fm 31-71 northern operations (jun 1971)

7/30/2019 FM 31-71 Northern Operations (jun 1971)

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CHAPTER 1

GENERAL

Section I. INTRODUCTION

1-1. Purpose and Scope

a. This manual provides doctrinal guidance tocommanders and staffs for operation and adminis-tration of combat, combat support, and combatservice support units in the northern regions ofthe world. The material contained in this manualis directed primarily toward operations below di-vision level. Operations at division level and above

will be essentially the same as those in other areasof the world. It is the forward elements of divi-sions or task forces that must overcome the manysummer and winter problems inherent in north-ern operations. Commanders and staff officers atall levels must understand and appreciate the ef-fects of the northern environment on the opera-tions of these foward units and carefully considerthem when planning each operation. The readershould refer to FM 31-70 and FM 31-72 and toother manuals of the arms and services for fur-ther information concerning northern operations(app A). The contents of this manual are applica-

ble to(1) General war, to include a consideration

of the employment and protection from nuclearmunitions and chemical, biological, and radiologi-cal agents; and operations in nuclear, chemical, orbiological environments.

(2) Limited war.(3) Cold war, to include stability operations

assistance in internal defense and internal devel-opment operations.

b. The provisions of Standardization of Opera-

tions and Logistics (SOLOG) Agreement 23R,Arctic Doctrine are implemented in this manual.

c. Users of this manual are encouraged to sub-mit recommendations to improve its clarity oraccuracy. Comments should be keyed to the spe-cific page, paragraph, and line of text in whichthe change is recommended. Reasons should beprovided for each comment to insure understand-

ing and complete evaluation. Comments should beprepared on DA Form 2028 (RecommendedChanges to Publications) and forwarded direct tothe Commanding General, United States Army,Alaska, APO Seattle 98749. Originators of pro-posed changes which would constitute a signifi-cant modification of approved Army doctrine maysend an information copy, through commandchannels, to the Commanding General, UnitedStates Army Combat Developments Command,Fort Belvoir, Virginia 22060, to facilitate reviewand followup.

1-2. Area of Northern Operations

a. The area of northern operations (fig l-l),for purposes of this manual, is defined as thosenorthern areas of the Northern Hemispherewhich lies north of the temperate zone where en-vironmental conditions require the application ofspecial techniques and equipment that normallyare not required for operations in a more temper-

ate climate. Included in both summer and winteroperations are the considerations of mountain op-erations and inadequate land lines of communica-tions. Although the area of northern operations isgraphically described, the doctrine and techniquesput forth in this manual may be applicable in anyarea of the world that has snow and cold weather.

b. The term northern operations, as applied tothis manual, includes both the Arctic and subarc-tic. About 45 percent of the North American con-tinent and 65 percent of the Eurasian land masslie in these regions.

c. For purposes of this manual, the terms, coldweather operations, operations in the subarctic,arctic operations, operations in the far north, op-erations in northern latitudes, polar operations,and operations on polar ice, will be consideredsynonymous and will be combined under the allencompassing term, northern operations. Thisterm embraces operations in both summer and

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winter and is applicable toEurasia.

1-3. Basic Considerations

North America and

a. The northern environment is a dynamicforce. He who recognizes and understands thisforce can use it; he who disregards or underesti-mates this force is threatened with failure or de-struction. Because of the demanding requirementson the individual solider, leadership must be ofthe highest caliber. Leaders at all levels down tothe squad, must make decisions far surpassing thescope of their usual responsibilities. In the norththe human element is all-important. The effective-ness of equipment is greatly reduced. Specializedtraining and experience are essential. The climatedoes not allow a margin of error for the individ-ual or the organization.

b. The ground mobility of all units is restricted.Movements must be carefully planned and exe-cuted with the knowledge that distance can be asdifficult to overcome as the enemy. Momentum isdifficult to achieve and quickly lost. All availablemeans of transportation must be considered andused to maximum advantage.

c. Because of the stresses imposed by the north-ern environment, maintenance of equipment isdifficult and of great importance.

1-4. Organization

With modifications, the current Army divisions,

and other combat, combat support, and combatservice support units are suited for operations inthe north. The MTOE changes in personnel struc-ture and equipment authorizations are the resultof added emphasis on mobility, maintenance, com-munications, and additional logistical support.Certain items of equipment are eliminated oradded based on their suitability to the terrain, theenvironment, and the concept of operations.

1-5. Command Leadership

Because of severe environmental conditions lead-

ership in the north is highly demanding. Empha-sis is on small unit operations. Command is decen-tralized to insure maximum flexibility for leadersat all levels. Resourcefulness and initiative arerequisites for unit commanders. Forceful and per-sonal leadership is the key to success in the north.Commanders at all echelons must plan and pre-pare their operations in great detail, actively su-pervise, keep themselves and their subordinates

FM 31-71

informed, and maintain close coordination withadjacent and supporting units.

1-6. Tactics

a. Tactical principles for operations in thenorth are the, same as those employed in otherareas. However, because of the environment, em-

phasis may be placed on principles which are lessimportant in areas of milder climate.

b. Mobility is a cardinal principle of operationsin the north. Mobility can only be obtainedthrough proper integration and use of all appro-priate transportation, including aircraft, wheeledand tracked vehicles, water craft, and individualmeans. The fundamental principles and tech-niques of airmobile and riverine operations, pre-scribed in FM 57-35 and FM 31-75, with specialconsiderations discussed in this manual, are appli-cable to combat in northern areas.

c. Operational planning emphasizes the use ofenvelopments to exploit the principle of surprise.The attack may be conducted as an envelopmentto seize objectives from which the enemy positionmay be dominated by fire or from where he maybe attacked from the rear. With the proper use ofairmobility most operations will be in the form ofreconnaissance and security missions with theobjective of finding the enemy and destroying himin place with all available means of firepower.

d. Where predominantly ground forces are em-ployed, movement to contact is conducted under

cover of a highly mobile force. The force shouldcontain aviation, combat support and combatservice support elements, and sufficient fire powerto eliminate minor opposition.

e. In winter operations during the long periodsof darkness, night movement and night operationsshould become the rule rather than the exception.An attack has a better chance of succeeding dur-ing the night because during daylight columns oftroops and equipment are easily located and areextremely vulnerable.

f. Lines of communications are the life blood of

forces in the north. Enemy forces may be de-feated by severing his air and ground lines ofcommunication since the terrain and climate maydeny the availability or use of alternate routes.

g. Lack of adequate ground lines of communica-tions requires more emphasis on the use of air-craft and low ground pressure cross-country vehi-cles for supply, resupply, and troop movement.

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h. Deception is vital in all operations because ofvulnerability of forces in the north brought on byproblems of concealment, slow movement oftroops, and limited land lines of communications.

i. In winter, denial of adequate shelter to aforce can cause casualties as surely as the deliveryof fire power. This fact can work for or against

the field unit.1-7. Logistics

a. The unusual weather and terrain conditionsthat are found in northern areas make problemsof supply, evacuation, transportation, and servicesmore difficult and more time consuming. Time andspace factors vary with the terrain, the climate,and the season. More time must be allowed formovement of supplies and troops because of theenvironment. Distance is measured in time ratherthan space.

b. Commanders must issue their orders early to

allow adequate time for subordinates to move sup-plies and equipment. Logistical support planningis required in great detail, even for small unitoperations. Adequate support must be provided totroops to insure survival and comfort as well ascombat resupply. Plans should include considera-tions for food, fuel, clothing, sleeping gear, ten-tage, mountain gear, winter equipment, repair

parts, and ammunition or nuclear weapons, asappropriate. All means of transportation, to in-clude aircraft, boats, wheeled and tracked vehi-cles, and individual means, must be considered inmovement of supplies and equipment.

c. The capacity of the combat service supportunits to provide adequate logistical support maybe the determining factor in evaluating the feasi-bility of a planned operation. The commandermust be ready to alter the plan when environmen-tal stresses make it impossible for the combatservice support units to provide necessary sup-

port.

Section II. EFFECTS OF ENVIRONMENT ON MILITARY OPERATIONS

1-8. General

In northern areas, the conduct of military opera-tions is greatly affected by considerations foreignto more temperate regions. These considerationsinclude the long hours of daylight (fig 12) anddust of summer, the long nights and the extremecold of winter, and the mud and morass of thetransition periods of spring and autumn. The dis-rupting effects of natural phenomena, the scarc-ity of roads and railroads, the vast distances andisolation (fig 13), and occasionally the lack ofcurrent maps combine to affect adversely but nottotally restrict mobility, fire power, and communi-cations. In spite of these conditions, operationsare feasible through employment of aggressiveleadership, a high state of training, and adequatelogistical support.

1-9. Operating Conditions

a. The most suitable time for ground operations

is from midwinter to early spring before thebreakup period. The snow is settled, givingwell-trained and supported troops an excellent op-portunity for oversnow mobility. During this pe-riod, operations are possible even in a roadlesswilderness. Early winter, after the formation ofice, is also favorable; however, it does not affordwell-trained troops the same oversnow and cross-

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country mobility as midwinter. The winter coldrequires the use of special cold weather clothingand equipment and places a premium on fuel forwarmth. Tracks in the snow, and fog created by aheat source, complicate the camouflage of posi-tions. The blending of terrain features, lack ofnavigational aids, fog and blowing snow all com-bine to make land navigation exceedingly difficult.

High winds and the phenomenon of whiteout caninterfere with aviation operations. High windsalso combine with the cold to make moderatelycold weather extremely uncomfortable. In mid-winter, the environmental factorsextreme coldand snowmay be used to advantage by leaderswith initiative and ingenuity.

b. Limited objective operations are feasible inspring if timed for the period when daytime thawand nighttime freeze leave only a thin layer ofmud on deeply frozen ground, and lake andstream ice is still firm. However, these operations

may be interrupted by sudden breakup periods,causing them either to slow down or stop entirely.

c. From the end of the breakup season throughautumn, operations can be resumed only after theground has dried sufficiently to allow cross-coun-try movement. Men and vehicles, to some degree,regain mobility. When operating in the low areas,the numerous streams and swamps will require


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greatly increased engineer effort and the use ofspecial equipment. The many rivers and streamscan sometimes be used for the movement of troopsand supplies.

d. Poor drainage may cause low lying countryto become isolated from the surrounding terrain.Roads may become flooded. Poorly constructedroads disintegrate. Often, the only means oftransportation is by aircraft and low ground pres-

sure vehicles or watercraft. Attempts to maintainnormal ground mobility are very exhausting totroops and hard on equipment. In brief, otherthan during the period from midwinter until earlyspring, offensive operations which require long-range mobility will be dependent for the mostpart on air movement.

1-10. Weather Phenomena

a. Whiteout. A milky atmospheric phenomenain which the observer appears to be engulfed in auniformly white glow. Neither shadows, horizon,nor clouds are discernible. Sense of depth andorientation is lost. Only very dark nearby objectscan be seen. Whiteouts occur over an unbrokensnow cover and beneath a uniformly overcast sky.With the aid of the snow blink effect, the lightfrom the sky is about equal to that of the snowsurface. Blowing snow can cause the same effect.The whiteout phenomena are experienced in theair as well as on the ground.

b. Greyout. Greyout is a phenomenon whichoccurs over a snow covered surface during twi-

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light conditions or when the sun is close to thehorizon. There is an overall greyness to the sur-roundings, and when the sky is overcast withdense cloud there is an absence of shadows, result-ing in a loss of depth perception which in-creases the hazard in landing an aircraft, drivinga vehicle along a road, skiing or even when walk-ing, with the effect greatest when a person is fa-tigued. Under certain greyout conditions, it hasbeen found almost impossible when driving to dis-tinguish the road from the ditch or from thesnowbanks along the roadside. The phenomenon issimilar to whiteout except that the horizon is dis-

tinguishable under greyout conditions and notdistinguishable during a whiteout.

c. Ice Fog. The phenomenon of ice-particle fogsis a very common occurrence around inhabitedareas during cold winter weather. They are foundmost of the time when temperatures drop below-35F. Their origin, in marked contrast to thatof ordinary super-cooled fogs, lies in the copiouslocal production of water vapor by human activi-ties, coupled with an inability of the stagnant airat such low temperature to hold the water vapor.Such sources of water vapor may include the ex-haust from vehicles and aircraft, the vents of

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steam from permanent type heating systems, the when firing. Ice fog obscures the gunners visionair ventilated from humid rooms, and the stove along the line of fire and may disclose the locationpipe from space heaters. In the field, such a fog of weapons, vehicles, and troops. During darknessmay appear over a body of troops, bivouac areas, ice fog limits or negates the effectiveness of nightmotor parks, airfields, convoys, and gun positions vision devices.

Section III. MOBILITY

1-11. General

a. Ground mobility is affected by inadequatetransportation nets. During the winter, low tem-peratures, snow and ice, and the difficulties ofconstructing roads and trails hinder movement.During the breakup season, ice is weakened onlakes and streams, and existing roads may becomealmost impassable. Extensive overland movementis difficult during the summer because the under-lying permafrost prevents effective drainage andextensive swampy areas result.

b. Movement by helicopter or by fixed wing air-craft equipped with conventional landing gear,skis, amphibious landing gear, or flotation kitsoffers an effective means of mobility in the unde-veloped regions of the north.

1-12. Effects of Climate

a. Winter Condition.(1) Snow affects mobility of ground troops in

a number of ways. Heavy snow cover impedesmovement, either cross-country or on roads. Snowcover also blankets many terrain features, hiding

obstacles to movement such as brush, stumps,rocks, ditches, small streams, fallen trees, minefields, and other manmade obstacles. Snow coveracts as a thermal insulator which retards thefreezing or thawing of underlying ground. Whensnow melts, it saturates the ground and oftenmakes it impassable. Snow or ice on roads, undercertain conditions, makes driving difficult anddangerous. On roads and airfields, snow increasesmaintenance requirements since it requires re-moval or compaction. Traction on compacted snowis generally better during extreme cold weather.

(2) The effect of snow cover on mobility var-ies greatly with both depth and physical charac-teristics of the snow at any particular time andlocation. The factors stated in this subparagraphare generalizations only. Conventional wheeled ve-hicles or men on foot cannot travel satisfactorilyover flat terrain or roads when the depth of uncom-pacted snow exceeds 30 cm (12) in depth. Mosttracked vehicles are slowed by a snow depth of 60to 75 cm (24 to 29). Low-ground-pressure

tracked vehicles can generally operate effectivelyin deep snow. However, snow of more than 76 cm(29) depth, especially when granular or pow-dery, can stop movement except for special over-snow vehicles. The physical strength of snow gen-erally increases with reduction of temperatures.Frequently, movement across a snow covered areaimpassable during the day may become passableduring the night after a sharp drop in tempera-tures. Because the depth and characteristics ofsnow cover can vary greatly within short distancesand short spaces of time, up-to-date reconnais-

sance of snow conditions in the operational area isessential to the planning of overland movement.

(3) Individual oversnow mobility is enhancedby the use of skis or snowshoes.

(a) Skis afford greater speed in moving,particularly over prepared trails and usually re-quire less physical effort. Condition of snow(depth, trail broken, etc.) will affect this speed.Troops mounted on skis and towed behind vehicles(skijoring) are an effective means for rapidcross-country movement where trafficability per-mits. Troops moving by this means will arrive at

their destination less fatigued and in better condi-tion to conduct effective operations. Three to fourweeks are normally required for troops to becomeadequate military skiers. However, this trainingtime is only an approximation and dependslargely on the adaptability of the troops. Somepersonnel will become proficient in one or twoweeks while others, because of lack of coordina-tion, etc., will require additional effort.

(b) Snowshoes, though slower than skis,require less training. Troops in good physical con-dition can develop adequate proficiency in a fewhours. Snowshoe movement is more practical inconfined areas, such as assembly areas, fieldtrains, mortar and artillery positions.

(c) As a general rule units that move onfoot should be trained to become proficient onboth skis and snowshoes.

b. Summer Conditions. The northern regions insummer are characterized by an abundance ofopen lakes, streams; and swamps which impede

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movement. Waterways may be used for militarymovement if equipment or improvised rafts areavailable. With detailed current reconnaissance,streams, creeks, and graveled river beds may beused as routes for tracked vehicles through mus-keg areas.

c. Seasona1 Changes.

(1) During the spring breakup when riverice begins to thaw, the surrounding country maybe flooded and impassable. The breakup is charac-terized by large ice jams. During this period vehi-cles should carry reduced loads. Traffic should bepermitted only at night when temperatures arebelow freezing. This will allow engineers time toperform necessary maintenance without interrup-tion during the day. When nights become so warmthat the roads will no longer freeze, heavy trafficmay turn unpaved roads into morasses. At timesall movement on roads maybe stopped because ofdeep mud.

(2) In some areas of the north, fall rainscomplicate military movement. Unpaved roads arethawed during the summer, and the fall rainscreate deep mud. Ruts made in the mud duringthe day will freeze on cold nights and make move-ment with vehicles difficult. Frozen ruts tear tiresand break wheels and axles. Vehicles may breakthrough the thinly frozen crust and may bogdown. Under these conditions, vehicles should notfollow in the same tracks of the preceding vehicle.

(3) As the freezeup progresses and theground becomes firm enough for tanks and other

vehicles, cross-country movement is facilitated.However, great care must be exercised whentanks and heavy equipment, such as bulldozers,are being used on streams, lakes, or muskeg.These heavy vehicles may break through thinlyfrozen ice or ground and sink into the mud orwater. Once vehicles become mired, recovery isextremely difficult and time-consuming (see TM5-349).

(4) Another hazard to cross-country move-ment is warm water springs, especially when cov-ered with snow. Many of these springs do notfreeze and cause some streams to have little or no

ice and some lakes to have only thin ice. Theirpresence in muskeg areas can cause weak spots inotherwise trafficable terrain.

1-13. Terrain

a. Various types of terrain present differentproblems. Obstacles to summer movement includeclose tree spacing and fallen trees in forested

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areas, rocky hummocks, boulders, bogs, riverslakes, and swamps. During winter, deep in snowforested areas becomes an obstacle to movement.

b. Nonforested areas include the tundra. Dur-ing summer, large areas of tundra resemble greatplains. It is covered with a thick layer of hum-mocky moss interspersed with extensive marshes

similar to those of temperate areas but usuallynot so deep because of the high permafrost table.The depth to the permafrost level will usuallyvary from 15 to 60 cm ( 6 to 24). Tundra soilsare extremely moist. Cross-country tracked vehic-ular traffic is possible; soft, waterlogged soils,however, afford little or no wheel traction. Traff-icability of the frozen tundra surface with itslight snow mantle is much better in winter thanin any other season.

c. The most serious obstacle to movement overglaciers and ice cap areas is crevasses. Special

equipment is available and must be used whentraversing glaciers and ice cap areas. Trailsshould be selected and marked by the trailbreak-ing party when moving over any area that maycontain crevasses. With the coming of low temper-atures in winter, ice cap surfaces become hardand wind swept. Newly fallen snow is blown intosnow ridges which may be obstacles to movement.Wind blown compacted snow may become so hardthat it will support troops on foot. Mechanizedtransportation is possible on this surface if snowridges do not interfere. In many places, ski-equipped aircraft may land and take off with

safety.

1-14. Vehicular Mobility

If a means to move by air is not available or ifweather precludes airmobility, the operation mayhave to be mounted with vehicles, either wheeledor tracked. If such is the case, selection and prep-aration of a route for vehicular movement re-quires special techniques.

a. A thorough map and terrain analysis is re-quired to determine a number of possible routesthrough an area. Routes should be selected thattake advantage of natural cover, gain concealmentfrom air observation and avoid steep slopes, ab-rupt ravines, unfrozen swamps, open streams, andother obstacles. In winter, low terrain usuallyprovides the best routes; in summer, routes nor-mally should follow ridgelines where solid groundis to be found.

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map study and/or aerial reconnaissance are thenchecked by a helicopter-borne or foot reconnais-sance team. If possible, the helicopter-borne partyshould land and select a route over the most diffi-cult terrain obstacles by ground reconnaissance.In selecting routes through heavily forested areas,a reconnaissance is made for lanes which may bewidened. Edges of forest are often suitable.

Routes in forests should be selected where treesare widely spaced and, if possible, in sandy soil.This will make it easier for heavy equipment tobreak trail and clear trees.

c. The advance guard of the column is providedthe recommended route to be used by a helicop-ter-supported reconnaissance team. The advanceguard then moves, breaking a route which is sat-isfactory for heavier tracked vehicles. Vehiclesthat may be used to break trail are tanks orcombat vehicle mounted bulldozers, and in somecases, armored personnel carriers.

d. As soon as possible, this route should be im-proved by bulldozers pushing off broken timberand, in winter, the excess snow. The road shouldbe improved to carry all of the tracked equipmentin the brigade trains and be at least one lane widewith sufficient turnouts to accommodate some re-turning traffic. At times, trail breaking vehiclesmay have to deviate slightly from the route se-lected by the reconnaissance unit to avoid openwater and excessive slopes. However, the mainsupply route (MSR) capable of carrying alltracked vehicles of the unit, normally will followthe general route selected by the reconnaissanceunit.

1-15. Time Lag

a. In addition to the increased amount of timeconsumed in actual movement, allowance must bemade for other time-consuming tasks not presentin normal operations. These time-consuming tasksnormally increase the time between issuance of amarch order and the start of its execution. Everyeffort should be made to compensate for this timelag by early issuance of warning orders and frag-mentary orders.

b. Upon receipt of the march order, men mustadjust their clothing and equipment. Frequently,this will save unnecessary halts for adjustment ofclothing, rucksacks, skis, or sled loads. The lead-ers must insure that the men do not overdress,thus increasing the possibility of overheating andexhaustion.

c. The unit leader must assure himself thatevery piece of necessary clothing and equipmentis present and in serviceable condition. Althoughthis becomes routine, it is still time consuming.

d. Movement will be slowed while operating inlow temperatures because heated shelters (tentswith stoves and fuel) usually are transported withor by the troops. Time is consumed in strikingshelters and loading equipment. Similarly, whenthe march is completed, camp sites must be pre-pared, tents erected, and stoves put into opera-tion. During the cold season, shelters are notstruck until the last possible moment prior to be-ginning the march, so as to provide heat and shel-ter as long as possible. Although considerabletime is consumed in pitching and striking tents,experience has taught that it is still less time con-suming to utilize this transportable type shelterthan to construct improvised shelters. Under cer-tain conditions patrols and other small units canutilize snow caves and snow houses for shelter.However, this means of shelter should be revertedto only as a last resort or when other shelter isunavailable.

e. If vehicles are to be included in the marchcolumn in extreme cold, sufficient time should beallowed for starting and warming their engines.Engine starting and warmup procedures are pre-scribed in TM 9-207.

f. Trailbreaking detachments, which move at aslower rate than the reminder of the march unit,should be started soon enough to avoid delayingthe main body. To reduce fatigue and to increasethe rate of movement, trailbreaking detachmentsand individual members should be rotated as oftenas necessary.


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CHAPTER 2

OPERATIONS

Section I.

2-1. Concept

a. Extended areas of responsibility, reductionin troop density, and battle area isolation, plusdifficulties in command and control, require theuse of mission type orders that give maximumlatitude to subordinate commanders. Northern op-erations require that tactical commanders begiven every possible opportunity to exploit localsituations and take the initiative when the oppor-tunity is presented.

b. Planning of any scope must emphasize thelogistical impact of any tactical scheme on theoverall support problem. The lack of roads andshelter, plus climatic severity and other environ-mental difficulties, require that logistical plans beflexible and adaptable enough to permit adjust-ment of supply means without endangering theoverall effort. Restrictions imposed by extremes ofclimate and terrain constitute the major changefrom operations in temperate areas. These restric-tions may, unless proper provisions are made,constitute major obstacles to the successfulconduct of the operation. Mobility is a prerequi-site to success. It can be achieved only throughcareful planning, training, and the use of special-ized equipment.

2-2. Special Factors

The following special factors will influence opera-tional planning:

a. Low Population Density. Settlements, sup-

plies, quartering facilities, and lines of communi-cation are limited. Their control or destructionbecomes highly important.

b. Roads and Railroads. Roads and railroadsmay be limited and those that exist usually arevulnerable to enemy action. In addition, climaticconditions may greatly affect their use.

c. Lakes and Waterways. Lakes and waterwaysare prevalent and may either aid or hinder the

PLANNING

operation depending upon climatic conditions.With sufficient ice thickness, they are easilycrossed and may be used as natural routes of com-munication or airstrips. In some instances, driftedand hard packed snow makes landing on ice diffi-cult, requiring further preparation of the airstrip.In the summer, waterways may either be majorbarriers or lines of communications. Many of the

streams are glacier-fed and carry great volumesof water in the summer. The amount of water inglacier-fed streams may vary considerably duringany 24-hour period, particularly near its sourceand when daytime temperatures are warm andnighttime temperatures are near freezing. Carefulreconnaissance is required to determine the dailychanges in the volume of water throughout theday. Location of the main channel often changesfrom year to year.

d. Mapping. Occasionally, maps maybe unrelia-ble or even nonexistent. Therefore, the require-

ment for timely aerial photographs must be uti-lized as a source of terrain information. Withproper preplanning, suitable aerial photographycan be made and converted into a photomap bysupporting engineer topographic units. Unlessproperly laid out, annotated and referenced toknown survey points, the aerial photograph willnot provide necessary map-like accuracies fornavigation and employment of indirect fire weap-ons.

e. Navigation. Difficulty of land navigation isincreased by lack of landmarks, large forested

areas, periods of reduced visibility, difficulty ofcross-country movement, and by large magneticdeclinations.

f. Weather. Weather is an important factor tobe considered in the estimate of the situation andmay dictate a course of action. As an example, theattacker or defender in a snow storm with thewind at his back has a marked advantage.

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g. Forestedcealement andambushes andcomparatively

Areas. Forested areas offer con-present excellent opportunities forhit-and-run tactics. They providegood protection against wind and

snow storms but present a serious obstacle tocross-country mobility. In the summer, forestsburn easily, and fires may become a major prob-lem. Units in forested areas are highly vulnerableto the blast effect from nuclear weapons.

h. Snow Cover. Snow enhances the movement oftroops suitably equipped and trained, but reducesthe mobility of troops lacking proper equipmentand training.

i. Ice Cover. Freezing of rivers, lakes, andswamps aids movement and operations.

j. Extreme Cold. The effects of extreme coldmust be considered in planning operations. Thepropser use and care of clothing and equipmentwill largely overcome most difficulties; however,extremely low temperatures combined with windcan be very hazardous to personnel operating out-side. The effect of these two elements occurringtogether is called windchill, which greatly in-creases the speed at which exposed flesh willfreeze and the length of time personnel can operatein the open (fig 2-1). The human body is contin-ually producing or losing heat. Wind increases theloss of heat by reducing the thin layer of warmair next to the skin. This loss increases as thespeed of wind increases Any movement of air pastthe body has the same cooling effect as wind. This

may be produced by walking, running, skiing, orriding in an open vehicle.

k. Sudden Changes in Weather. These changesinclude extreme temperature changes, snowstorms, strong winds, and dense fog. Changesmay be sudden and must be anticipated. Everyadvantage must be taken of favorable conditionsof even short duration. The commander who hasthe ability to predict, with accuracy, the suddenchanges in the weather will have a distinct advan-tage over the enemy forces. The importance oflocal weather prediction capability cannot be ov-

eremphasized.l. Daylight and Darkness. The long night of the

winter must not be considered a bar to operations.For example, movement, camp building andbreaking, scouting, and patrolling must be consid-ered normal night activities. The proper utiliza-tion of the available daylight hours assumesmajor importance in planning.

m. Seasonal Transition. The periods of seasonal

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transition must be carefully considered. Climaticchanges become more abrupt and the appearanceof terrain features changes rapidly. A frozenriver may one day present little problem and thenext day be a major obstacle.

n. Atmospheric Disturbances. Extended opera-ting distances and atmospheric distrubances make

military communications difficult.o. Delayed Personnel Responses. The extreme

environmental problems encountered by personnelrequire that delay and time lag be considered inall planning.

2-3. Fire Support

a. General. Fire support planning for northernoperations basically is no different than that re-quired for more temperate regions. However,limited ground mobility of artillery weapons, andammunition supply, and increased time of opera-tion increase the requirements for Army aviationaerial rocket artillery and aerial fire support, andtactical air support.

b. Tactical Air. The importance of tactical airsupport is increased greatly in northern opera-tions, primarily because of the remoteness ofnorthern areas and the lack of suitable routes ofsupply and communications, and the resulting rel-ative unavailability of normal fire support ele-ments.

c. Fighter-Bomber Support.

(1) Tactical air strikes by fighter-bombersmay often be used to supplement fire support nor-mally obtained from organic support means. Inmountainous terrain or in glacier operations, airstrikes may be the only fire support means availa-ble other than mortars or recoilless weapons.

(2) Movement of forward air controllers(FAC) to points where they can control airstrikes is a problem in northern operations. Lightaircraft, particularly helicopters, are the bestmeans for placing the FAC in a position to see thetarget and direct the fighter aircraft. Ground

transportation for the FAC is inadequate as hecannot move rapidly from the area of one airstrike to the area of another.

2-4. Additional Considerations

a. Lack of large population densities and in-dustrial complexes in the north have direct impacton unconventional warfare activities. Low sub-sistence levels, lack of shelter, and primitive com-

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munications also are of importance in designatingunconventional warfare operational areas. Theimpact of terrain, extended frontage, extremeweather conditions, and extended periods of dark-ness on the logistical operations of regular forcesis highly favorable to guerrilla operations. Ex-tended lines of communication restrict groundmovement to a few routes which are highly vul-nerable to such operations.

b. Psychological warfare opportunities inherentin the environmental extremes, isolation, and per-sonal discomfort present in northern operationsare exploitable. Winterization of loudspeakerequipment and printing presses is a requirement.Low troop density, difficulty in positive identifica-tions, and relatively limited movement of troopsin tactical localities make accuracy in leaflet dis-semination and radio broadcasting critical.Enemy psychological warfare operations may be

expected to utilize all available propaganda media,(radio, printed matter, loudspeaker, rumor, etc.)to emphasize discomfitures due to the environ-ment in attempting to reduce the morale of ourforces.

c. The strategic location of certain remotenorthern areas and their characteristically severe

climate, low population density, possible govern-mental neglect or disinterest resulting in antipa-thy, ignorance, or restlessness of the inhabitants,provides a target or breeding ground for subver-sion. Although generally not regarded likely areasfor insurgency, control of northern areas withinthe context of a larger plan, may be a cold warobjective. If insurgency occurs, internal defenseoperations must take place to maintain control ofthose areas for friendly forces exploitation oftheir strategic value (FM 31-16 and FM 31-22).

Section II. ORGANIZATION

2-5. Forces

a. Infantry, Airmobile, and Airborne Divisions.(1) The combined arms brigade task force is

the basic building block for the infantry divisionin northern operations. The division can conductlimited airmobile operations with organic Armyaviation but should be trained to conduct totalairmobile operations by the attachment of nonor-

ganic Army aviation.(2) The airmobile division is employed infurtherance of the ground combat effort under theguidance and doctrine contained in FM 57-35 andchapter 6 of this manual.

(3) Airborne divisions conduct conventionalairborne operations in furtherance of the groundcombat effort. Techniques are modified as indi-cated in chapter 6 of this manual.

b. Armored and Mechanized Divisions. Theclosely integrated combined task force is the basicbuilding block for armored and mechanized divi-sion operations. These task forces as an optimumare highly mobile and include Army aviation, en-gineer, and signal units. They are supported logis-

tically by a mobile direct support element. Thetask forces must be capable of conducting inde-pendent operations at extended distances fromhigher headquarters, adjacent units, and logis-tical bases.

2-6. Command and Controla. Mission type orders are the rule.

b. Command posts and control facilities aresometimes mechanized. Vehicles and shelters re-quire either self-contained or associated heatingand lighting.

c. The use of highly mobile signal equipmentwith a cross-country or airborne/airmobile capa-bility is an absolute requirement for the taskforce in northern operations. Relay capabilitiesare frequently required both within the task forceand between the task force and higher headquar-ters.

d. Reduced ground visibility, lack of nega-tional aids, and extended distance require the useof Army aviation as a means of command recon-naissance, liaison, and communications relay.

Section III. COMBAT INTELLIGENCE, PATROLLING, COUNTERINTELLIGENCE AND SECURITY

2-7. Combat Intelligence swers to at least two important questions are nec-

a. In addition to the essential elements of infor- essary to successful winter operations in the

mation required for other types of operations, an- north. The questions are

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(1) What is the enemy capability for movingcross-country?

(2) What is the enemy capability for livingand fighting for prolonged periods in extremecold?

b. A checklist to assist in determining the an-swers to these two questions might include

(1) Is the enemy equipped with skis orsnowshoes?

(2) What is the enemy status of training intheir use?

(3) Does the enemy have oversnow orthrough the snow vehicles? What kind?

(4) Does the enemy have any snow removalequipment? What kind?

(5) What types of artillery are being used bythe enemy (SP or towed)?

(6) Are guns ski-equipped?(7) Is the enemy using sleds or some other

type of oversnow transport to move unitequipment?

(8) Is the enemy using heated shelters? Whatkind?

(9) Can shelters be moved cross-countrywithout vehicles?

(10) Is the enemy using improvised shelters?(11) What type of winter clothing is used by

the enemy? What protection will it afford?(12) What kind of weapons does the enemy

have? Are they effective in extreme cold? What is

their effect in deep snow? Can their heavy weap-ons follow infantry units in cross-countrymovements?

(13) What kind of aircraft does he use intransport or fire support?

(14) What logistical support capability doesthe enemy have?

(15) What is the enemys airmobilecapability?

c. For summer operations, units should deter-mine if the enemy has cross-country vehiclescapable of negotiating muskeg or swampy ter-

rain: if he has boats is he using them and forwhat purposes; and if he has bridging equipmentand units.

d. Personnel must be aware of intelligence indi-cators that are present in a cold weather andnorthern environment. These indicators can bebroken down into two categoriesthose that indi-cate the presence of a hostile force in the area,and those that indicate the size of the force. If

these indicators are not recognized by the intell-igence staff officer, the tactical commander will notbe given a complete intelligence estimate on whichto base his decisions.

(1) Examples of cold weather indicators thatmay indicate the presence of or passage of a hos-tile forces are

(a) Signs of former bivouac areas:1. Packed snow.2. Emergency shelters.3. Remains of fires.4. Trail networks.5. Trash left in the area.6. Freshly cut wood.

(b) Tracks in the snow that were made by:1. Men on skis or snowshoes.2. Tracked vehicles.3. Helicopters.4. Aircraft using skis.

5. Air cushion vehicles.6. Sleds.7. Wheeled vehicles.

(c) Improvement of winter trails.(d) Presence of winter landing fields.(e) Presence of ice bridges.(f) Ice fog.(g) Smoke.(h) Manmade or mechanical sounds.(i) Hot spots on IR sensors.

(2) Examples of cold weather indication that

may indicate the size of a hostile force in an areaa re(a) Site and configuration of bivouac

areas.(b) Size and number of shelters or tents

present in a bivouac area.

(c) Number of hot spots present on IRsensors.

(d) The number of trails present within agiven area.

e. Detailed knowledge of the terrain and clima-tology of the area of operations is essential. The

location and condition of the existing road net andrailroads, if any, must be determined. Informa-tion regarding soil trafficability, vegetation, waterroutes and expected ice thickness, snow condi-tions, wind velocity and direction, and averagesnow depth should be available to the commander.The general features of the terrain from the view-point of cross-county movement should also beknown by the commander. For summer opera-

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tions, it will be necessary to determine waterroutes suitable for transpotation and dry groundroutes in barren lands.

f. The increased effect of weather on militaryoperations in northern areas makes it mandatorythat continual and accurate weather forecastlerapidly disseminated to the lowest level.

g. Collection agencies are essentially the sameas for temperate zone operations although theirmethods of operation may be different. Increasedemphasis must be placed on effective use of airreconnaissance by both Army aircraft and thesupporting Air Force units. During seasons whenwaterways are open, boat patrols are useful ingathering information.

h. It is especially important during the plan-ning phase of northern operations to secure de-tailed information of the operational areas from

strategic intelligence agencies. Every effort shouldbe made to procure basic airphoto coverage of thearea for each season. Streams, lakes, swamps, andthe general conformations of the ground mayshow clearly on aerial photographs taken duringwarm months but may be extremely difficult todistinguish on aerial photography taken when wa-terways are frozen and the ground is covered withsnow. The enemys need to rely heavily on radioalso provides a valuable and often times easilyaccessible source of intelligence. Support Army Se-curity Agency elements should be tasked to assistin providing input to the EEI in the form of sig-

nal intelligence.i. After operations are initiated, some collection

means, such as long range patrols, lend them-selves to more than usual exploitation in obtain-ing information deep in enemy territory. Becauseof the unusually great operating distances, thesepatrols can often pass undetected through flankand frontal areas. Indigenous personnel assumeincreased importance as a source of information.Use of special forces working with the inhabi-tants in the area of operations prior to full scaleoperation will enhance the information-gathering

capability of the ground forces.j. Aerial surveillance by the OVl Mohawk can

be advantageously employed by the use of its var-ious sensors. The infrared (IR) detectors can beused to locate enemy or friendly base camps andisolated groups of men during the long hours ofdarkness in the winter as well as during daylighthours. The side-looking airborne radar (SLAR)capability provides for detection and location of

moving targets on the ground. This information(location and size of element) provides the fieldcommander with vital intelligence for immediateand future operations. Data link of IR and SLARprovides instant readout of information at thecommand post location. The day and night photocapability can be used to identify friendly and

enemy personnel, equipment, and base camps. Thepanoramic, vertical, and oblique photos can pro-vide aid for advance planning or provide currentindigence data in a static situation.

k. Unattended ground sensors can be employedduring the summer season in the same manner asthey are used in other areas of the world. Theiruse during the winter may be limited because ofbattery failure caused by extreme cold.

2-8. Patrolling

a. Patrolling to provide information of the

enemy and to provide security increases in impor-tance since combat units will seldom have anyclose neighboring units.

b. Reconnaissance and combat patrols may op-erate behind enemy positions for extended peri-ods, depending upon climatic conditions and thecapacity to provide support. Subject to equipmentissued and weather conditions, such patrols can beself-sustaining for periods of from 3 to 5 dayswithout resupply except for ammunition that maybecome expended. Ideally, personnel employed onthese patrols should be specially trained, including

mountain and glacier operation. Whenever possi-ble, qualified skiers should be used in order toincrease the cross-country mobility of patrols.Provision should be made for such patrols tocarry, in addition to weapons, communications,etc., minimum equipment for survival includingtent, stove, and fuel. Prearranged supply dropsmay be used for replenishment of supplies.

c. The most economical way to move long rangepatrols into enemy territory is by aircraft. Attimes, it may be feasible to pick up patrols fromenemy rear areas by aircraft. During winter,

escort patrols should be sent with long-rangeground patrols to insure that the long range pa-trols get through enemy lines, to carry additionalrations for later use by the long range patrols,and make deceptive tracks on both sides of theroute of the long range patrol.

d. Air cavalry units with attack helicopters areideally suited for security and reconnaissance innorthern operations.

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e. In long-range patrolling communications area prime consideration. Normally, radio is theprincipal means of communication; however, be-cause of extended distances and difficulty in radiotransmissions in northern areas, aerial relays ormessage pick up and drop techniques may have tobe employed.

2-9. Counterintelligencea. Camouflage.

(1) Camouflage during the winter is exceed-ingly difficult. Reliance should be placed on decep-tion techniques. Commanders must place specialemphasis on camouflage and deception techniques.

(2) Summer camouflage techniques do notdiffer from those applicable in temperate zones.

b. Deception. Deception has an important rolein northern warfare. False ski or snowshoes trailsare made to mislead the enemy as to the size of

the force, direction of movement, and scope ofactivity. Establish rules for track discipline insnow such as; using single file to conceal troopstrength where possible and; restricting the blaz-ing of new trails. Restrict the use of individualwarming fires. Open camp fires can be started indry tree stumps in many locations to deceive theenemy as to size and location of forces. Dummygun positions can be constructed from materialsat hand. Sound and flash simulators should beused in these positions to give them a semblance ofreality. If dummy rubber vehicles and weapons are

FM 31-71

not available, snow and logs can be used as substi-tute materials. All deceptive measures must bewell planned and carefully executed to give themevery appearance of reality. Electronic deceptionis equally important, as the enemy can be ex-pected to gain intelligence by monitoring our nets,in locating our positions by direction finding andemploying SLAR and IR devices to detect our lo-cation and movement. The use of manipulativeelectronic deception, in coordination with tacticalcover and deception, is essential in concealing thelocation of major headquarters and operating ele-ments.

c. Concealment.(1) Excellent concealment for troop move-

ments is afforded by darkness, fog, or fallingsnow. In forests, clearings are avoided, and troopsand vehicles leaving roads should do so only inplaces where the forest is near the road.

(2) In bivouac areas and supply points maxi-mum use should be made of dispersion and vege-tation for concealment.

2-10. Security

Tactical security measures employed in normaloperations remain essentially the same in north-ern operations. Because of the long periods ofwinter darkness and the tendency for sound totravel great distances in cold air, light and noisediscipline deserve special security consideration.

Section IV. OFFENSIVE OPERATIONS

2-11. General

a. Offensive operations are directed toward thedestruction of the enemy in the least possibletime. Ideally, the objective in cold weather opera-tions is not to pit rifleman against rifleman, butrather to destroy the enemy in place by firepower.Actions will be sudden, violent, and decisive. Anoperation which is permitted to lag may result ina stalemate or may offer an opportunity for theenemy to seize the offensive. Both forces retain

freedom of maneuver limited only by their abilityto cope with the climatic and terrain conditions.Due to large operational areas, flanks and rearareas are sometimes lightly defended and presentexcellent opportunities for the conduct of uncon-venitonal warfare, for envelopment, or under fa-vorable conditions, for turning movement.

b. Existing lines of communication must be con-trolled to assure success in northern operations.

Severe winter weather hastens enemy destructionafter supply lines are cut. Breaches in enemy linesof communication should be made in the vicinityof dominating terrain if retention of the area isrequired. During summer, such objectives shouldbe selected where the lines of communicationcross a river or pass between two existing naturalobstacles.

c. Effective utilization of weather conditions in-crease opportunities for surprise attacks. This in-cludes the exploitation of falling snow, blizzards,fogs, low cloud cover, and natural night illumina-tion. Imaginative use of what appear to beweather obstacles may turn them into major ad-vantages. However, conducting offensive opera-tions during severe weather conditions will re-strict the use of aviation support and increasecontrol and reconnaissance problems.

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d. The assault should reconducted at night orduring periods of low visibility. Surprise is animportant factor, and the opportunities forachieving surpirse are numerous. It may be pre-ferable to deliver the assault without field artil-lery preparation fires.

e. A period of slow movement may occur be-

tween the cessation of field artillery fire on theenemy forward positions and the arrival of theinfantry on the objective. This period of slowmovement caused by weather or terrain condi-tions must reconsidered in planning fire supportof the assault. However, when weather, terrain,and lack of effective enemy resistance permits,mechanized infantry may remain in their carriersand make a mounted assault to capitalize on shockeffect and reduce the time lag associated with adismounted assault through snow and under-brush.

f. After seizing an objective, immediate atten-tion must be given to consolidation of the objec-tive. The assaulting troops may be fatigued andoverheated from the exertion of the attack. Provi-sions must be made to prevent them from becom-ing cold casualties.

g. Army aviation can and must be effectivelyintegrated into offensive operations, and airmobileoperations should be considered normal ratherthan special in the northern areas. Verticalenvelopment, diversionary attacks, and rapiddisplacement of supporting weapons and re-serves are within the offensive capabilities of anairmobile force. Low troop density throughout thebattle area plus flexibility in route selectionreduce the hazards of enemy operations andcounter action against movement.

h. During summer months riverine operationsmay be conducted in areas where extensive inlandwaterways exist, using craft adapted to the north-ern rivers.

2-12. Main Attack

a. The opportunity for maneuver is usually pres-

ent in northern operations. Main attacks usuallyare directed against the flanks or rear areas whilesupporting attacks are directed against the enemyfront to hold him in position. An additional forcemay be employed to bypass the enemy positionand cut enemy routes of reinforcement or with-drawal.

b. The most mobile troops are used to breachthe enemy lines of communication.

2-13. Control Measures

Axes of advance normally are used to control for-ward movement during offensive operations.Boundaries forming a zone of action, maybe usedif terrain permits designating discernible bound-aries. In barren, flat terrain, an azimuth may beused to indicate the direction of attack. Intermedi-

ate objectives and phase lines are assigned as nec-essary to control the attack and seize key terrain.

2-14. Coordination

Coordination is extremely important in northernoperations. At times, the distance between twoenveloping forces may become so great that mes-sages must be relayed. The radio relay capabilityof Army aircraft permits significant extension ofthe range of ground tactical radio equipment.

2-15. Attack of an Organized Position

a. Commanders inform their staff officers asearly as possible of all aspects concerning theconcept for conducting the attack, so that anattack order can be formulated as far in advanceas possible. This applies in particular to the logis-tical officer whose arrangements for logistical sup-port are most likely to require additional time innorthern operations.

b. Reconnaissance is initiated early on a widefront with missions of determining enemy loca-tions and reconnoitering routes and terrain, in-cluding terrain in enemy hands.

c. Harassment of the enemy is started simulta-neously with reconnaissance and is executed bypatrols, limited to objective attacks, and interdic-tion by aircraft and field artillery.

d. Prepared fires of supporting field artilleryand mortars are closely coordinated. Forward ob-server parties are included in Infantry recon-naissance patrols and in combat patrols. Prepara-tion of firing positions for supporting weapons isbegun early as it is likely to be time consuming.

e. Engineer reconnaissance troops should be in-

cluded in infantry reconnaissance patrols. Bridg-ing equipment and materials are moved well for-ward to be ready for use when needed.

f. The communication plan is made in detailand must provide measures for overcoming diffi-culties peculiar to northern operations and thenorthern environment.

g. Supply reserves are kept mobile when possi-

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ble. It may be necessary to establish distributingpoints in forward areas.

h. Aerial photos of enemy positions, terrain androutes thereto should be taken when possible priorto the attack.

2-16. Preparation for the Attack

a. When reconnaissance is completed and otherpreliminary measures taken for the attack, trailsare opened to assembly areas. If the distance isnot too great, these trails are not opened until theday before troops plan to move. Wire communica-tions, when used, are laid simultaneously withbreaking of trails.

b. Movement to assembly areas is executed thenight before the attack unless conditions of lowvisibility deny enemy daytime observation. Guidesmust be provided.

2-17. Movement to Line of Departure

A halt is made in the assembly areas only longenough to feed and prepare troops for the attack.Vehicles are dispersed and artillery moved to pre-pared positions and camouflaged or concealed.Troops remain in the assembly area for the mini-mum length of time necessary to prepare for theattack. Supporting weapons are moved to selectedfiring positions.

2-18. Conduct of the Attack

a. The attack may be conducted by the infantryon foot, skis, and snowshoes or transported bytanks or personnel carriers or helicopters. Tech-niques of conducting the attack are as in normaloperations, except when troops are using skis orsnowshoes.

b. When the attack is conducted on skis orsnowshoes, the attack formation should facilitateuse of trails broken by the lead elements of theattacking force. Every attempt is made to get asclose as possible to the enemy before deliveringassault fire. Whenever possible, the attack on

Section V.

2-21. General

a. The defensive is assumed for the same

skis

FM 31-71

or snowshoes should be conducted downslope.Troops do not disperse or halt to fire until reach-ing the assault position or enemy fire becomeseffective. Final coordination lines should generallybe closer to the enemy during winter than duringsummer especially if the assault is made on footthrough snow. The decision as to whether the as-

sault is to be conducted on skis, snowshoes, orfoot must be made by the commander based uponexisting conditions. If skis or snowshoes are re-moved in the attack they should be brought for-ward during reorganization.

c. In continuing the attack, special efforts aredirected toward rapid displacement of close-sup-port weapons using sleds or vehicles. Supplyroutes are prepared as far forward as possible tofacilitate unit distribution.

d. The relief of committed units is executed asunder normal conditions with consideration being

given to rapid relief of assault elements to bringthem back to warm shelter. Warming tents, ifneeded, are moved to the closest available conceal-ment by each unit responsible.

2-19. Pursuit

The exploiting force is aided by cross-country ve-hicles and aircraft. The pursuit force, which musthave high mobility, is mounted, on skis, vehicles,or helicopters. Airborne or airmobile troops arepositioned near defiles to block the retreat of theenemy. During summer, waterways may be usedby the pursuing force as a means of moving pa-trols behind the enemy to destroy bridges anderect road blocks along the enemy lines of retreat.

2-20. Security in the Offensive

When attacking units have large gaps betweenthem and ffanks are vulnerable, patrol and sur-veillance requirements increase. Basically, how-ever, security requirements in the offense duringnorthern operations are no different than in moretemperate zones.

DEFENSIVE OPERATIONS

tures. The defense may also be assumed to encour-

gen-age the enemy to attack under unfavorable condi-tions, such as in long, narrow passes or through

eral reasons as in other areas. It may be necessary deep snow and obstacles where movement is diffi-in northern operation to assume a defensive pos-ture for short periods during breakup or freezeup

cult.

seasons, snow storms, or extremely low tempera- b. Defensive actions are difficult in extreme

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cold because of the requirement to keep troopswarm and in condition to fight. However, im-proved opportunities for the success of the de-fense and counterattack exist since an enemyforce may be exposed to the elements especially ifwarming equipment and other logistical supporthas not accompanied him. The breakup season is

favorable to the defender because trafficability ispoor for the attacker.

c. Conduct of the defense under northern condi-tions is the same as under other conditions. Thetendency to remain shelter bound must be re-sisted. Strong combat patrols are used to harassthe enemy flanks and rear.

d. All-round defense is essential since attacksmay be launched from any direction. Duringspring, summer, and fail a mobile defense is ex-tremely difficult because of trafficability.

e. Routes of supply are often attacked by enemypatrols, therefore, supply personnel must be capa-ble of defense at all times. In rear installations,area security and damage control plans are madeand a warning system established. Special atten-tion is paid to possible landing areas, such aslakes or rivers. When necessary, combat units willfurnish escorts for supply columns.

f. Defense positions located in deep snow sufferless from the effects of enemy fire. Dense for-ests, thickets, fallen timber, cliffs, and other natu-ral obstructions collect snow and create obstaclesto the attacker. Rocks and fallen tree trunks maybecome tank obstacles. The effectiveness of natu-ral terrain obstacles can easily be increased. Theenemy use of frozen waterways can be denied bylaying mine fields in the ice as described in FM3170.

g. Tents are sunk into deep snow or into theground and protected by embankments. If the de-fense is to be of long duration, heated under-ground shelters are constructed and tents areeliminated. It must be remembered, however, thatextensive engineer work is required to build un-derground shelters during the winter. In some

areas, high water tables may preclude construc-tion of underground bunkers and positions. Medi-cal aid stations and command posts are also loca-ted in underground shelters for protection fromenemy fire. Warm shelters are constructed for re-serves. Areas in the defense where there is littlesnow, or which are easily traversed by the enemy,are reinforced with artificial obstacles such as

wire entanglement (especially concertina wire),pitfalls, abatis, antitank mines, and antipersonnelmines and are covered by fire. Deception tech-niques are practiced extensively. Seasonal changeswill affect defense positions. The breakup seasonusually will destroy positions built during thewinter. Positions or obstacles built during the

summer may be made useless by heavy snow fall.h. Special attention must be directed toward

maintaining battle preparedness in winter. Whileresting in forward positions, men must be readyfor combat. Constant care must be taken that allweapons are prepared for immediate use. Firingpositions must be kept clear of snow. Guards arerotated and inspected constantly.

i. Proper security of a defensive position re-quires the location of living and fighting positionsfor the security force on the outer perimeter. Awarning system is established from the security

force position to the forward defense force posi-tion. All movement on the outer edge of the pe-rimeter and in the vicinity of the living-fightingpositions is kept to a minimum to preclude observ-ation or attack by hostile air and ground forces.

2-22. Defense Positions

Strong points should be located on elevated ter-rain. The value of elevated defense positions isgreater during winter than under normal condi-tions because the enemy must attack up hill insnow.

2-23. Composition and Location of Reserves

An aggressive defense requires the formation of aproportionately large reserve with maximumcross-country mobility. Individual oversnowequipment, oversnow vehicles, personnel carriers,or helicopters are used to obtain this mobility.Airmobile reserves may be stationed fartheraway. In selecting a location for the reserve, con-sideration must be given to the importance of restas well as to the probable area of employment.The major portion of the reserve is placed in cov-

ered and concealed positions, protected fromenemy light artillery fire, while the remaindermay be placed closer to the front lines. Trails androads to the probable points of action are pre-pared for the reserve troops and are kept openduring snow storms by elements of the reserve. Sofar as is possible the roads and trails should becamouflaged.

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Section VI. RETROGRADE OPERATIONS

2-24. General 2-25. Withdrawals

Retrograde operations are executed as in normal Withdrawal is best effected at night or underoperations. In the north, suitable conditions are conditions of reduced visibility when enemy reac-

frequently present for leaving strong combat pa- tions are slowest. Trails are broken rearwardfrom positions before withdrawal commences and

trols up to a strength of one or two platoons tomay be mined as the rear guard withdraws. If aharass or ambush the advancing enemy. Surprise daylight withdrawal becomes necessary, smoke

attacks can be launched against columns of vehi- may be used to good effect. Oversnow mobility iscles and troops at natural defiles. In some cases, it exploited to the maximum. During the with-

may be desirable, prior to the withdrawal, to es- drawal, troops destroy all abandoned shelter that

tablish hidden caches of food and ammunition forcan be used by the enemy. Maximum use is madeof mines, traps, and abatis. Airmobile covering

the use of the troops that have been left behind to forces or air cavalry may be employed to goodambush the enemy. advantage to cover withdrawals.

Section VII. AIRMOBILE OPERATIONS

2-26. General

Airmobile operations are particularly adaptable toground operations in northern regions. Generally,northern areas are devoid of the vast air, rail, androad networks common in temperate areas. Thenorthern areas are sparsely settled and small com-munities are often separated by great distancesand isolated from the outside except by small air-craft, watercraft or other, often slow and primi-tive, means of transportation. The terrain pre-sents numerous formidable obstacles such asmountains, swift rivers, extensive lake systems,snow, large expanses of swamp, muskeg, and

dense stands of timber and brush. Airmobileforces can bypass these obstacles and move rap-idly with ground combat and support forces arriv-ing in the objective area ready to fight. Reinforce-ments can be rapidly deployed to the battle areain minimum time. Support can be accomplishedrapidly and effectively under all but the most ad-verse weather conditions. Conventional doctrineis as applicable to northern operations as it is tothe more temperate regions of the world. How-ever, some modifications to operating proceduresare required to overcome the limitation imposedby the environmental conditions.

2-27. Special Factors Affecting NorthernAirmobile Operations

a. Standard Operating Procedure. The capabil-ity of ground combat units and Army aviationunits to conduct airmobile operations must be de-veloped through the conduct of frequent airmobileunit training exercises and the development ofunit standard operating procedures (SOP) fornorthern operations.

b. Loading Plans. SOP should contain detailed

primary and alternate loading plans for all typesof helicopters available in the theater. The avia-tion mission commander or the aviation unit liai-sion officer advises and assists the airmobile taskforce commander in preparing loading plansbased on the lift capabilities of the aircraft. Spe-cific considerations must be given to increasedweight and to the special equipment required forcold weather, mountain and glacier operations. Onmost missions fully loaded rucksacks will be car-ried. So far as is possible, the ahkio, with shelterand supplies and skis or snowshoes must accom-pany the personnel on the same aircraft. Addi-

tional time is required for loading and unloadingwith winter clothing and equipment. Protectionagainst subzero temperatures and other adverseweather conditions may be required when consid-ering external loads.

c. Missions. Missions for the northern airmobileforce are the same as those in other areas withtwo possible exceptions, these are mountain andglacier, and search and rescue operations.

d. Weather. Weather minimums must be estab-lished early in the planning to prescribe the least

acceptable weather in which the task force com-mander will permit the operation to be mounted.Weather factors which must be considered inplanning and conducting northern airmobile oper-ations include: temperature, density altitude,wind speed and direction, icing, visibility, turbul-ence, and snow and ice conditions. Current avia-tion weather forecasts are mandatory. Weatherforecasts notwithstanding, the best source of

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weather information is an on the scene reportmade by a pilot in flight in the area of interest. Ifpossible, a weather reconnaissance flight shouldbe made if weather is marginal or shows signs ofdeteriorating.

e. Aeromedical Evacuation. Plans must be madefor aeromedical evacuation-of the airmobile task

force casualties. The evacuation problem is ofimmediate urgency during periods of subzerotemperatures, because in addition to battle cas-ualties, casualties from cold injury are likely toincrease.

f. Night or Limited Visibility Operations. Thetactical situation may dicate the conduct of airmo-bile operations during darkness or periods of lim-ited visibility. This is particularly true in thenorthern latitudes because of the short periods ofdaylight during the winter months. Flares, heli-copter-mounted searchlights, night vision devices,

and other suitable techniques may be used to illu-minate the area of operations. Airmobile opera-tions may be conducted during bright moonlightnights on snow covered terrain, with little or noartifical light. Areas with deep powdered snowshould be avoided or the interval between helicop-ters greatly increased if more than one aircraft isto land simultaneously.

g. Security Forces. Because of the greatly ex-panded area of responsibility found in a perime-ter-type formation of an airmobile operation, itusually is necessary to economize on the use ofsecurity forces. The security force is further re-

duced because of the requirements to off-loadequipment and construct warming shelters duringcold weather operations. A single security echelonforward of the objective area defense line may beall that is practicable. When combating highlytrained ski troops, it is desirable that all-aroundperimeter security be maintained because of thesecrecy and speed with which ski troops canattack. The forces for the security echelon nor-mally are provided by the forward elements. Toenhance early security for the airmobile assaultand to avoid the tiresome tasks of breaking trail

through deep snow, thick brush or soft muskeg,security forces may land directly on their posi-tions. Air cavalry or other armed aircraft, may beemployed to extend the range of security opera-tions.

h. Planning.(1) The small unit leader must be assured

that he has all of the equipment required toaccomplish the mission and to sustain his unitunder the most adverse climatic conditions. Dur-

ing subzero temperatures individuals must carrytheir existence load (FM 31-70) at all times. Sofar as is possible loading plans must provide roomfor the squad ahkio with shelter and supplies onthe same aircraft as the personnel.

(2) During the winter, skis and snowshoesfor all personnel must be carried on each helicop-

ter and should be tied together to conserve spaceand for ease and speed in loading and off-loading.Skis not tied in a bundle must be carried underthe arms parallel to the ground to prevent themfrom striking the rotor blades on the helicopters.The situation permitting, a trail should be brokento the exact landing site, a landing pad should beprepared and the individuals skis or snowshoesremoved and lashed together to reduce loadingtime. Troops must not be on the landing site attime of touch down.

i. Landing Zone.(1) During winter operations, frozen lakes

should be used as landing zones. Ice thicknessshould be checked by pathfinders before landingsare attempted (table 2). The use of lakes as land-ing zones offer many desirable characteristics; ap-proaches to and from the LZ will be relativelyunobstructed; snow depth will in most cases beless than in sheltered areas; troops can find readyconcealment in trees and vegetation around thelake; and the lake offers a ready-made landingstrip for ski equipped fixed wing aircraft.

(2) Because of the slowness in unloadingtroops and equipment from helicopters during

winter operations, initial landings should not bemade in a defended or hot landing zone. Thelanding zone should therefore be in an undefendedor lightly defended area as close as possible to theobjective area.

j. Landing Operations in Deep Snow. Whenlanding operations are conducted in deep snow,specific techniques are necessary by the airmobileforce.

(1) Because of blowing snow and loss of visi-bility near the ground (fig 2-2), helicopters mayhave to be spaced as much as 100 meters (110yds) apart or may be staggered into the landingzone at 20 to 30 second intervals in powder snowconditions. On wind blown, hardpacked, orcrusted snow, the interval between helicoptersmay be reduced.

(2) Individuals exit utility helicopters withtheir own equipment and move perpendicular tothe line of flight, breaking trail through the snow.On medium cargo helicopters, personnel shouldmove to the rear following the helicopter ski

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tracks when debarking. Other personnel followthe trail made by the lead man. Personnel shouldmove approximately 50 meters (55 yds) or one-half the distance to other helicopters to avoid themaximum wind chill effect and blowing snowcreated by the rotor downwash of the helicopters.Personnel within the radius of the rotor down-wash must protect their faces by turning away

from the main blast and pulling the winter hoodover their heads and around the face. After de-parture of the aircraft, individuals should checkeach other for frostbite.

(3) Unit equipment, ahkios and bundled skis

FM 31-71

or snowshoes, are unloaded as soon as the person-nel have exited the aircraft. The equipment mustbe pulled away from the skis of the helicopter.Small items of equipment must not be thrown intothe snow where they may become lost or blown upinto the rotors.

(4) When the enemy does not have an aerialsurveillance capability, various dyes may be used

on the snow to mark the landing zone for easieridentification on subsequent lifts.(5) When unloading in the landing area,

troops will frequently be completely disoriented.A crew member of individual aircraft should tell

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FM 31-71

the troop commander, as a minimum, which direc-tion is north in relation to which way the aircraftis facing. Direction can easily be established forthe ground commander by landing the helicopterin a predetermined direction. Troop commandersshould orient themselves as completely as possibleprior to touch down so that squad, platoon, andcompany assembly can be accomplished with the

least practicable delay.k. General Procedures and Safety.

(1) During extreme cold conditions, troopwarming areas must be established in the immedi-ate vicinity of the pickup zone and also in thevicinity of the landing zone, if the tactical situa-tion permits. Delays caused by below weather mini-mums are frequent in northern areas. Weatherdecisions should be made as close to the pickuptime as possible. Locating troops in warmingareas immediately adjacent to the pickup zonesimplifies operational requirements. Troops arethen readily available and can react to the mostrecent developments with least delay and are notexposed to the cold during periods of relative in-activity when delays are encountered. Reserveunits which must be immediately available forpickup will require warming tents at the pickupzone while waiting to be committed.

(2) Certain procedures and safety require-ments are similar for both loading and off-loadinghelicopters. In cold weather and deep snow condi-tions, certain precautions take on increased im-portance and must be continuously emphasized

during training and in all operations. The aircraftcommander is the responsible person regardingsafety procedures. To insure maximum safety, allpersonnel should be frequently briefed on the dan-gers of loading and off-loading. The most crucialareas to be concerned with in this briefing are themain and tail rotor blades, and the methods of

approach and departure from the aircraft. Whenoperating in deep snow the vertical clearanceunder the rotor blades is drastically reduced, thuscreating a hazard for personnel departing and ap-proaching the aircraft. The UH-1D may sink inthe snow approximately 61 cm (2 ft), reducingthe normal 236 cm (7 ft 9 in) clearance to ap-proximately 152 cm (5 ft). The helicopter should

be approached and departed only when cleared bythe crew chief. Do not walk directly forward oraft of utility helicopters. Equipment such as indi-vidual weapons, skis and snowshoes must be car-ried under the arms parallel to the ground to pre-vent them from striking the rotor blades. Underno conditions should items be carried on theshoulder when loading or off-loading the aircraft.

(3) Door gunners normally will not be used incold weather operations because of the possibilityof the gunners, flight crew, and passengers get-ting frostbite because of the open doors. Suppres-sive fires must then be conducted by attack heli-copters. It may also be desirable to eliminate doorgunners at other times in order to increase groundcombat power when limited lift is available ordistances are greatly extended.

(4) During lengthy flights the interior tem-perature of the helicopter should be kept rela-tively cool (40

o

F.) to avoid overheating troopsdressed in cold weather clothing.

(5) Attack helicopters provide aerial escortand fire support to the airmobile force the same asin summer operations; however, over-reliance onaircraft rocket point detonating munitions should

be avoided because the fragmentation achieved bythin-skinned ground burst munitions will be mini-mal in deep snow.

l. Detailed Doctrinal Guidance. For detaileddoctrinal guidance on airmobile operations, seeFM 57-35.

Section VIII. COMBAT UNDER CONDITIONS OF LOW VISIBILITY

2-28. General

a. In the unforested regions and those areaswhere natural concealment of any sort is scarce orentirely lacking, it becomes increasingly impor-tant that troops be well trained and familiar withoperations both at night and under conditions oflow visibility arising from blowing snow, mist, orfog.

b. Conditions of low visibility provide the great-est opportunities for surprise. Commanders must

insure that weather forecasts and reports are con-stantly distributed as a matter of standing opera-

ting procedures.

2-29. Night Combat

a. Normal night combat techniques apply un-changed. Movement and control are facilitated bythe increase in visibility resulting from the reflec-tion from the snow. During a cloudy night, lightconditions correspond approximately to those on a

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clear night, with a full moon without snow cover.On windless nights during periods of extremecold, sound carries for great distances. Undersuch conditions, all troops must realize the needfor silence. Otherwise, surprise is impossible toachieve and security difficult to maintain.

b. If the snow has thawed during the day, it

usually freezes at night making movement noisierbut easier than by day. During the spring break-up, daytime thawing usually will restrict the useof roads to night hours.

2-30. Combat During Snowstorms

a. Combat operations are sometimes assisted byhigh winds and snow storms which cover soundand obscure movement. Close reconnaissance andattack are possible under the cover afforded bysuch conditions. The associated high windchill andthe lack of visibility demand a high degree of

training on the part of all troops. Compact forma-tions, simple plans, detailed instructions, limitedobjectives, and positive means of identificationshould be employed.

b. Accurate timing is required so that troops donot remain exposed for prolonged periods of time.If the equivalent chill temperature is low, the

attack should be carried out downwind, if possi-ble, forcing the enemy to face into it.

c. In the defense, particular precautions againstsurprise must be taken during blizzard conditions.The number of listening patrols must be increasedand continual checking will be necessary to insurethat sentries maintain a vigilant watch, particu-larly to the windward and most dangerous flank.

2-31. Combat Under Whiteoutand Fog Conditions

In snow covered terrain, ground irregularities arevisible only by the shadow they cast. Under over-cast the contrast is diminished, and in whiteout orfog it disappears entirely. Movement under suchconditions is extremely difficult, and progress isappreciably reduced. In hilly or mountainouscountry, it may be dangerous since angles of slopecannot be estimated nor can changes in terrain berecognized.

2-32. Recognition

At night and under other conditions of low visibil-ity, there is marked difficulty in distinguishingfriendly from enemy troops when both are wear-ing white. Distinctive markings and signals arenecessary.

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FM 31-71

CHAPTER 3

COMBAT AND COMBAT SUPPORT

Section I.

3-1. General

a. The role of infantry in northern operationsremains essentially the same as in other climates,although the technique of accomplishing a missionmay vary considerably. Units usually are organ-ized into highly mobile, self-sustained tacticalgroupings with only those weapons and equipmentsuited to the operation.

b. The value of surprise is greatly increased inforested areas under conditions of cold and snow.Skillful use of weather conditions, such as fog orblowing snow, can be of great advantage. To in-sure success, plans for infantry operations mustbe made in detail and be made known to everyindividual before action is initiated.

3-2. Cover and Concealment

a. In the forested areas, troop movements areconcealed by the trees. Cover from hostile firemay be constructed from existing timber, by dig-

ging emplacements, and the use of icecrete, snow,and ice. Log and snow covered bunkers may beused for additional protection.

b. In the treeless barren lands, few recognizableterrain features exist. Observation will, at times,be aided by the extreme clarity of the air. In theopen tundra and barren lands of the Arctic, theground is permanently frozen except in some sandand gravel areas, raised beaches, or lakes andriver banks. Even here, frost often lies within afew centimeters of the surface. Consequently, thesiting, construction, and concealment of defense

positions are more difficult than farther south. Inwinter, snow normally is the only constructionmaterial, but fortunately deep hard-packed driftsusually are associated with tactical features. Evenduring the summer, it will often be difficult to digin because of permafrost and poor drainage. Ad-vantage must be taken of every natural object andsurface depression which will provide any degreeof cover and concealment. Breastworks may be

INFANTRY

built by using peat rocks, surface gravel, clumpsof soil, and vegetation. Because of the difficultiesof concealment, dispersion and deception must bepracticed. During these periods, units must usecaution in their movements, as the advantage willlie with the observer who can remain motionless.

3-3. Effect of Terrain on the Accomplishmentof the Infantry Role

Terrain and climate combine to decrease mobilityof infantry units. In summer, muskeg swampsand lakes form barriers which must be sur-mounted or bypassed. When frozen, lakes,swamps, and rivers may often be used as roads.

3-4. Effect of Cold on Infantry Weapns(TM 9-207)

a. In extreme cold, metal becomes brittle. In-creased parts breakage occurs in all types ofweapons.

b.

Many weapons create ice fog which, on a stillday, may obscure the gunners vision; thus requir-ing movement to alternate positions or the use ofa flank observer to direct the fire.

c. Mortars experience an increase in breakageof firing pin

fm 31-71 northern operations (jun 1971)

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