1. Counter-mobility and survivability operations are a key role of the engineers and are carried into the water by the combat divers. Counter-mobility operations are conducted to support the manoeuvre commander's plan to fix and strike the enemy. The barrier plan is developed and coordinated at all levels with the manoeuvre commanders. The combat divers must understand the intention for the obstacles that they are putting in. Normally, at a water obstacle, the intent is to disrupt a crossing site, turn the enemy away from the site, or block the enemy from using a site. These intents require an increasing level of work and resources required to accomplish them. Obstacles are an important part of force protection and survivability. They mould the enemy to the commander's intent and increase the enemy's vulnerability while acting as a force multiplier.
2. Typical counter-mobility operations are:
a. denial of terrain and approaches;
b. flank protection; and c. rear area security.
3. The employment of combat engineering resources is key in the implementation of counter-mobility operations, and, as such, combat divers provide a valuable asset and means of execution. This chapter outlines typical tasks combat divers may be required to conduct to support counter-mobility operations and to enhance force survivability.
4. Counter-mobility Tasks. Combat divers' counter-mobility tasks are:
a. Putting in anti-tank landmines at crossing sites, below water and on the far bank. Mining of the home bank is not a diver specific task, but it could be done by divers.16
b. Putting in obstacles in the water and on the far bank, including cratering in the water.
c. Assisting in demolition tasks on infrastructure, such as bridges, docks or piers.
5. Reconnaissance. Combat divers may be used to conduct reconnaissance in support of a counter-move, withdrawal, denial, breaking contact, and flank protection. The majority of reconnaissance details are the same as those required for land based combat engineer tasks (Crossing Site Recce Report, E112B (DND 2106)). The reconnaissance must be coordinated with the commander's intent and support barrier, withdrawal, and counter-moves plans.
6. Obstacle Emplacement. The principles employed in obstacle emplacement on land can be applied in the water. Generally, obstacles used on land can be extended to or constructed at or below the waterline. Vehicle traction is greatly reduced in water due to the buoyancy of the vehicle and reduced friction on the bottom. This reduced traction affects the vehicle's ability to break obstacles or to climb exit banks. These characteristics need to be taken into account;
16 In principle, only the home bank should be mined in order to allow our forces to breach the obstacle more easily and to make it more difficult for the enemy forces to breach the mined area.
both to our advantage and to ensure that our obstacles are effective.17 Considerations when emplacing obstacles in the water are:
a. Obstacle intent, including what it is expected to stop or affect.
b. The action of currents, tides, and waves, which could make emplacement difficult and could move, bury, or destroy the obstacles.
c. Slope and nature of the banks or beach, and whether they could be used to augment other obstacles. A step cut into the bank may prevent a vehicle from exiting the water. Certain soils or sands may be effective obstacles with minimal preparation.
7. Obstacles that could be emplaced by combat divers are:
a. Submerged log booms with wire or spikes anchored to the river bed or shoreline.
17 Reduced ground-bearing pressure could mean that a pressure fuzed mine may not be set off.
b. Chain or SWR running between piles beneath the water line.
c. Concrete obstacles, normally prefabricated but sometimes improvised using highway barriers or curbs. These are difficult and time consuming to put into place with most of the work carried out above water to transport them to location and lower them off the boat, raft, or barge.
d. Steel obstacles, normally improvised from beams or railway tracks. They are normally pre-fabricated on shore and moved into place by boat, raft, or barge. The divers help to place them accurately on the bottom.
e. Wire obstacles, usually for dismounted soldiers.
8. Landmines. Combat divers will use anti-tank mines to extend tactical minefields into the water, close minefield lanes in advance of anti-tank scatterable mine closure, or to put in nuisance minefields at potential crossing sites. The principles, mine preparation techniques, patterns, and recording and marking procedures for underwater emplacement of mines are detailed in B-GL-361-009/FP-003, Mines And Booby Traps, Engineers. Mines will normally be laid in shallow water, less than the normal deep ford depth of the vehicles. This practice will ensure that the vehicles have sufficient ground-bearing pressure to activate pressure-fuzed mines. Mines are not required in deeper water as we are not trying to prevent the use of the middle of the waterway, just the entrances and exits.
9. Landmine Laying. Combat divers will normally put antitank mines in water that is shallow enough to avoid the use of CABA. Emplacing mines in the water is labour and time intensive. The planning rate for laying anti-tank mines is five mines per hour per diver. This estimate does not take into consideration the work required to protect the mines from the effects of exposure to water and depth, currents, and waves. The in-service anti-tank mine DM 21 does not require additional water proofing for use at these shallow depths.
It may need to be anchored against current, waves, or tides. Strong currents in deep water will prevent amphibious vehicle crossings (the intelligence officer will confirm go/no-go currents for enemy equipment). Ford crossings are not seriously affected by strong currents. Fixing mines to steel grates and pinning them down with spikes is an example of improvisation to meet the problems posed by currents.
10. Recording. Recording requires that combat divers improvise and adapt as required. It may be necessary to use at least two benchmarks on the bank for reference and recording. Benchmarks should be easily identifiable, clearly indicated on the minefield record, and placed above the high-water mark. An E122D (DND 2109), Minefield Completion Report will be completed and submitted through the chain of command for all underwater mining.
11. Landmine Emplacement Drills. When conducting mining operations in the water, the basic principles of working in echelon, staying behind armed mines, and one person per mine are applied. There are two methods generally used by combat divers to place and record mines in the water. For either drill, divers will be tended from the shore. Tending supports the diver. The tending line can be graduated and used as a measuring device for recording. The two drills typically used are:
a. linear drill; and b. half circle drill.
12. Linear Drill. This method will likely be used when extending rows from tactical minefields into the water. The general procedure and considerations are:
a. Establish a benchmark.
b. Establish a baseline on shore, running parallel to the water.
c. Pickets are driven in at intervals along the baseline. These will indicate rows or start points for bearings on which mines are placed.
d. Tended divers, with the pickets as a reference point, emplace mines in the specified design.
e. Mines will be armed as they are placed.
f. Accurate details for recording are maintained.
g. Upon completion, the baseline is removed and pickets driven flush to the ground.
13. Half Circle Drill. This method will likely be the most common method used. It applies itself well to nuisance mining. It is less time consuming than the linear drill. This method is similar to that of placing and recording anti-tank mines in protective minefields. The diver is sent out from a central point on a tending line that is graduated to indicate distance. The tender and supervisor keep the diver on a set bearing. The general procedures and considerations for this drill are:
a. establish a benchmark;
b. the diver is sent out with a prepared mine on a bearing;
c. he is controlled by the tender and supervisor;
d. mines are placed and armed; and e. minefield record is produced.
14. When using either of the above drills, a boat may be used to transport mines to divers.
15. Execution of Demolition Obstacles. Generally, combat divers will not execute these tasks, as they usually require large amounts of explosives, types of tools, equipment, and preparation. Combat divers may be used to assist other combat engineers in the reconnaissance and preparation of targets and target areas. In some situations, combat divers can attack a specific target, but these would be within our own areas. Combat divers are not trained nor equipped to conduct long-range patrols to attacks targets. In these situations, detailed reconnaissance, coordination of support, security, and a sound insertion and extraction plan are essential.
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