SPMAGTF(X) MOUT Training Program of Instruction

Subterranean Patrols

INTRODUCTION

GAIN ATTENTION

During World War II German soldiers utilized subterranean avenues of approach to infiltrate enemy positions. More recently, Chechen rebels successfully utilized the below ground levels of Grozny in operations against the Russian Army. Given that all cities contain subterranean areas and the high value of these areas in conducting military operations, it is very likely that Marines will be required to conduct patrols below the surface during future MOUT.

PURPOSE

The purpose of this period of instruction is to familiarize the Marine with the considerations and conduct of subterranean patrols.

INDIVIDUAL TRAINING STANDARDS

MISSION PERFORMANCE STANDARDS

TERMINAL LEARNING OBJECTIVE

Without the aid of references and in accordance with the MCWP 3-35.3, the student will demonstrate the proper techniques for clearing and securing a subterranean area.

ENABLING LEARNING OBJECTIVE

1. Know the seven types of subterranean features.
2. Know the two types of underground networks.
3. Know the disadvantages of conducting subterranean operations.
4. Know what type of equipment all Marines should carry during subterranean operations.
5. Know basic tunnel clearing procedures.

METHOD AND MEDIA

This period of instruction will be taught through the lecture and demonstration method.

TESTING

This period of instruction will be evaluated through practical application during situational training exercises.

TRANSITION

BODY

1. Underground Features: Commanders and their staff should always seek information on the nature and the location of subterranean features. Every Marines should always report all findings of underground tunnels, subways, sewer systems, and waterways to higher headquarters. Common subterranean areas found in an urban environment are as follows:

a. Underground transportation systems such as subways, trains, and pedestrian and vehicular tunnels.
b. Underground commercial structures such as malls and parking lots.
c. Maintenance access tunnels.
d. Electric, gas, telephone, water and other utility lines.
e. Pedestrian passages.
f. Sewer drainage systems and waterways.
g. Natural underground passages.

2. Types of Underground Networks: There are two types of underground networks that allow easy access and movement below the surface. They are sewers and subways.

a. Sewers: Sewers are separated into three types; sanitary, storm, or combined systems. Sanitary sewers carry human waste and are usually too small to permit entry. Storm sewers function to remove rain water from the street networks and are usually large enough for people and small vehicles to enter. They are usually dry when there has been no recent precipitation. Combined systems are usually found in older cities and merge the two functions of sanitary and storm water removal. Combined systems normally remain partially full at all times. All sewers generally follow street patterns and flow in a slightly downward slope that may increase as the sewer progresses down flow.

b. Subways: Most large cities have extensive subway systems of various sizes. Subways are usually build under major roadways and may have potentially hazardous electrified and power leads. Subways often have underground stations that connect to subterranean malls or storage areas. Utility and maintenance tunnels are often found near subways. Older cities may have extensive catacombs below street level and underneath buildings.

3. Disadvantages of Subterranean Features: There are two major disadvantages in conducting subterranean operations. One is natural and the other combat related. a. Natural Disadvantages

1) Sewers may fill rapidly during rainstorms. This is especially true if the city's electrical system is off-line and drainage pumps are not operating.
2) Snow melt and the resulting run off may restrict day operations in underground systems during cold weather MOUT.
3) Sanitary sewers that have become blocked may build up methane gas which is flammable and explosive. Also, smoke and other heavy substances may displace oxygen. Poor ventilation can be a problem in many types of subterranean areas. Squad leaders must be alert to the signs of lack of oxygen and always know the shortest route to fresh air.
4) Underground areas are breeding grounds for disease and rodents. Personal hygiene and immunization are especially important here. Small wounds can easily become infected.
5) The lack of light and near total darkness in many subterranean areas will have a negative psychological effect on personnel and will make navigation difficult. Utilizing illumination sources may disclose the friendly position if not used cautiously during tunnel clearing operations.

b. Combat Related Disadvantages

1) The noise and effect of weapons systems will be amplified inside the subterranean area. Bullets and shrapnel will ricochet off walls and along the sides of tunnels. Noise may temporarily deafen Marines.
2) Adequate cover and concealment is often not available.
3) The effects of chemical agents will linger for a longer period of time due to the lack of wind and sunlight necessary to break down the chemical compounds.
4) Flame weapons will become more dangerous inside subterranean areas as they will follow the walls around corners. Also, the effects of flame weapon oxygen consumption must be considered.

4. Equipment: Combat leaders must carefully select the gear to be taken into an underground area. 782 gear and equipment may snag on unseen obstacles and much of this gear may be left behind depending on the size of the tunnel system. METT-T should be analyzed and common sense applied when selecting equipment. As in any urban operations, overburdened Marines will have a difficult time negotiating obstacles and will fatigue quickly.

a. The following guidelines should be used when equipping a tunnel-clearing team:

1) The patrol leader should carry a small red lens flashlight and a notebook for recording information and sketching a map of the subterranean area.
2) All Marine should carry field protective masks, white lends flashlights, gloves and their personnel weapons. Helmets should be worn to protect the head from unseen obstructions. Body armor should also be worn unless the tunnel is extremely small. M-9 pistols are the preferred weapon for tunnel teams as they are easily employed with one hand and are very maneuverable in a tight area. Extra magazines should be carried. If available, IR chem lights and NVGs work well together. The patrol leader could use the IR light on the AN/PVS-7B night vision device to read notes and maps when there is no other light source available.
3) If there is a possibility of chemical agents in the subterranean area, the point man should carry the M-256 chemical agent detection kit.
4) The patrol leader should carry special equipment including a tool for opening manhole covers and for removing mines or booby traps. The patrols should also have a means for marking their route (spray paint, chalk, chem lights, dummy cord, etc.). A field telephone and several hundred meters of communications wire should be carried to provide a communications link to the entrance of the subterranean area.
5) Ensure that slings are taped down or use 550 cord as a replacement sling to reduce noise inside the tunnel.
6) When entering small tunnels, leave unnecessary gear behind, use follow-on forces to bring it up.
7) The patrol leader must plan to spread load equipment throughout the clearing team throughout the patrol.

5. Task Organization: A squad or fire team leader must task organize his Marines into an assault element, a support element and a security element. The squad leader must keep the number of Marines in the tunnel team to a minimum as subterranean areas are normally confined spaces. Too large a tunnel team makes for decreased command and control as well as interference among the team members. If a large patrol is necessary to meet METT-T requirements; then the squad leader should break the patrol into small point elements, a main body, and a small rear security element. Dispersion is important to maintain noise discipline and to prevent multiple casualties from a single attack.

6. Basic Tunnel Clearing Procedures: Large underground systems should be cleared in the same manner as buildings or rooms. Underground combat will require light sources such as illumination grenades, flares, flashlights, chem lights and NVGs. A simple but effective illumination plan must be established prior to entry.

a. The tunnel clearing team first moves to the subterranean entrance. This entrance can be anything from a manhole cover to a large door or gateway. After opening the entrance, a 15 minute security check should be conducted to aid in detecting any enemy presence and to air out the tunnel. If enemy is detected, the team has the option of wither throwing a grenade through the entrance and sealing it off or assaulting to gain a foothold inside the tunnel.
b. For a vertical or semi vertical entrance, the point man enters with a rope tied around his waist. his mission is to make the initial check on the size and condition of the tunnel. After a ten minute (or other pre-determined time) period, the point man will return to the entrance. If he does not return, he is to be pulled up to the entrance immediately. One scenario is that the air quality is poor and the team may have to enter with gas masks on.
c. After the point man has secured the inside of the tunnel's entrance, the remainder of the team can enter. Security at the entrance should be maintained at all times.
d. When the team is moving the point man should be approximately 10 meters in front of the team leader. The remainder of the patrol should maintain a five meter interval. If there is fast moving water or slippery footing, the use of a safety line tied between personnel should be used. To improve footing, Marines should wrap "chicken wire" or "screen wire" to their boots.
e. As the tunnel clearing team progresses, the rear security element should mark the route. The point man should move steadily, always checking for booby traps and pieing off corners as they are approached. Point men should be rotated as space in the subterranean area allows.
f. Security halts should be conducted periodically to listen for the enemy, to conduct chemical agent tests, and to allow the team leader to draw a map of the underground area or to write notes.. If manholes to the surface are encountered, they should be opened to determine your location. Always check the tunnel wall next to a manhole as they are often marked to aid maintenance workers. The use of a mirror on a stick could also be used as the manhole may be covered by enemy fire. Never stop the patrol along a long portion of the tunnel. Always move to a turn or corner to conduct a security halt. This will provide at least some cover if enemy contact is made.
g. If an enemy located in the tunnel must be engaged, the tunnel team must maximize "violence of action". Employ bends or corners for cover. If encountered by a lone sentry, Marine should be prepared to eliminate him with a knife in order to maximize stealth.
h. Once the tunnel clearing team returns, all Marines should report to the platoon commander and participate in a detailed debrief in order to facilitate the timely reporting of accurate intelligence to higher headquarters. This intelligence is vital, as Marines may have to re-enter the same tunnel at a future time.
i. The tunnel clearing team members may be used by follow on forces as guides. However, the tunnel would have to be secured again once it has been left. A Claymore mine positioned at the limit of advance can provide a degree of security. But always remember that this method is not fool proof as it could always be removed by enemy forces.

7. Defending Tunnels and other Subterranean Areas: Tunnels can be blocked and secured in the same manner as buildings and rooms. Mines, booby traps, early warning devices, concertina wire, and mantraps may be employed. Obstacles should be covered by fire. Command detonated Claymore mines should also be employed to cover an obstacle belt. If Marines are to occupy fixed fighting positions inside a subterranean area, the position should be constructed on a platform to avoid exposure to flooding. Marines should be very cautious when employing light devices so as to not reveal their position to the enemy. The use of grenades, mines, and other explosives may have to be used sparingly as they can have an adverse effect on friendly forces. Common effects include ruptured eardrums and wounds from debris scattered in a confined space. Gases in sewers (generally methane) can be ignited by the blast effects of these munitions. If possible, Marines should be outside of the tunnel or out of range when grenades or demolitions are used.

QUESTIONS

SUMMARY

During this period of instruction we have examined the basic principles of conducting underground operations. Commanders and combat leaders must never neglect the unique qualities of subterranean areas and take measures to cover the various avenues of approach that exist in these systems. Creativity, initiative and boldness will enable marines to succeed in this difficult environment.

The MOUT Home Page Hot Links:

U.S. Army FM 90-10-1 An Infantryman's Guide to Combat in Built-up Areas (PDF)

Tunnel Rats (Subterranean operations in Vietnam)

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