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Operations in Mountains

FM 90-3 Appendix F Desert Operations

Mountain operations are described in detail in FM 90-6. This appendix describes special conditions associated with operating in mountains such as those in the southern Sinai and on the shores of the Red Sea. It does not address tactics and techniques for mountain operations that are equally applicable to all mountains, except for the purpose of clarity.


Mountains are high and rugged, with very steep slopes. Valleys running into a range become more and more narrow with the sides becoming gradually steeper. Valleys are usually the only routes that allow ground movement of men and equipment at any speed or in any quantity. Water is nonexistent on hilltops and unusual in valleys except during flash floods after rains. Lateral ground communications are limited unless the force is moving across the spines of mountain ranges. Navigation may be difficult, as maps are likely to be inaccurate.


Troops operating in mountainous country must be in peak physical condition. Regardless of their normal physical condition, personnel operating in mountainous areas require additional stamina and energy. They must also possess the ability to conduct sustained physical exertion and recover from it quickly.

Acclimatization is described in Chapter 1. Acclimatization to height, which varies much more among individuals than that for heat, must also be considered for operations in mountains. Lack of oxygen at high altitudes can cause unacclimatized troops to lose up to 50 percent of their normal physical efficiency when operating in altitudes over 6,000 feet. Mountain sickness may occur at altitudes over 7,800 feet and is usually characterized by severe headache, loss of appetite, nausea and dizziness, and may last from 5 to 7 days. Troops can acclimatize by appropriate staging techniques. It may take several weeks to become completely acclimatized, depending on altitude and the individual’s personal physical reactions.

The risk of sunburn, particularly to the uncovered face, is greater in mountains than on the desert floor due to thinner atmosphere. Use antisunburn ointment and keep the face in shade around midday, using face nets or sweat rags. An individual camouflage net or scarf is particularly useful for this purpose. Recognition of heat illnesses in higher altitudes may not be as apparent as at lower altitudes because sweat evaporates very quickly. Measures to avoid dehydration and salt loss are extremely important. Daily temperature variations may be considerable making it necessary to ensure troops do not become chilled at night. Layering of clothing is essential. Troops who have been sweating heavily before the temperature starts to drop should take their wet shirts off and place them over relatively dry shirts and sweaters. Soldiers/marines should add layers of clothing as it gets colder and remove them as needed. This may have to be leader supervised and disciplined in the same manner as water consumption.

Requirements for hygiene areas important in mountainous areas as in the desert itself. Normal rocky ground will make it extremely difficult to dig any form of latrine so cover excrement with rocks in a specially marked area.


Infantry is the basic maneuver force in mountains. Mechanized infantry is confined to valleys and foothills (if these exist), but their ability to dismount and move on foot enables them to reach almost anywhere in the area. Airmobile infantry can also be extensively used. Consideration should be given to modifying the TOE of infantry units operating in barren mountains. A strong antitank platoon may not be necessary. However, the infantry requires extra radars and radios for the number of observation posts and separate positions that they may expect to occupy.

Mountains are not a good environment for tank and armored cavalry operations, because tanks and armored cavalry are unable to maximize their mobility, flexibility, and firepower.

Avenues of approach at ground level are few. Roads or trails are limited and require extensive engineer effort to maintain. Off-road trafficability varies from relatively easy to very difficult. Most movement and maneuver in this type of terrain is either by air or on foot. Unnecessary vertical foot or vehicle movement should be avoided. Rock slides and avalanches, although not as common as in high cold mountains, do exist and can restrict movement.

Air cavalry is the major reconnaissance means but they must guard against being ambushed by ground troops located at their own altitude or even higher. Security of units must include observation, especially at night, of all avenues of approach including those within the capabilities of skilled mountaineers.

It is relatively easier to conceal troops in barren mountains than on the desert floor due to rugged ground, deep shadows (especially at dawn and dusk), and the difficulties an observer encounters when establishing perspective. Carefully placed rocks can be used to hide equipment however, rocks can chip and splinter under small arms fire. The normal type camouflage net, which breaks up outline by shadow, maybe used rather than the overall cover normally used in the desert.

Helicopter units of all types can be used, although they maybe slightly inhibited by altitude and rugged terrain. Payloads and endurance are degraded due to density and attitude. Winds are turbulent with considerable fluctuations in air flow strength and direction, particularly on the lee side of mountains. These winds, combined with the terrain, produce extra strain on crews as they have little margin for error. Flight crews should receive training in these conditions before flying in operations under these conditions.

When using men on foot for navigation, use all available maps, the lensatic compass, and a pocket altimeter. The pocket altimeter is essentially a barometer, measuring height by means of varying air pressure. If a navigator can only establish his location in the horizontal plane by resection on one point, the altimeter tells him his height, and thus his exact position. The instrument must be reset at every known altitude as it is affected by fluctuations of air pressure. Air photographs can also be helpful if they are scaled and contoured.

Supply of water and ammunition and the evacuation of wounded, especially if helicopters cannot land, can complicate operations. Water and ammunition may have to be transported by unit or civilian porters using A-frames or other suitable devices, or even by animal transport such as camel or mule.


The objective in mountainous areas of operations is normally to dominate terrain from which the enemy can be pinned down and destroyed. Avenues of approach are normally few, with very limited lateral movement except by helicopter. Reconnaissance must be continuous using all available means, as enemy defensive positions will be difficult to find. Observation posts are emplaced on high ground, normally by helicopter.

When contact is made, airmobile infantry can be used to outflank and envelop the enemy while suppressive fires and close air support are placed on all suspected positions, especially on dominating ground. Engineers should be well forward to assist in clearing obstacles. If airmobile infantry is unable to outflank the enemy, it will be necessary to launch a deliberate attack.

Frontal attacks in daylight, even with considerable supporting frees, have a limited chance of success against a well-emplaced enemy. Flank attacks on foot take a lot of time. The best opportunity is at night or in very poor visibility, but progress of men on foot will be slow and objectives should be limited.

The force should make every effort to secure ground higher than enemy positions to allow the attack to be downhill. Mobile forces should select objectives to the enemy’s rear to kill the enemy as they reposition or counterattack. Foot mobile forces must seek adequate terrain (restrictive) to equalize the enemy’s mounted mobility advantage.

Air superiority is required to allow a continuous flow of supplies and combat support by helicopter. Friendly mobile units must concentrate to destroy enemy command and control, artillery, service support, and air defense assets. It may be possible to infiltrate to a position behind the enemy, preferably using the most difficult, and hence unlikely route. Although this is very slow, it normally has the advantage of surprise.

The importance of dominating terrain, together with the enemy’s knowledge that troops on the objective will be physically tired and dehydrated, makes an immediate counterattack likely. Supporting weapons must be brought forward at once, preferably by helicopter, and casualties removed by the same method.

Airmobile and attack helicopter units are well suited for pursuit operations. They can be used to outflank retreating enemy, and set up positions overlooking likely withdrawal routes. Small engineer parties can be emplaced to block defiles and interdict trails. Close air support and field artillery are used to reinforce airmobile and attack helicopter units and to counter efforts by enemy engineers to create obstacles.


A defense from a series of strongpoints is normal in hot mountains due to the need to hold dominating terrain and restrictions on ground mobility. Due to the amount of rock in the soil, it takes more time to prepare positions and normally requires engineer support.

It is necessary to hold terrain dominating avenues of approach. Any terrain that dominates a friendly position must either be held, or denied to the enemy by fire. It may be necessary to stock several days’ supplies, especially water, ammunition, and medical equipment in a position in case helicopters or supply vehicles are unable to reach it.

When a covering force is used, it is organized around cavalry reinforced with attack helicopters, supported by field and air defense artillery. Airmobile infantry operates on ridge lines. If the enemy closes on a battle position it is difficult to extract airmobile infantry, so sheltered landing sites nearby should be available. In any event, extractions must be covered by air or ground suppressive fires. Stay-behind observers should be used to call down field artillery fires on targets of opportunity or to report enemy activity. When tanks are a threat and terrain is suitable, the covering force is reinforced with tank-heavy units and antitank weapon systems.

Combat in the main battle area is usually a series of isolated actions fought from strongpoints on ridge lines and in valleys. Patrols are used extensively to harass the enemy and prevent infiltration; all possible routes must be covered. If the enemy attempts to outflank the friendly force, he must be blocked by attack helicopters, if available, or airmobile infantry.

Reserves should be kept centrally located and deployed by air to block or counterattack. If this is not possible, reserves may have to be split up and placed behind key terrain where they are available for immediate counterattack.

If retrograde operations are necessary, mountainous terrain is as good a place to conduct them as anywhere. More time is required to reconnoiter and prepare rearward positions, and they should be prestocked as much as possible. Unlike the desert floor where movement between positions is likely to cover relatively great distances, movement in these conditions is usually from ridge to ridge. Routes must be covered by flank guards, especially at defiles or other critical points, as the enemy will attempt to block them or cut off rear guards.


It may be difficult to find good gun positions at lower altitudes due to crest clearance problems-so high-angle fire is often used. The best weapons are light field artillery and mortars that are airmobile and can be manhandled so they can be positioned as high as possible.

Field artillery observation posts are emplaced on the highest ground available, although in low-cloud conditions it will be necessary to ensure that they are staggered in height. Predicted fire may be inaccurate due to rapidly changing weather conditions making observed fire a more sure method for achieving the desired results.

Like field artillery, there is limited use for self-propelled weapons in this environment, although some may be used in valleys. Airmobile towed weapons allow employment throughout the mountainous area of operations.

Major tasks for engineer, even in an airmobile force, are: construction, improvement, and route repair, and their denial to the enemy. Mining is important due to the limited number of routes. Lines of communication require constant drainage and possibly bridging to overcome the problem of flash flooding.

Because of the frequent interdictions of mountainous roadways, military police will experience multiple defile operations. Use temporary traffic signs to expedite traffic movement to the front. The number of stragglers may be expected to increase in this environment. Because of difficulty in resupply, the supply points for water, POL, food, and ammunition will become especially lucrative targets for enemy attack. Military police rear area security elements must develop plans for relief and for augmenting base defense forces.


Air transportation is the best CSS means in mountain operations due to its mobility. It may be limited by the weather, enemy activity, or the scarcity of landing sites, so there should be alternative means available. Terrain permitting, wheel-vehicle transportation should be employed as far forward as possible, using high-mobility vehicles off main mutes. Beyond the limits of wheel transport the only alternatives to CSS transport are animals (which may need to be acclimatized) or porters.

The composition and employment of trains in mountain operations are described in FM 90-6. Brigade trains should locate near an airstrip that can handle USAF tactical airlift. They are an obvious target for enemy air attack or artillery, or raids by enemy deep patrols, so adequate air defense and a coordinated area defense plan are necessary. Guards must be placed on all dominating terrain around the area, equipped with ground surveillance radars and STANO devices, and patrols should be employed outside the perimeter.

Supply points may be set up in the brigade trains area to operate distribution points for Class I, III, and V supplies. However, where routes are limited it may be necessary to resupply totally by air from the DISCOM area.

The variations of supplies in demand in the desert are very much the same as for those in temperate climates and are described in Chapter 4. The differences are described below:

Class I. Mess trucks are not practical in this terrain. Food is either eaten cold, or heated on can heaters. Each soldier/marine should carry a one-day supply of emergency rations to be used if the daily resupply does not arrive.

Class II. There is a high demand for footwear. Combat boots may be expected to last approximately two weeks in the harsh rocky terrain.

Class III. Individual vehicle consumption will be greater than normal. Aircraft fuel requirements are greater, but it should be possible for much of their refueling and servicing to take place well to the rear where resupply is relatively easy.

Water continues to carry a high priority. Demand for water is approximately 9 quarts per day, per man, as a minimum, and sometimes considerably more. Troops should carry four canteens of water, and every effort should be made to prestock water in positions or along routes.

First aid at squad arid platoon level is very important as medics will not necessarily y be able to reach individual isolated positions. It is easy to lose casualties in this terrain so a buddy system to keep watch on each individual should be a matter of SOP. Medical evacuation is most often by air. It is a comparatively long distance to the nearest helicopter landing site, so teams of stretcher bearers will be required.

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