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General

1. In rocky ground, digging trenches is often impossible or very difficult. If ‘bee-hive’

charges or rock drills and explosives are available, holes may be blasted in rock to give some degree of protection. More often it will be necessary to build sangars.

Sangars

2. Concealment. If sangars are to be used, considerable care should be taken to avoid siting them in view of any likely enemy approaches. Sangars will often have to be sited on reverse slope positions, with the inherent penalties for observation. Pla-toon sized sangars should not be used because of the difficulty of concealing them and their vulnerability to air strikes, artillery and mortar fire. Even a four man sangar is difficult to conceal if it is above any tree line. Every use should be made of camou-flage nets and background rocks to break up the outline of sangars and to disguise their straight edges. While sangars will provide protection from small arms fire and some mortar and artillery splinters, they may compromise the positions of friendly forces and attract fire. Additionally, a sangar without overhead cover will intensify the effect of any bombs and shells landing inside them.

3. Construction. Sangars should be properly built of the largest rocks available wedged securely together. The walls should be built with a slope on each face of 76° and, to prevent penetration by small arms fire, they must be not less than 0.75 metres thick at the top. An unstable wall is more of a liability than an asset, as the first shell burst or burst of small arms fire will collapse it onto the defenders. Even solidly constructed sangars will not stand up to a direct hit from heavy anti-armour weapons, but an outer wall may be constructed to cause such weapons to explode prematurely. The wall may both impede vision from fighting sangars and reduce arcs of fire. A layer of sandbags should if possible be built round the inside of the sangar and on top of the walls to prevent injury from stone chips and splinters. Overhead cover has to be added before the sangar can be considered fully effective. Simple examples of the right and wrong way to construct a sangar are at Figure 4-1.

4. Scale. Two sangars for each infantry section is the normal scale with three or four men in each. Communication between sangars is difficult unless there is sufficient soil to make shallow crawl trenches possible. Temporary flank or night protection pickets in section strength may build only one sangar to save time, but more perma-nent defences should consist for four man sangars for greater protection.

Snow Shelters

5. Defence in Snow. If the snow is deep enough, standard defensive positions can be dug. Snow shelters and sleeping bays should be constructed with narrow entrances, which must be covered with ground sheets or other windproof material; they will then be warm enough to sleep in provided the body is insulated by pine branches or an air mattress. AFM Vol IV Part 4 Cold Weather Operations has further details on the construction of trenches and shelters in the snow.

6. Links Between Shelters. Communication trenches should be dug in the snow as normal and then be covered with boards, wire netting or branches with snow piled on top. In some conditions the snow may freeze hard enough for the supports to be removed and concealed tunnels will then be left. If trenches are left open, they will quickly fill with new or blown snow and become useless, unless the inside can be glazed with a heat source to melt the snow which will seal the surface when it freezes again.

Figure 4-1. Dry Stone Walling for Sangars

7. Protection. The thickness of snow and ice needed to give protection against small arms fire is given in Figure 4-2 below.

Minimum Thickness

Serial Description for Protection

(metres)

(a) (b) (c)

1 Newly fallen snow (no wind) 4.0

2 Wind driven snow 3.0

3 Packed snow 2.0

4 Frozen snow/water mixture (snow-crete) 1.2

5 Ice concrete 0.4

Figure 4-2. Penetration of Small Arms Ammunition in Snow Notes:

a. Newly fallen snow provides little protection but is excellent camouflage for pre-viously prepared positions.

b. Wind driven snow is marginally more effective than newly fallen snow if com-pacted in drifts which can be encouraged by erecting barriers of wood or snow.

c. The protection provided by packed snow increases the harder it is packed.

d. Snowcrete is formed with a mixture of snow and water allowed to freeze.

e. Icecrete or ice concrete is made from a mixture of water and gravel or any other solid material which has been allowed to freeze.

Obstacles and Mines

8. Obstacle Plans. A simple obstacle plan will usually be effective in the mountains because roads are few and routes are narrow and restricted. Most mountain roads cross numerous bridges and culverts, which can be demolished. In many cases the road can be cut even more effectively by well sited craters, often in series on a hill cut. Such demolitions can be extremely difficult to repair, particularly on a bend.

9. Blocking Routes. Where defended positions border frozen lakes or rivers, a pre-pared charge on the ice may produce a moat as an obstacle. Routes can be blocked by creating a landslide or rockfall on them. However, this is not usually as effective as cutting the route unless:

a. A very large quantity of explosive and specialized items (eg shaped charges) can be used.

b. The route is extremely restricted running through a narrow defile or a tunnel.

10. Wire Obstacles. Wire obstacles can be effective, especially when used in combi-nation with steep slopes, but they must be securely anchored. Anchorage may be a problem. On stony ground, rocks may be used to anchor the concertinas of wire. In snow, where it is not deep, conventional wire obstacles can be used but may need extra long pickets. If there is a heavy fall or one is expected, then a fence which can rest on top of the snow and be repositioned after each new fall is needed. Such techniques, including the Lapland Fence which makes use of barbed wire instead of concertinas, are described in AFM Cold Weather Operations. The possibility of burrowing under obstacles placed on the snow, particularly at night, should not be overlooked.

11. Minefields. Large barrier or defensive minefields are unlikely to be used in moun-tains; instead nuisance mining may be used on routes and exists thereby inhibiting both armour and artillery from deploying on to any areas of flat ground. On rocky ground mines may have to be surface laid and then camouflaged. Because move-ment options are restricted by terrain, there is scope for effective use of anti-person-nel mines and booby traps, including those initiated by delayed action fuses. The use of booby traps will have to be authorized by the appropriate level of tactical command. Mines laid in snow require special consideration (See AFM Cold Weather Operations). In mountains where movement tends to be canalized, mines can pose a threat to friendly troops as well as to the enemy; their use should be carefully con-trolled and whenever possible they should be lifted when they become redundant.

12. Mines and Other Defence Stores. Provision has to be made in the logistic sup-port plan for supplying sufficient mines and materiel for the construction of obstacles, minefield and other obstructions.

13. Camouflage and Concealment. Changes in mountain cover encountered in some areas makes camouflage and concealment more difficult. For example nets and vehicle paints designed for use in woodland, are unsuitable above the treeline. Similar problems occur above and below the snow line and provision has to be made for additional camouflage materiel and clothing when moving from one type of cover to another.

SECTION 2. MINOR TACTICS FOR USE IN SNOW CONDITIONS