets to accomplish their roles. For tactical obstacle breaches, platoons and squads are normally assigned as either one or part of the following forces (Table F-1).

Support Force

F-23.    The support force’s primary responsibility is to eliminate the enemy’s ability to place direct or indirect fire on friendly force and interfere with a breaching operation. It must—

– Isolate the reduction area with fires and establish a support-by-fire position to destroy, fix, or suppress the enemy. Depending on METT-TC, this may be the weapons squad or the entire platoon.

– Mass and control direct and indirect fires to suppress the enemy and to neutralize any weapons that are able to bring fires on the breach force.

– Control obscuring smoke to prevent enemy-observed direct and indirect fires.

Breach Force

F-24.    The breach force assists in the passage of the assault force by creating, proofing (if necessary), and marking lanes. The breach force may be a combined-arms force. It may include engineers, reduction assets, and enough maneuver forces to provide additional suppression and local security. The entire Infantry platoon may be part of the breach force. The breach force may apply portions of the following breaching fundamentals as it reduces an obstacle.

Suppress

F-25.    The breach force must be allocated enough maneuver forces to provide additional suppression against various threats, including—

– Enemy direct-fire systems that cannot be effectively observed and suppressed by the support force due to the terrain or the masking of the support force’s fires by the breach force as it moves forward to reduce the obstacle.

– Counterattacking and or repositioning forces that cannot be engaged by the support force.

Obscure

F-26.    The breach force employs smoke pots, if necessary, for self-defense and to cover lanes while the assault force is passing.

Secure

F-27.    The breach force secures itself from threat forces that are providing close-in protection of the obstacle. The breach force also secures the lanes through the tactical obstacles once they are created to allow safe passage of the assault force.

Reduce

F-28.    The breach force performs its primary mission by reducing the obstacle. To support the development of a plan to reduce the obstacle, the composition of the obstacle system must be an information requirement. If the obstacles are formidable, the Infantry platoon will be augmented with engineers to conduct reduction. Without engineers and special equipment such as Bangalore torpedoes and line charges, mine fields must be probed.

Assault Force

F-29.    The breach force assaults through the point of breach to the far side of an obstacle and seizes the foothold. The assault force’s primary mission is to destroy the enemy and seize terrain on the far side of the obstacle to prevent the enemy from placing direct fires on the created lanes. The assault force may be tasked to assist the support force with suppression while the breach force reduces the obstacle.

F-30.    The assault force must be sufficient in size to seize the point of penetration. Combat power is allocated to the assault force to achieve a minimum 3:1 ratio on the point of penetration. The breach and assault assets may maneuver as a single force when conducting breaching operations as an independent company team conducting an attack.

F-31.    If the obstacle is defended by a small enemy force, assault and breach forces’ missions may be combined. This simplifies C2 and provides more immediate combat power for security and suppression.

F-32.    Fire control measures are essential because support and breach forces may be firing on the enemy when the assault force is committed. Suppression of overwatching enemy positions must continue and other enemy forces must remain fixed by fires until the enemy has been destroyed. The assault force must assume control for direct fires on the assault objective as support and breach force fires are ceased or shifted. Table F-1 illustrates the relationship between the breaching organization and breaching fundamentals.

Table F-1. Relationship between breaching organization and breaching fundamentals.

Breaching Organization

Breaching Fundamentals

Responsibilities

Support force Suppress

Obscure

Suppress enemy direct fire systems covering the reduction area.

Control obscuring smoke.

Prevent enemy forces from repositioning or counterattacking to place direct fires on the breach force.

Breach force Suppress (provides additional
suppression)

Obscure (provides additional obscuration in the reduction area)

Secure (provides local security)

Reduce

Create and mark the necessary lanes in an obstacle.

Secure the near side and far side of an obstacle.

Defeat forces that can place immediate direct fires on the reduction area.

Report the lane status/location.

Assault force Assault

Suppress (if necessary)

Destroy the enemy on the far side of an obstacle if the enemy is capable of placing direct fires on the reduction area.

Assist the support force with suppression if the enemy is not effectively suppressed.

Be prepared to breach follow-on and or protective obstacles after passing through the reduction area.

Detailed Reverse Planning

F-33.    The platoon leader must develop the breaching plan using the following sequence when planning for a protective obstacle breach. The platoon leader can plan to breach wire, mine fields, trenches, and craters (Figure F-4).

– Reverse planning begins with actions on the objective.

– Actions on the objective drive the size and composition of the assault force.

– The size of the assault force determines the number and location of lanes to be created.

– The ability of the enemy to interfere with the reduction of the obstacle determines the size and composition of the security element in the breach force.

– The ability of the enemy to mass fires on the point of breach determines the amount of suppression and the size and composition of the support force.

 

Figure F-4. Reverse planning.

F-34.    The approved technique for conducting obstacle breaching operations is suppress, obscure, secure, reduce, assault (SOSRA). The section focuses specifically on platoon reduction techniques of land mines, construction obstacles, urban obstacles, and booby traps and expedient devices.

F-35.    As part of reducing obstacles, units must also detect, report, proof, and mark.

F-36.    Detection is the actual confirmation of the location of obstacles. It may be accomplished through reconnaissance. It can also be unintentional (such as a vehicle running into a mine or wire). Detection is used in conjunction with intelligence-gathering operations, bypass reconnaissance, and breaching/clearing operations. Specific detection methods for mines and booby traps are discussed further in this section.

F-37.    Intelligence concerning enemy minefields is reported by the fastest means available. A SPOTREP should be sent to higher headquarters when the Infantry platoon or squad has detected a minefield or any other obstacle. This should be done whether they are sent on a specific minefield or obstacle reconnaissance mission, or if they encounter one in the course of normal operations. The SPOTREP should contain as much information as possible including the type, location, and size of the obstacle, and the results of any reduction efforts.

F-38.    Proofing is normally done by engineers by passing a mine roller or another mine-resistant vehicle through the minefield to verify that a lane is free of mines. If the risk of live mines remaining in the lane does not exceed the risk of loss to enemy fires while waiting, proofing may not be practical. Some mines are resistant to specific breaching techniques. For example, magnetically fused mines may be resistant to some explosive blasts. So proofing should be done when the time available, the threat, and the mission allow. Proofing also involves verifying that other obstacles (such as wire) are free of explosive or injurious devices.

F-39.    Marking breach lanes and bypasses is critical to obstacle reduction.

Reduce a Minefield

F-40.    Most types of obstacles do not cause casualties directly. Minefields do have this potential, and will cause direct casualties if not reduced effectively. Buried mines are usually found in a highly prepared defense. When training for the reduction of surface-laid and buried minefields, always assume the presence of antihandling devices (AHDs) and trip wires until proven otherwise.

Minefield Detection

F-41.    The three types of minefield detection methods the platoon might employ are visual, physical (probing), and electronic.

Visual Detection

F-42.    Visual detection is part of all combat operations. Soldiers should constantly be alert for minefields and all types of enemy obstacles. Soldiers visually inspect the terrain for the following obstacle indicators:

– Trip wires and wires leading away from the side of the road. They may be firing wires that are partially buried.

– Signs of road repair (such as new fill or paving, road patches, ditching, and culvert work).

– Signs placed on trees, posts, or stakes. Threat forces mark their minefields to protect their own forces.

– Dead animals or damaged vehicles.

– Disturbances in previous tire tracks or tracks that stop unexplainably.

– Odd features in the ground or patterns that are not present in nature. Plant growth may wilt or change color; rain may wash away some of the cover; the cover may sink or crack around the edges; or the material covering the mines may look like mounds of dirt.

– Civilians who may know where mines or booby traps are located in the residential area. Civilians staying away from certain places or out of certain buildings are good indications of the presence of mines or booby traps. Question civilians to determine the exact locations.

– Pieces of wood or other debris on a road. They may be indicative of pressure or pressure-release firing devices. These devices may be on the surface or partially buried.

– Patterns of objects that could be used as a sighting line. An enemy can use mines that are fired by command, so road shoulders and areas close to the objects should be searched.

– Berms may indicate the presence of an AT ditch.

Physical (Probing) Detection

F-43.    Physical detection (probing) is very time-consuming and is used primarily for mine-clearing operations, self-extraction, and covert breaching operations. Detection of mines by visual or electronic methods should be confirmed by probing. Detailed probing instructions can be referenced in FM 21-75.

Electronic Detection

F-44.    Electronic detection is effective for locating mines, but this method is time-consuming and exposes personnel to enemy fire. In addition, suspected mines must be confirmed by probing. As in probing, 20 to 30 minutes is the maximum amount of time an individual can use the detector effectively.

F-45.    The AN/PSS-12 mine detector (Figure F-5) is very effective at finding metallic mines, but is less effective against low-metal mines. Employment and operation procedures for the AN/PSS-12 are discussed in FM 20-32. Technical data is available in TM 5-6665-298-10, Operator’s Manual for Mine Detecting Set AN/PSS-12. The detector is handheld and identifies suspected mines by an audio signal in the headphones.

 

Figure F-5. AN/PSS-12 mine detector.

Minefield Reduction and Clearing Equipment

F-46.    Minefield reduction and clearing equipment is broken down into explosive, manual, mechanical, and electronic. While chiefly an engineer task, the platoon unit might need to reduce a minefield depending on the situation. The leader masses reduction assets to ensure it will successfully create as many lanes as necessary to ensure the rapid passage of the assault force through the obstacle system. If necessary, the leader must carefully plan and synchronize the creation of additional lanes to reduce the potential for fratricide with assaulting troops. The distance between lanes depends on the enemy, the terrain, the need to minimize the effects of enemy artillery, the direct-fire plan of the support force, C2, and the reduction-site congestion.

F-47.    The breach force should be organized and equipped to use several different reduction techniques in case the primary technique fails. Additional reduction assets should be present to handle the unexpected. Normally, 50 percent more reduction assets than required for obstacle reduction are positioned with the breach force. Mechanical and electronic reduction techniques and equipment are employed by engineers and can be found in FM 20-32.

Explosive Minefield Reduction

F-48.    FM 20-32 lists all explosive minefield reduction techniques and equipment. The different types of explosive minefield-reduction equipment that the platoon might use to breach obstacles are discussed below.

M1A1/M1A2 Bangalore Torpedo

F-49.    The Bangalore torpedo (Figure F-6) is a manually emplaced, explosive-filled pipe designed as a wire breaching device that is also effective against simple pressure-activated AP mines. It is issued as a demolition kit and consists of 10 1.5-meter tubes, 10 connecting sleeves, and 1 nose sleeve. Each tube contains 4 kilograms of HE and weighs 6 kilograms. The kit clears a 1-by 15-meter lane.

Figure F-6. Bangalore torpedo.

F-50.    All torpedo sections have a threaded cap well at each end so they can be assembled in any order. The connecting sleeves are used to connect the torpedo sections together. An individual or pair of Soldiers connect the number of sections needed, and then push the torpedo through the AP minefield before priming the torpedo. A detailed reconnaissance is conducted before using the Bangalore torpedo to ensure trip wires have not been used. The Bangalore torpedo generates one short impulse. It is not effective against pronged, double-impulse, or pressure-resistant AP/AT mines.

WARNING

Do not modify the Bangalore torpedo. Cutting the Bangalore in half or performing any other modification could cause the device to explode.

Antipersonnel Obstacle Breaching System

F-51.    The Antipersonnel Obstacle Breaching System (APOBS) (Figure F-7) is a man-portable device that is capable of quickly creating a footpath through AP mines and wire entanglements. It provides a lightweight, self-contained, two-man, portable line charge that is rocket-propelled over AP obstacles away from the obstacle’s edge  from a standoff position

F-52.    For dismounted operations, the APOBS is carried in 25-kilogram backpacks by no more than two Soldiers for a maximum of 2 kilometers. One backpack assembly consists of a rocket-motor launch mechanism containing a 25-meter line-charge segment and 60 attached grenades. The other backpack assembly contains a 20-meter line-charge segment and 48 attached grenades.

F-53.    The total weight of the APOBS is about 54 kilograms. It is capable of breaching a footpath about 0.6 by 45 meters and is fired from a 25-meter standoff.

Figure F-7. Antipersonnel obstacle breaching system (APOBS).

Manual Minefield Reduction

F-54.    Manual procedures are normally conducted by engineers (but can also be performed by Infantry units) and are effective against all obstacles under all conditions. Manual procedures involve dismounted Soldiers using simple explosives or other equipment to create a lane through an obstacle or to clear an obstacle. These procedures expose the Soldier and may be manpower and time-intensive. While mechanical and explosive reduction procedures are normally preferred, the Infantry platoon may have to use manual procedures for the following reasons:

– Explosive, mechanical, and electronic reduction assets are unavailable or ineffective against the type of obstacle.

– Terrain limitations.

– Stealth is required.

F-55.    Different manual reduction techniques for surface-laid and buried minefields are discussed below.

Surface-Laid Minefield

F-56.     First use grappling hooks from covered positions to check for trip wires in the lane. The limited range of the tossed hook requires the procedure to be repeated through the estimated depth of the obstacle. A demolition team then moves through the lane. The team places a line main down the center of the lane, ties the line from the explosive into the line main, and places blocks of explosive next to surface-laid mines. After the mines are detonated, the team makes a visual check to ensure that all mines were cleared before directing a proofing roller and other traffic through the lane. Members of the demolition team are assigned special tasks such as grappler, detonating-cord man, and demolitions man. All members should be cross-trained on all procedures. Demolitions are prepared for use before arriving at the point of breach (refer back to Table F-1). The platoon must rehearse reduction procedures until execution is flawless, quick, and technically safe. During reduction, the platoon will be exposed in the lane for five minutes or more depending on the mission, the minefield depth, and the Infantry platoon’s level of training.

Buried Minefield

F-57.     Manually reducing a buried minefield is extremely difficult to perform as part of a breaching operation. If mine burrows are not easily seen, mine detectors and probes must be used to locate mines. Mines are then destroyed by hand-emplaced charges. As an alternative, mines can be removed by using a grappling hook and, if necessary, a tripod (Figure F-8). Using a tripod provides vertical lift on a mine, making it easier to pull the mine out of the hole.

F-58.    The leader organizes Soldiers into teams with distinct, rehearsed missions including grappling, detecting, marking, probing, and emplacing demolitions and detonating cord. The platoon is exposed in the obstacle for long periods of time.

Figure F-8. Tripod.

Grappling Hook

F-59.    The grappling hook is a multipurpose tool used for manual obstacle reduction. Soldiers use it to detonate mines from a standoff position by activating trip wires and AHDs. After the grapnel is used to clear trip wires in a lane, dismounted Soldiers can move through the minefield, visually locate surface-laid mines, and prepare mines for demolition. In buried minefields, Soldiers grapple and then enter the minefield with mine detectors and probes.

F-60.    Multiple grapplers can clear a lane of trip wires quickly and thoroughly, but they must time their efforts and follow procedures simultaneously. A hit on a trip wire or a pressure fuse can destroy the grappling hook and the cord, so the platoon should carry extras.

F-61.    There are two types of grappling hooks: hand-thrown; and weapon-launched.

F-62.    Hand-Thrown. A 60+-meter light rope is attached to the grappling hook for hand throwing. The throwing range is usually no more than 25 meters. The excess rope is used for the standoff distance when the thrower begins grappling. The thrower tosses the grappling hook and seeks cover before the grappling hook and rope touch the ground in case their impact detonates a mine. He then moves backward, reaches the end of the excess rope, takes cover, and begins grappling. Once the grappling hook is recovered, the thrower moves forward to the original position, tosses the grapnel, and repeats the procedure at least twice. He then moves to the end of the grappled area and repeats this sequence through the depth of the minefield.

F-63.    Weapon-Launched. A 150-meter lightweight rope is attached to a lightweight grappling hook that is designed to be fired from an M16-series rifle using an M855 cartridge. The grappling hook is pushed onto the rifle muzzle with the opening of the retrieval-rope bag oriented toward the minefield. The firer is located 25 meters from the minefield’s leading edge and aims the rifle muzzle at a 30-to 40-degree angle for maximum range. Once fired, the grappling hook travels 75 to 100 meters from the firer’s position. After the weapon-launched grappling hook (WLGH) has been fired, the firer secures the rope, moves 60 meters from the minefield, moves into a prone position, and begins to grapple. The WLGH can be used only once to clear a minefield, but it can be reused up to 20 times for training because blanks are used to fire it.

Demolitions

F-64.     Different types of demolitions can be used for minefield obstacle reduction (Table F-2). FM 5-250 covers each different type of demolition available to support all Infantry missions. Demolitions are used differently against certain types of mines:

– Pressure-Fused AP Mine. Place at least a 1-pound charge within 15.2 centimeters of simple pressure-fused mines. Ensure that the charge is placed within 2.54 centimeters of blast-hardened mines.

– Trip-Wire/Break-Wire-Fused AP Mine. Place at least a 1-pound charge within 15.2 centimeters of the mine after the mine at the end of a trip wire has been located. Soldiers can use elevated charges if necessary against the Claymore and stake-type mines.

– Influence-Fused AP Mine. Do not use demolitions.

– Command-Detonated Blast Mine. Ensure that the observer is neutralized before approaching. Elevated charges can be used if necessary against Claymore mines.

Table F-2. Demolitions.

Item Description
M183 Satchel Charge Consists of 16 M112 (C4) charges and four priming assemblies. Total explosive weight of 20 pounds. Used primarily for breaching obstacles or demolishing structures when large charges are required. Also is effective on smaller obstacles such as small dragon’s teeth.
M112 Charge Consists of 1.25 pounds of C4 packed in an olive drab Mylar film container with a pressure-sensitive adhesive tape on one surface. Primarily used for cutting and breaching. Because of its ability to cut and be shaped, the M112 is ideally suited for cutting irregularly-shaped targets such as steel. The adhesive backing allows you to place the charge on any relatively flat surface.
Modernized Demolition Initiator (MDI) MDI is a new family of nonelectric blasting caps and associated items. Components simplify initiation systems and improve reliability and safety. Components include the M11 high strength blasting cap, the M12 and M13 low strength blasting caps, and the M14 high strength time delay cap.
Detonating Cord Consists of a core of HE (6.4 pounds of PETN per 1,000 feet) wrapped in a reinforced and waterproof olive drab coating. Can be used to prime and detonate single or multiple explosive charges simultaneously. Can be used in conjunction with the MDI components.

Marking and Crossing the Minefield

F-65.    Effective lane marking allows the leader to project the platoon through the obstacle quickly with combat power and C2. It also gives the Infantry platoon or squad confidence in the safety of the lane and helps prevent unnecessary minefield casualties.

F-66.    Once a footpath has been probed and the mines marked or reduced, a security team should cross the minefield to secure the far side. After the far side is secure, the rest of the unit should cross. If mines and any trip wires have been identified but not reduced, the mine and the line of the trip wire are marked along the ground surface, 12 inches before the trip wire (Figure F-9).

Figure F-9. Marking a footpath.

Reduce a Constructed Obstacle

F-67.    Reduction methods for enemy wire and tank ditch obstacles are as follows.

Reduce a Wire Obstacle

F-68.    The enemy uses wire and concertina obstacles to separate Infantry from tanks and to slow or stop the Infantry movement. His wire obstacles are similar to ours. On patrol, reducing a wire obstacle may require stealth and is conducted using wire cutters or by crawling under or crossing over the wire. It may not require stealth during an attack and can be accomplished with Bangalore torpedoes and wire cutters.

Cut the Wire

F-69.    To cut through a wire obstacle with stealth—

– Cut only the lower strands and leave the top strand in place. That makes it less likely that the enemy will discover the gap.

– Cut the wire near a picket. To reduce the noise of a cut, have another Soldier wrap cloth around the wire and hold the wire with both hands. Cut part of the way through the wire between the other Soldier’s hands and have him bend the wire back and forth until it breaks. If you are alone, wrap cloth around the wire near a picket, partially cut the wire, and then bend and break the wire.

F-70.    To reduce an obstacle made of concertina—

– Cut the wire and stake it back to keep the breach open.

– Stake the wire back far enough to allow room to crawl through or under the obstacle.

Bangalore Torpedo

F-71.    After the Bangalore torpedo has been assembled and pushed through the wire obstacle, prime it with either an electric or nonelectric firing system (Figure F-10). To prevent early detonation of the entire Bangalore torpedo if you hit a mine while pushing it through the obstacle, attach an improvised (wooden) torpedo section to its end. That section can be made out of any wooden pole or stick that is the size of a real torpedo section. Attach the nose sleeve to the end of the wooden section. Once the Bangalore torpedo has been fired, use wire cutters to cut away any wire not cut by the explosion.

Figure F-10. Reducing wire obstacles with bangalore torpedos.

Reduce an Urban Obstacle

F-72.    Understanding how to employ and incorporate reduction techniques is an important part of urban operations. Gaining quick access to targeted rooms is integral to room clearing. Reduction teams need to be supported by fires or obscurants. Reduction operations should be performed during hours of limited visibility whenever possible. Reduction techniques vary based on construction encountered and munitions available.

F-73.    The assault team’s order of march to the breach point is determined by the method of reduction and its intended actions at the entry point. This preparation must be completed prior to or in the last covered and concealed location before reaching the entry point. Establishing an order of march aids the team leader with C2 and minimizes exposure time in open areas and at the entry point. One order of march technique is to number the assault team members one through four. The number-one man should always be responsible for frontal and door security. If the reduction has been conducted prior to its arrival, the assault team quickly moves through the entry point. If a reduction has not been made prior to its arrival at the entry point, depending on the type of breach to be made, the team leader conducts the reduction himself or signals forward the breach man or element. One option is to designate the squad leader as the breach man. If the breach man is part of the assault team, he will normally be the last of the four men to enter the building or room. This allows him to transition from his reduction task to his combat role. See FM 3-06.11, Combined Arms Operations in Urban Terrain, for more information on movement and breaching methods.

F-74.    The three urban reduction methods discussed in this appendix are mechanical, ballistic, and explosive.

Breach Locations

F-75.    The success of the assault element often depends on the speed with which they gain access into the building. It is important that the breach location provide the assault element with covered or concealed access, fluid entry, and the ability to be overwatched by the support element.

Creating Mouseholes

F-76.    Mouseholes provide a safe means of moving between rooms and floors. C4 plastic explosive can be used to create mouseholes when lesser means of mechanical reduction fail. Because C4 comes packaged with an adhesive backing or can be emplaced using pressure-sensitive tape, it is ideal for this purpose. When using C4 to blow a mousehole in a lath and plaster wall, one block or a strip of blocks should be placed on the wall from neck-to-knee height. Charges should be primed with detonating cord or MDI to obtain simultaneous detonation that will blow a hole large enough for a man to fit through.

Expedient Reduction Methods

F-77.    Because the internal walls of most buildings function as partitions rather than load-bearing members, smaller explosive charges can be used to reduce them. When C4 or other military explosives are not available, one or more fragmentation grenades or a Claymore mine can be used to reduce some internal walls. These field-expedient reduction devices should be tamped to increase their effectiveness and to reduce the amount of explosive force directed to the rear. Take extreme care when attempting to perform this type of reduction because fragments may penetrate walls and cause friendly casualties. If walls are made of plaster or dry wall, mechanical reduction may be more effective.

Windows and Restrictive Entrances

F-78.    Regardless of the technique used to gain entry, if the breach location restricts fundamental movement into the room or building, local or immediate support must be used until the assault team can support itself. For example, as a Soldier moves through a window and into the room, he may not be in a position to engage an enemy. Therefore, another window that has access to the same room may be used to overwatch the lead team’s movement into the room. The overwatching element can come from the initial clearing team or from the team designated to enter the breach location second.

Mechanical Reduction

F-79.    This method requires increased physical exertion by one or more Soldiers using hand tools such as axes, saws, crowbars, hooligan’s tools, or sledgehammers to gain access. Although most Soldiers are familiar with these tools, practice on various techniques increases speed and effectiveness. The mechanical reduction is not the preferred primary breaching method because it may be time consuming and defeat the element of surprise. However, the ROE and situation may require the use of these tools, so Soldiers should be proficient in their use.

F-80.    Typically, the order of movement for a mechanical breach is the initial assault team, followed by the breach man or element. At the breach point, the assault team leader brings the breach team forward while the assault team provides local security. After the reduction is conducted, the breach team moves aside and provides local security as the assault team enters the breach. See FM 3-06.11 for additional information concerning mechanical reduction and breaching.

F-81.    When developing an urban operations mechanical breach kit SOP, Infantry units must consider their METL and the unit tactical SOP.

Ballistic Reduction

F-82.    Ballistic reduction requires the use of a weapon firing a projectile at the breach point. Ballistic reduction is not a positive means of gaining entry and should not be considered the primary method for gaining initial entry into a structure. It may not supply the surprise, speed, and violence of action necessary to minimize friendly losses on initial entry. In certain situations, it may become necessary to use ballistic reduction as a back-up entry method. A misfire of an explosive charge or the compromise of the assault element during its approach to the target may necessitate the use of ballistic reduction as a means of initial entry into the structure. Ballistic reduction may have to be followed up with a fragmentation, concussion, or stun grenade before entry.

F-83.    Once initial entry is gained, shotgun ballistic reduction may become the primary method for gaining access to subsequent rooms within the structure. Surprise is lost upon initial entry, and other reduction methods are often too slow, tending to slow the momentum of the assault team. If a door must be used for entry, several techniques can be used to open the door. Doors should be considered a fatal funnel because they are usually covered by fire, or may be booby-trapped. See FM 3-06.11 for more information concerning weapon employment and effects.

F-84.    Unless a deliberate breach is planned, the platoon can employ a series of progressive reductions. An example is an attempt to open a door by using the doorknob first, then shotgun reduction, then explosive reduction as a final option. Mechanical reduction can be used to clean up a failed attempt of a shotgun or explosive reduction, but can also be used as the primary reduction technique. Based on the multiple situations that the complex urban environment presents, the leader needs latitude in his options.

Exterior Walls

F-85.    For exterior walls, the use of a BFV or artillery piece in the direct fire role is ideal if the structure will support it and if the ROE will allow it. The BFV’s 25-mm cannon is an effective reduction weapon when using HE rounds and firing a spiral firing pattern (Figure F-11). The main gun of an M1A1/A2 tank is very effective when using the high explosive antitank (HEAT) round. However, the armor-piercing discarding-sabot (APDS) round rarely produces the desired effect because of its penetrating power.

 

Figure F-11. Spiral firing pattern.

Doors, Windows, and Interior Walls

F-86.    The 12-gauge shotgun breaching round is effective on doorknobs and hinges, while standard small arms (5.56 mm and 7.62 mm) have proven to be virtually ineffective for reducing obstacles. These should not be used except as a last resort because of their ricochet potential and shoot-through capability. Ballistic reduction of lightly-constructed interior walls by shotgun fire is normally an alternate means of gaining entry.

 

WARNING

The fragmentation and ricochet effects of standard small arms (5.56 mm and 7.62 mm) as breaching rounds is unpredictable and considered extremely dangerous. Do not attempt in training.

Rifle-Launched Entry Munitions

F-87.    Rifle-launched entry munitions (RLEM) allow a remote ballistic reduction of an exterior door or window without having the assault or breaching element physically present at the entry point. This allows the assault element to assume a posture for entry in the last covered and concealed position before the breach. The RLEM firer is not normally part of the assault element but rather a part of the breaching or support element. This allows the RLEM to be fired from one position while the assault element waits in another position. In the event that the first round does not affect the reduction, the firer should prepare a second round for the reduction or a second firer should be prepared to engage the target.

WARNING

The firer must be a minimum of 10 meters from the target to safely employ a 150-gram round.

 

NOTE:  Exact minimum safe distances for firers and assault elements have not been established for the 150-gram round.

Shotgun Reduction

F-88.    Various shotgun rounds can be used for ballistic reduction. Breaching and clearing teams need to be familiar with the advantages as well as the disadvantages of each type of round. Leaders must consider the potential for over penetration on walls and floors in multi-story buildings to avoid potential fratricide incidents or killing of noncombatants.

– Rifled Slugs. Rifled slugs defeat most doors encountered, including some heavy steel doors. However, rifled slugs present a serious over penetration problem and could easily kill or injure anyone inside the room being attacked. Rifled slugs are excellent antipersonnel rounds and can be used accurately up to 100 meters.

– Bird Shot. Bird shot (number 6 through number 9 shot) is used in close-range work up to 15 meters. A 2 ¾-inch shell of number 9 shot typically contains an ounce of shot (though it can be loaded to 1 ½-ounce with an accompanied increase in recoil). The major advantage of bird shot is it does not over penetrate. Therefore, bird shot poses little hazard to fellow team members in adjoining rooms. When used at close range, bird shot offers the same killing potential as buckshot, especially in a full choke shotgun intended for dense shot patterns. Another advantage of bird shot is low recoil. This feature allows for faster recovery and quicker multi-target engagements. A disadvantage with bird shot is rapid-energy bleed-off that reduces penetration at medium and long ranges. Moreover, the small size of the individual pellets requires hits be made with a majority of the shot charge to be effective. A hit with one-third of the number 9 shot charge may not be fatal, unless the shot is at extremely close range. These disadvantages are negated when birdshot is fired from a full choke shotgun where it will produce a pattern that is quite small inside of 10 meters. Inside 5 meters, all of the shot will be clumped like a massive single projectile.

– Buckshot. Buckshot is used in close- to medium-range work, up to 30 meters. Because of its larger size, buckshot is more lethal than bird shot. A 2 ¾-inch shell of 00 buckshot contains nine .30-caliber balls. One .30-caliber ball of the 00 buckshot charge hit can prove fatal. Buckshot also retains its energy longer. Therefore, it is lethal at longer ranges than bird shot. A disadvantage of buckshot is over penetration. Because buckshot is typically loaded with heavier shot charges, it also has very heavy recoil. This problem becomes apparent when numerous shots have been taken and can result in fatigue.

– Ferret Rounds. Ferret rounds contain a plastic slug filled with liquid chemical irritant (CS). When shot through a door or wall (drywall or plywood), the plastic slug breaks up and a fine mist of CS is sprayed into the room. The effectiveness of one round is determined by the size of the room on the other side of the door or the wall and also the ventilation in that room.

F-89.    When using the shotgun as an alternate reduction method to gain entry, shooters must consider the following target points on the door.

– Doorknob. Never target the doorknob itself because when the round impacts, the doorknob has a tendency to bend the locking mechanism into the doorframe. In most cases this causes the door to be bent in place and prevents entry into the room.

– Locking Mechanism. When attacking the locking mechanism, focus the attack on the area immediately between the doorknob and the doorframe. Place the muzzle of the shotgun no more than one inch away from the face of the door directly over the locking mechanism. The angle of attack should be 45 degrees downward and at a 45-degree angle into the doorframe. After breaching the door, kick it swiftly. This way, if the door is not completely open, a strong kick will usually open it. When kicking the door open, focus the force of the kick at the locking mechanism and close to the doorjamb. After the locking mechanism has been reduced, this area becomes the weakest part of the door.

– Hinges. The hinge breach technique is performed much the same as the doorknob reduction, except the gunner aims at the hinges. He fires three shots per hinge—the first at the middle, then at the top and bottom. He fires all shots from less than an inch away from the hinge. Because the hinges are often hidden from view, the hinge reduction is more difficult. Hinges are generally 8 to 10 inches from the top and bottom of the door. The center hinge is generally 36 inches from the top, centered on the door. Regardless of technique used, immediately after the gunner fires, he kicks the door in or pulls it out. He then pulls the shotgun barrel sharply upward and quickly turns away from the doorway to signal that the breach point has been reduced. This rapid clearing of the doorway allows the following man in the fire team a clear shot at any enemy who may be blocking the immediate breach site. See FM 3-06.11 for more information.

F-90.    When the assault team members encounter a door to a “follow-on” room, they should line up on the side of the door that gives them a path of least resistance upon entering. When the door is encountered, the first Soldier to see it calls out the status of the door, OPENED, or CLOSED. If the door is open, Soldiers should never cross in front of it to give themselves a path of least resistance. If the door is closed, the number-one man maintains security on the door and waits for the number-two man to gain positive control of the number-one man. The number-one man begins the progressive breaching process by taking his nonfiring hand and checking the doorknob to see if it is locked. If the door is unlocked, the number-one man (with his hand still on the door) pushes the door open as he enters the room. If the door is locked, the number-one man releases the doorknob (while maintaining security on the door) and calls out for the breacher, BREACHER UP.

F-91.    Once the breacher arrives at the door (with round chambered), he places the muzzle of the shotgun at the proper attack point, takes the weapon off safe, and signals the number-two man by nodding his head. At that time, the number-two man (with one hand maintaining positive control of the number-one man) takes his other hand (closest to the breacher) and forming a fist, places it within the periphery of the breacher and pumps his fist twice saying, READY BREACH. This action allows the breacher to see if a flashbang or grenade is to be used. Once the breacher defeats the door, he steps aside and allows the assault team to enter. He then either assumes the position of the number-four man if he is acting as a member of the assault team or remains on call as the breacher for any follow-on doors. He should keep the shotgun magazine full at all times. There may be numerous doors, and stopping to reload will slow the momentum of the assault.

 

NOTE:  The shotgun should not be used as a primary assault weapon because of its limited magazine capacity and the difficulty of reloading the weapon.

Exterior Walls

F-92.    One of the most difficult breaching operations for the assault team is reducing masonry and reinforced concrete walls. C4 is normally used for explosive reduction because it is safe, easy to use, and readily available. Engineers are usually attached to the platoon if explosive reduction operations are expected. The attached engineers will conduct the reduction themselves or provide technical assistance to the Infantrymen involved. The typical thickness of exterior walls is 15 inches or less, although some forms of wall construction are several feet thick. Assuming that all outer walls are constructed of reinforced concrete, a rule of thumb for reduction is to place 10 pounds of C4 against the target between waist and chest height. When detonated, this charge normally blows a hole large enough for a man to go through. On substandard buildings, however, a charge of this size could rubble the building. When explosives are used to reduce windows or doors, the blast should eliminate any booby traps in the vicinity of the window or doorframe. See FM 3-06.11 for information concerning demolitions.

Charge Placement

F-93.    Place the charges (other than shape charges) directly against the surface that is to be reduced. When enemy fire prevents an approach to the wall, a potential technique is to attach the charge, untamped, to a pole and slide it into position for detonation at the base of the wall. Small-arms fire will not detonate C4 or TNT. Take cover before detonating the charge.

Tamping

F-94.    Whenever possible, explosives should be tamped or surrounded with material to focus the blast to increase effectiveness. Tamping materials could be sandbags, rubble, desks, chairs, and even intravenous bags. For many exterior walls, tamping may be impossible due to enemy fire. An untamped charge requires approximately twice the explosive charge of a tamped charge to produce the same effect.

Second Charges

F-95.    Charges will not cut metal reinforcing rods inside concrete targets. If the ROE permit, hand grenades should be thrown into the opening to clear the area of enemy. Once the area has been cleared of enemy, the reinforcing rods can be removed using special steel-cutting explosive charges or mechanical means.

Door Charges

F-96.    Various charges can be utilized for explosive reduction of doors. Leaders must conduct extensive training on the use of the charges to get proper target feedback.

F-97.    The general-purpose charge, rubber band charge, and the flexible linear charge are field-expedient charges that can be used to reduce interior and exterior doors. These charges give the breach element an advantage because they can be made ahead of time and are simple, compact, lightweight, and easy to emplace. See FM 3-06.11 for more information.

General-Purpose Charge

F-98.    This charge is the most useful ready charge for reducing a door or other barrier. It can cut mild steel chain and destroy captured enemy equipment. To construct the general purpose charge—

– Take a length of detonation cord about 2 feet long. Using another length of detonation cord, tie two uli knots around the 2-foot long cord.

n         The uli knots need to have a minimum of six wraps and be loose enough for them to slide
along the main line, referred to as an uli slider.

n         Trim the excess cord from the uli knots and secure them with tape.

– Cut a block of C4 explosive to a 2-inch square.

– Tape one slider knot to each side of the C4 block, leaving the length of detonation cord free to slide through the knots.

F-99.    To place the charge, perform the following:

– To reduce a standard door, place the top loop of the charge over the doorknob. Slide the uli knots taped to the C4 so the charge is tight against the knob.

– Prime the loose ends of the detonation cord with an MDI firing system and detonate.

NOTE:  To cut mild steel chain, place the loop completely around the chain link to form a girth hitch. Tighten the loop against the link by sliding the uli knots.

Rubber Band Charge

F-100. The rubber band charge is an easily fabricated lightweight device that can be used to remove the locking mechanism or doorknob from wooden/light metal doors, or to break a standard-size padlock at the shackle. To construct the rubber band charge—

– Cut a 10-inch piece of detonation cord and tie an overhand knot in one end.

– Using another piece of detonation cord, tie an uli knot with at least eight wraps around the first length of cord.

– Slide the uli knot tightly up against the overhand knot. Secure it in place with either tape or string.

– Loop a strong rubber band around the base of the uli knot tied around the detonation cord.

– Tie an overhand knot in the other end of the cord to form a pigtail for priming the charge.

F-101. To place the charge, attach the charge to the doorknob (or locking mechanism) by putting the loose end of the rubber band around the knob. The charge must be placed between the knob and the doorframe. This ensures the explosive is over the bolt that secures the door to the frame.

Flexible Linear Charge

F-102. The simplest field-expedient charge for reducing wooden doors is the flexible linear charge. See Tables F-3 and F-4 for charge use and system components. It can be made in almost any length and is easily carried until needed. It is effective against hollow-core, particle-filled, and solid wood doors. When detonated, the flexible linear charge cuts through the door near the hinges

F-103. To construct the flexible linear charge, lay out a length of double-sided contact tape with the topside adhesive exposed. Place the necessary number of strands of detonation cord down the center of the double-sided tape, pressing them firmly in place. Military detonation cord has 50 grains of explosives per foot and there are 7,000 grains in a pound. Most residential doors are 80 inches tall. Commercial doors are 84 inches tall. This must be considered when calculating the quantities of explosives, overpressure, and MSDs. For hollow-core doors, use a single strand; for particle-filled doors, use two strands; and for solid wood doors, use three strands. If the door type is unknown, use three strands. One of the strands must be cut about a foot longer than the others and should extend past the end of the double-sided tape. This forms a pigtail where the initiating system is attached once the charge is in place. Cover the strands of detonation cord and all the exposed portions of the double-sided tape with either sturdy single-sided tape or another length of double-sided tape. Roll the charge, starting at the pigtail, with the double-sided tape surface that is to be placed against the door on the inside.

F-104. At the breach site, place the charge straight up and down against the door tightly. If it is too short, place it so it covers at least half of the door’s height. Prime and fire the charge from the bottom.

Table F-3. Charges.

Charge

Obstacle

Explosives Needed

Advantages

Disadvantages

Wall breach charge (satchel or U-shaped charge) Wood, masonry, brick, and reinforced concrete walls – Detonation cord

– C4 or TNT

– Easy and quick to make

– Quick to place on target

– Does not destroy rebar

– High overpressure

– Appropriate attachment methods needed

– Fragmentation

Silhouette charge Wooden doors (creates man-sized hole); selected walls (plywood, sheet-rock, CMU) Detonation cord – Minimal shrapnel

– Easy to make

– Makes entry hole to exact specifications

– Bulky; not easily carried
General purpose charge Door knobs, mild steel chain, locks, and equipment – C4

– Detonation cord

– Small, lightweight

– Easy to make

– Very versatile

Other locking mechanisms may make charge ineffective
Rubber strip charge Wood or metal doors (dislodges doors from the frame); windows with a physical security system – Sheet explosive

– Detonation cord

– Small, lightweight

– Quick to place on target

– Uses small amounts of explosives

 
Flexible linear charge Wooden doors (widow cuts door along the length of the charge) Detonation cord – Small, lightweight

– Quick to place on target

– One man can carry several charges

– Defeats most doors regardless of locking systems

Proper two-sided adhesive required
Doorknob charge Doorknobs on wood or light metal doors Detonation cord or flexible linear shaped charge – Small, lightweight

– Easily transported

– Quick to place on door

Other locking mechanisms may make charge ineffective
Chain-link ladder charge Chain link fence (rapidly creates a hole large enough to run through) – C4

– Detonation cord

Cuts chain link quickly and effectively Must stand to emplace it

 

Table F-4. Firing system components.

Firing System Components
Time system 2 x M81 or M60; time fuze or M-14; 2 x M7 caps; detonation cord loop; red devil (detonation cord connector)
Command detonated 2 x M81; 2 x shock tube with caps (M11 or M12); detonation cord loop; red devil (desired length)
Delay system 1 x M81 or M60 (gutted); black adapter cap; direct shoot shock tube (NONEL); M11 MDI; detonation cord loop; red devil (STI may be used instead of a direct shoot with an M60)

Explosive Safety Factors

F-105. When employing explosives during breaching operations, leaders must consider three major safety factors: overpressure; missile hazard; and minimum safe distance requirements.

1 – Overpressure

F-106. Overpressure is the pressure per square inch (PSI) released from the concussion of the blast, both outside and into the interior of the building or room, that can injure, incapacitate, or kill.

2 – Missile Hazard

F-107. Missile hazards are fragmentation or projectiles sent at tremendous speed from the explosion area. This occurs from either the charge or target being breached.

3 – Minimum Safe Distance Requirements

F-108. When using explosives in the urban environment, Soldiers must consider the presence of noncombatants and friendly forces. Additionally, there are many hazardous materials located in the urban environment, including chemicals and construction materials. There is always a risk of secondary explosions and fires when employing explosive breaching techniques.

 

Caution

Always handle explosives carefully. Never divide responsibility for preparing, placing, priming, and firing charges. Always use proper eye and ear protection and cover exposed skin to prevent injuries. Explosives may produce hazardous fumes, flames, fragments, and overpressure. Use AR 385-63, FM 5-34, FM 5-250, and risk assessment to determine minimum safe distances (MSDs). Take into consideration whether the door is flush or receded when considering MSD.

ReducE Booby Traps

F-109. Soldiers must be aware of the threat presented by booby traps that can be found in any operating environment in which the platoon might operate. The platoon must receive sufficient training to recognize locations and items that lend themselves to booby-trapping, striking a balance between what is possible and what is probable. See FM 20-32 for more information on booby traps and expedient devices.

F-110. When dealing with booby traps, the following rules and safety procedures can save lives:

– Suspect any object that appears to be out of place or artificial in its surroundings. Remember, what you see may well be what the enemy wants you to see. If you did not put it there, do not pick it up.

– Examine mines and booby traps from all angles, and check for alternative means of detonating before approaching them.

– Ensure that only one man works on a booby trap.

– Do not use force. Stop if force becomes necessary.

– Do not touch a trip wire until both ends have been investigated and all devices are disarmed and neutralized.

– Trace trip wires and check for additional traps along and beneath them.

– Treat all parts of a trap with suspicion, because each part may be set to actuate the trap.

– Wait at least 30 seconds after pulling a booby trap or a mine. There might be a delay fuse.

– Mark all traps until they are cleared.

– Expect constant change in enemy techniques.

– Never attempt to clear booby traps by hand if pulling them or destroying them in place is possible and acceptable.

F-111. Booby traps might be found in recently contested areas, so no items or areas that have not been cleared should be considered safe. By anticipating the presence of traps, it might be possible to isolate and bypass trapped areas. If this is not possible, employ countermeasures such as avoiding convenient and covered resting places along routes where mines or other explosive devices can be located. Collective training in booby-trap awareness and rapidly disseminating booby-trap incident reports to all levels is vital. This allows Soldiers to develop an understanding of the enemy’s method of operation and a feel for what might or might not be targets.

Indications and Detection

F-112. Successful detection depends on two things: being aware of what might be trapped and why, and being able to recognize the evidence of setting. The first requirement demands a well developed sense of intuition; the second, a keen eye. Intuition is gained through experience and an understanding of the enemy’s techniques and habits. A keen eye is the result of training and practice in the recognition of things that might indicate the presence of a trap.

F-113. Detection methods depend on the nature of the environment. In open areas, methods used to detect mines can usually detect booby traps. Look for trip wires and other signs suggesting the presence of an actuating mechanism. In urban areas, mine detectors are probably of little use. The platoon will have to rely on manual search techniques and, if available, special equipment. The presence of booby traps or nuisance mines is indicated by—

– Disturbance of ground surface or scattered, loose soil.

– Wrappers, seals, loose shell caps, safety pins, nails, and pieces of wire or cord.

– Improvised methods of marking traps, such as piles of stones or marks on walls or trees.

– Evidence of camouflage, such as withered vegetation or signs of cutting.

– Breaks in the continuity of dust, paint, or vegetation.

– Trampled earth or vegetation; foot marks.

– Lumps or bulges under carpet or in furniture.

Reduction Methods

F-114. Reducing booby traps and nuisance mines in AOs is done primarily by engineers, especially in secured areas. However, some booby traps may have to be cleared by Infantry Soldiers to accomplish a mission during combat. The method used to disarm a trap depends on many things including, time constraints, personnel assets, and the type of trap. A trap cannot be considered safe until the blasting cap or the detonation cord has been removed from the charge.

F-115. Use the safest method available to neutralize a trap. For example, if the firing device and the detonation cord are accessible, it is usually safer to cut the detonation cord. This method does not actuate the trap, but inserting pins in the firing device might. Unit resources or locally-manufactured or acquired aids are often used to clear traps. In areas with a high incidence of booby traps, assemble and reserve special clearing kits. Mark all booby traps found.

F-116. Nonexplosive traps are typically used in tropical or rain forest regions. Ideal construction materials abound and concealment in surrounding vegetation is relatively easy. No prescribed procedures exist for clearing nonexplosive traps. Each trap must be cleared according to its nature.

 

Section IIi — ObsTAcle EMPLOYMENT

F-117. Obstacles are used to reinforce the terrain. When combined with fires, they disrupt, fix, turn, or block an enemy force. Obstacles are used in all operations, but are most useful in the defense. Leaders must always consider what materials are needed and how long the obstacle will take to construct. See FM 5-34 for detailed instructions on specific types of obstacle construction methods.

F-118. A primary concern for the platoon in the defense is to supplement their fortified positions with extensive protective obstacles, both antipersonnel and antivehicle (particularly antipersonnel).

Antipersonnel obstacles, both explosive and nonexplosive, include all those mentioned in Section I (such as wire entanglements, antipersonnel mines, and field expedient devices), and are used to prevent enemy troops from entering a friendly position. Antipersonnel obstacles are usually integrated with fires and are close enough to the fortification for adequate surveillance by day or night, but beyond effective hand grenade range. Obstacles are also used within the position to compartmentalize the area in the event outer protective barriers are breached.

F-119. In the offense, the platoon/squad uses obstacles to—

– Aid in flank security.

– Limit enemy counterattack.

– Isolate objectives.

– Cut off enemy reinforcement or routes of withdrawal.

F-120. In the defense, the platoon uses obstacles to—

– Slow the enemy’s advance to give the Infantry platoon more time to mass fires on him.

– Protect defending units.

– Canalize the enemy into places where he can more easily be engaged.

– Separate the enemy’s tanks from his Infantry.

– Strengthen areas that are lightly defended.

Mines

U.S. NATIONAL POLICY ON ANTIPERSONNEL LAND MINES

On 16 May 1996, The President of the United States announced a national policy that eliminates or restricts the use of antipersonnel land mines, beginning with those that do not self-destruct, but eventually including all types. This policy is now in effect. It applies to all Infantry units either engaged in, or training for, operations worldwide.

Current U.S. policy allows the use of non-self-destructing antipersonnel land mines only along internationally recognized national borders or in established demilitarized zones, specifically for the defense of South Korea. Such mines must be within an area having a clearly marked perimeter. They must be monitored by military personnel and protected by adequate means to ensure the exclusion of civilians.

U.S. national policy also forbids U.S. forces from using standard or improvised explosive devices such as booby traps.

Except for South Korea based units and units deploying there for designated exercises, this policy specifically forbids all training on or actual employment of inert M14 and M16 antipersonnel land mines. Policy applies at the unit’s home station and at Combat Training Centers, except in the context of countermine or de-mining training. No training with live M14 mines is authorized, and training with live M16 mines is authorized only for Soldiers actually on South Korean soil.

This policy does not affect the standard use of antivehicular mines. Nor does it affect training and use of the M18 Claymore mine in the command detonated mode.

When authorized by the appropriate commander, units may still use self-destructing antipersonnel mines such as the ADAM. Authorized units may also continue to emplace mixed minefields containing self-destructing antipersonnel land mines and antivehicular land mines such as MOPMS or Volcano.

The terms “mine”, “antipersonnel obstacle”, “protective minefield”, or “minefield” contained in this FM should not be construed to mean an obstacle that contains non-self-destructing antipersonnel land mines or booby traps. Also, all references to antipersonnel mines and the employment of minefields should be considered in accordance with national policy that limits the use of non-self-destructing antipersonnel land mines.

 

F-121. Mines are one of the most effective tank and personnel killers on the battlefield. The type of minefield that a platoon or squad most commonly emplaces is the hasty protective.

F-122. It is important to distinguish the difference between the types of minefield and the means of emplacement. Volcano, Modular Pack Mine System (MOPMS), standard-pattern, and row mining are not types of minefields; they are just some of the means used to emplace tactical, nuisance, and protective minefields. They may also be the method of emplacement that is replicated by a phony minefield. Land-based mines and munitions are hand-emplaced, remote-delivered, air-delivered, or ground-delivered (Table F-5). FM 20-32 provides detailed instructions on the installation and removal of U.S. mines and firing devices.

Table F-5. Mine delivery methods.

Delivery Method Characteristics
Hand-emplaced Require manual arming and are labor-, resource-, and transport-intensive.
Remote- and Air-delivered Require less time and labor; however, they are not as precisely placed as hand-emplaced mines and munitions.
Ground-delivered Less resource-intensive than hand-emplaced mines. They are not precisely placed; however, the minefield boundaries are.

Scatterable Mines

F-123. SCATMINEs are laid without regard to a classical pattern. They are designed to be delivered remotely by aircraft, artillery, missile, or a ground dispenser. All U.S. SCATMINEs have a limited active life and self-destruct (SD) after that life has expired. The duration of the active life varies with the type of mine and the delivery system.

F-124. SCATMINEs enable minefield emplacement in enemy-held territories, contaminated territories, and in most other areas where it is impossible for engineers or the platoon to emplace conventional minefields. They may be used to support the platoon’s mission by turning, fixing, disrupting, and blocking the enemy. However they are used, they must be planned and coordinated to fit into the overall obstacle plan. Characteristics of AP SCATMINE systems are listed in Table F-6. Table F-7 lists AT SCATMINE characteristics. SCATMINE placement authority is shown in Table F-8.

Table F-6. Characteristics of AP SCATMINE systems.

Mine

Delivery System

DODIC

Arming Time

Fuse

Warhead

AHD

SD Time

Explosive Weight

Mine Weight

Number of Mines

M67

155-mm artillery (ADAM)

D502

within 1 min after ground impact

trip wire

bounding frag

20%

4 hr

21 g

Comp A5

540 g

36 per M731 projectile

M72

155-mm artillery (ADAM)

D501

within 1 min after ground impact

trip wire

bounding frag

20%

48 hr

21 g

Comp A5

540 g

36 per M692 projectile

BLU 92/B

USAF (Gator)

K291

K292

K293

2 min

trip wire

blast frag

100%

4 hr

48 hr

15 days

540 g

Comp B4

1.44 kg

22 per CBU 89/B dispenser

M77

MOPMS

K022

2 min

trip wire

blast frag

0%

4 hr (recycle up to 3 times)

540 g

Comp B4

1.44 kg

4 per M131 dispenser

Volcano

Ground/

air

K045

2 min

trip wire

blast frag

0%

4hr

48 hr

15 days

540 g

Comp B4

1.44 kg

1 per M87 canister

 

Table F-7. AT SCATMINE characteristics.

Mine

Delivery System

DODIC

Arming Time

Fuse

Warhead

AHD

SD Time

Explosive Weight

Mine Weight

Number of Mines

M73

155-mm artillery (RAAM)

D503

within 1 min after ground impact

magnetic

M-S plate

20%

48 hr

585 g

RDX

1.7 kg

9 per M718 projectile

M70

155-mm artillery (RAAM)

D509

within 1 min after ground impact

magnetic

M-S plate

20%

4 hr

585 g

RDX

1.7 kg

9 per M741 projectile

BLU 91/B

USAF (Gator)

K291

K292

K293

2 min

magnetic

M-S plate

NA

4 hr

48 hr

15 days

585 g

RDX

1.7 kg

72 per CBU 89/B dispenser

M76

MOPMS

K022

2 min

magnetic

M-S plate

NA

4 hr (recycle up to 3 times)

585 g

RDX

1.7 kg

17 per M131 dispenser

Volcano

Ground/

air

K045

2 min

30 sec

magnetic

M-S plate

NA

4 hr

48 hr

15 days

585 g

RDX

1.7 kg

5 per M87 canister; 6 per M87A1 canister

 

Table F-8. SCATMINE emplacement authority.


Scatterable Mine System
Emplacement Authority
Ground- or artillery-delivered, with self-destruct time greater than 48 hours (long duration). The corps commander may delegate emplacement authority to division level, which may further delegate to brigade level.
Ground- or artillery-delivered, with self-destruct time of 48 hours or less (short duration). The corps commander may delegate emplacement authority to division level, which may further delegate to brigade level, which may further delegate to battalion level.
Aircraft-delivered (Gator), regardless of self-destruct time. Emplacement authority is normally at corps, theater, or army command level, depending on who has air-tasking authority.
Helicopter-delivered (Volcano), regardless of self-destruct time. Emplacement authority is normally delegated no lower than the commander who has command authority over the emplacing aircraft.
MOPMS when used strictly for a protective minefield. Emplacement authority is usually granted to the company or base commander. Commanders at higher levels restrict MOPMS use only as necessary to support their operations.

Modular Pack Mine System (MOPMS), Man-Portable

F-125. The man-portable, 162-pound, suitcase-shaped MOPMS dispenses a total of 21 mines (17 antitank mines and 4 antipersonnel mines). It propels them in a 35-meter, 180-degree semicircle from the container. Mines are dispensed on command using the M71 remote control unit (RCU) or an electronic initiating device such as the M34 blasting machine. When dispensed, an explosive propelling charge at the bottom of each tube expels mines through the container roof (Figure F-12). The Infantry platoon can use MOPMS to create a protective minefield or to close lanes in tactical obstacles. The safety zone around one container is 55 meters to the front and sides, and 20 meters to the rear. MOPMS has a duration of 4 hours, which can be extended up to three times for a total of 16 hours. Once mines are dispensed, they cannot be recovered or reused. If mines are not dispensed, the container may be disarmed and recovered for later use. The RCU can also self-destruct mines on command, allowing a unit to counterattack or withdraw through the minefield. The RCU can control up to 15 MOPMS containers or groups of MOPMS containers from a distance of 300 to 1,000 meters.

Figure F-12. MOPMS.

Hornet

F-126. The Hornet is a man-portable, nonrecoverable, AT/antivehicular, off-route munition made of lightweight material (35 pounds) that one person can carry and employ. It is capable of destroying vehicles by using sound and motion detection methods. It will automatically search, detect, recognize, and engage moving targets by using top attack at a standoff distance up to 100 meters. It can be a stand-alone tactical obstacle or can reinforce other conventional obstacles. It disrupts and delays the enemy, allowing long-range, precision weapons to engage more effectively. This feature is particularly effective in non-line-of-sight (LOS) engagements. It is normally employed by combat engineers, Rangers, and SOF. The remote control unit (RCU) is a handheld encoding unit that interfaces with the Hornet when the remote mode is selected at the time of employment. After encoding, the RCU can be used to arm the Hornet, reset its SD times, or destroy it. The maximum operating distance for the RCU is 2 kilometers.

Conventional Mines

F-127. Conventional mines are hand-emplaced mines that require manual arming. This type of mine laying is labor-, resource-, and transport-intensive. Soldiers emplace conventional mines within a defined, marked boundary and lay them individually or in clusters. They record each mine location so the mines can be recovered. Soldiers can surface lay or bury conventional mines and may place AHDs on AT mines. FM 21-75 has complete information on emplacement of conventional AT mines.

 

NOTE:  U.S. Soldiers can surface lay or bury AT mines and munitions and can place AHDs on hand-emplaced AT mines. Some countries employ conventional AP mines (with or without AHDs), but U.S. forces are not authorized to employ conventional AP mines (except on the Korean peninsula).

Antitank Mines

F-128. The M15 and M21 AT mines are used by U.S. forces. They are shown in Figure F-13. Their characteristics are listed in Table F-9.

Figure F-13. Antitank (AT) mines.

 

Table F-9. Characteristics of AT mines.

Mine

DODIC

Fuse

Warhead

AHD

Explosive Weight

Mine Weight

Mines per Container

M15 with M603 fuse K180 pressure blast yes 9.9 kg 13.5 kg

1

M15 with M624 fuse K180 (mine)

K068 (fuse)

tilt rod blast yes 9.9 kg 13.5 kg

1

M21 K181 tilt rod or pressure SFF yes* 4.95 kg 7.6 kg

4

*Conventional AHDs will not couple with this mine. However, the M142 multipurpose firing device can be emplaced under this mine.

Antipersonnel Mines

F-129. The M14 and M16 AP mines are used by U.S. forces on the Korean peninsula. They are also used by many other countries. These mines are shown in Figure F-14. Their characteristics are listed in Table F-10.

Figure F-14. Antipersonnel (AP) mines.

 

Table F-10. Characteristics of AP mines.

Mine

DODIC

Fuse

Warhead

AHD

Explosive Weight

Mine Weight

Mines per Container

M14 K121 pressure blast no 28.4 g 99.4 g

90

M16-series K092 pressure or trip wire bounding frag no 450 g 3.5 kg

4

Special-Purpose Munitions

F-130. Special-purpose munitions that the platoon might employ include the M18A1 Claymore and the selectable lightweight attack munition (SLAM).

M18A1 Claymore

F-131. The M18A1 Claymore (Figure F-15) is a fragmentation munition that contains 700 steel balls and 682 grams of composition C4 explosive. It weighs 1.6 kilograms and is command detonated.

F-132. When employing the Claymore with other munitions or mines, separate the munitions by the following minimum distances:

– Fifty meters in front of or behind other Claymores.

– Three meters between Claymores that are placed side by side.

– Ten meters from AT or fragmentation AP munitions.

– Two meters from blast AP munitions.

 

Figure F-15. M18A1 Claymore.

SLAM

F-133. The M4 SLAM is a multipurpose munition with an antitamper feature (Figure F-16). It is compact and weighs only 1 kilogram. It is easily portable and is intended for use against APCs, parked aircraft, wheeled or tracked vehicles, stationary targets (such as electrical transformers), small (less than 10,000-gallon) fuel-storage tanks, and ammunition storage facilities. The explosive formed penetrator (EFP) warhead can penetrate 40 millimeters of homogeneous steel. The SLAM has two models (the self-neutralizing [M2] and self-destructing [M4]). The SLAM’s four possible employment methods include: bottom attack, side attack, timed demolition, and command detonation.

Figure F-16. SLAM.

M93 Hornet

F-134. The M93 Hornet is an AT and antivehicular off-route munition made of lightweight material (35 pounds) that one person can carry and employ (Figure F-17). It is a nonrecoverable munition capable of destroying vehicles through the use of sound and motion detection. It will automatically search, detect, recognize, and engage moving targets by using top attack mode at a standoff distance up to 100 meters from the munition.

Figure F-17. M93 Hornet.

Hasty Protective Minefields

F-135. Neither AP nor AT mines are used in isolation. The majority of mine composition is designed against the most severe close-combat threat and the likelihood of that threat. The MOPMS automatically dispenses a mix of AT and AP mines.

F-136. In the defense, platoons lay hasty protective minefields to supplement weapons, prevent surprise, and give early warning of enemy advance. A platoon can install hasty protective minefields, but only with permission from the company commander. Conventional hasty protective minefields are reported to the company commander and recorded on DA Form 1355-1-R, Hasty Protective Row Minefield Record. The minefield should be recorded before the mines are armed. The leader puts the minefield across likely avenues of approach, within range of and covered by his organic weapons. If time permits, the mines should be buried to increase effectiveness, but they may be laid on top of the ground in a random pattern. The leader installing the minefield should warn adjacent platoons and tell the company commander of the minefield’s location. When the platoon leaves the area (except when forced to withdraw by the enemy), it must remove the minefield (if it uses recoverable mines) or transfer the responsibility for the minefield to the relieving platoon leader. Only metallic mines are used in conventional hasty protective minefields. Booby traps are not used in hasty protective minefields because they delay removal of recoverable mines. The employing Infantry platoon must make sure that the minefield can be kept under observation and covered by fire at all times.

F-137. After requesting and receiving permission to lay the minefield, the Infantry platoon leader reconnoiters to determine exactly where to place the mines. While the Soldiers are placing the mines, the Infantry platoon leader finds an easily identifiable reference point in front of the platoon’s position. A tree stump is used as the reference point in sample DA Form 1355-1-R shown in Figure F-18. The platoon leader records the minefield. The row of mines closest to the enemy is designated A, and the succeeding rows are B, C, and so on.

F-138. The ends of a row are shown by two markers. They are labeled with the letter of the row and number 1 for the right end of the row and number 2 for the left end of the row. The rows are numbered from right to left, facing the enemy. The marker can be a steel picket or wooden stake with a nail or a can attached so it can be found with a metallic mine detector.

Figure F-18. Sample DA Form 1355-1-R (hasty protective row minefield record).

F-139. The platoon leader places a marker at B-1 and records the azimuth and distance from the reference point to B-1 on DA Form 1355-1-R.

F-140. Next, from B-1 the platoon leader measures the azimuth and distance to a point 15 to 25 paces from the first mine in row A. He places a marker at this point and records it as A-1. The platoon leader then measures the distance and azimuth from A-1 to the first mine in row A and records the location of the mine. He then measures the distance and azimuth from the first mine to the second, and so on until all mine locations have been recorded as shown. The platoon leader gives each mine a number to identify it in the tabular block of DA Form 1355-1-R. When the last mine location in row A is recorded, the platoon leader measures an azimuth and distance from the last mine to another arbitrary point between 15 and 25 paces beyond the last mine. He places a marker here and calls it A-2. The platoon leader follows the same procedure with row B.

F-141. When the platoon leader finishes recording and marking the rows, he measures and records the distance and azimuth from the reference point to B-2 to A-2. If antitank mines are being used, it is recommended that they be used at the A-2/B-2 markers, because their large size facilitates retrieval.

F-142. The platoon leader now ties in the reference point with a permanent landmark that he found on the map. He measures the distance and the azimuth from this landmark to the reference point. The landmark might be used to help others locate the minefield should it be abandoned. Finally, he completes the form by filling in the tabular and identification blocks.

F-143. While the platoon leader is tying in the landmark, the Soldiers arm the mines nearest the enemy first (Row A). The platoon leader reports that the minefield is completed and keeps DA Form 1355-1-R. If the minefield is transferred to another platoon, the gaining platoon leader signs and dates the mines transferred block and accepts the form from the previous leader. When the minefield is removed, the form is destroyed. If the minefield is left unattended or abandoned unexpectedly, the form must be forwarded to the company commander. The company commander forwards it to be transferred at battalion to more permanent records.

F-144. When retrieving the recoverable mines, the Soldiers start at the reference point and move to B-1, using the azimuth and distances as recorded. They then move from B-1 to the first mine in row B. However, if B-1 is destroyed, they move from the reference point to B-2 using that azimuth and distance. They will now have to shoot the back azimuth from B-2 to the last mine. The stakes at A-1, B-1, A-2, and B-2 are necessary because it is safer to find a stake when traversing long distances than to find a live mine.

Wire Obstacles

F-145. The platoon normally employs wire obstacles as part of the protective obstacle plan in the defense. Wire obstacles include barbed-wire, triple-standard concertina, four-strand cattle fences, and tanglefoot. Construction methods for two of the more common wire obstacles that the platoon employs, triple standard concertina, and tanglefoot, are shown in Figures F-19 through F-23.  See FM 5-34 for more information on these and other wire obstacles.

Triple Standard Concertina Fence

F-146. The most common wire entanglement a platoon or squad may build is the triple standard concertina fence. It is built of either barbed wire concertina or barbed tape concertina. There is no difference in building methods. The material and labor requirements for a 300-meter triple standard concertina fence are—

– Long pickets – 160.

– Short pickets – 4.

– Barbed wire, 400-meter reels – 3.

– Rolls of concertina – 59.

– Staples – 317.

– Man-hours to erect – 30.

F-147. First, lay out and install pickets from left to right (facing the enemy). Put the long pickets five paces apart, and the short (anchor) pickets two paces from the end of the long pickets (Figure F-19). The enemy and friendly picket rows are offset and are placed 3 feet apart. Now lay out rolls of concertina. Place a roll in front of the third picket on the enemy side, and two rolls to the rear of the third picket on the friendly side. Repeat this step every fourth picket thereafter. Install the front row concertina and horizontal wire (Figure F-20). Place the concertina over the pickets. Install the rear row of concertina and horizontal wire. Install the top row of concertina and join the rear horizontal wire (Figure F-21).

 

Figure F-19. Triple standard concertina fence.

Figure F-20. Installing concertina.

Figure F-21. Joining concertina.

Concertina Roadblock

F-148. The concertina roadblock is placed across roadways and designed to block wheeled or tracked vehicles. The roadblock is constructed of 11 concertina rolls or coils placed together, about 10 meters in depth, reinforced with long pickets five paces apart. The rolls or coils should not be tautly bound allowing them to be dragged and tangled around axles, tank road wheels, and sprockets. Additionally, wire is placed horizontally on top of the concertina rolls or coils (Figure F-22).

 

Figure F-22. Eleven-row antivehicular wire obstacle.

Tanglefoot

F-149. Tanglefoot is used where concealment is essential and to prevent the enemy from crawling between fences and in front of emplacements (Figure F-23). The obstacle should be employed in a minimum width of 32 feet. The pickets should be placed at irregular intervals of 2 ½ feet to 10 feet. The height of the barbed wire should vary between 9 to 30 inches. Tanglefoot should be sited in scrub, if possible, using bushes as supports for part of the wire. On open ground, short pickets should be used.

Figure F-23. Tanglefoot.


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