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5-7. Effects of Environment

a. General. Basically, mapreading, as well as navigation under cold weather conditions, follows the same principles as in the temperate zones. In addition to the normal procedures, every individual must be most familiar with certain conditions peculiar to the cold weather regions and the techniques applicable to navigation. Due to the fact that a technical failure or human error may easily, and especially in the winter, be fatal to the individual or to a unit, great care must be exercised when navigating in low temperatures.
b. Navigation Problems. The following conditions, characteristic of the cold weather regions, will make accurate navigation very difficult:
(1) Lack of adequate large scale maps in the sparsely populated areas which will increase the requirements for and the use of aerial photographs.
(2) Photos of many areas will be difficult to read and interpret because of the absence of relief and contrast, and absence of manmade works for use
as reference points.
(3) Dense forests and wildernesses offer few landmarks and limit visibility. Also, barren, monotonous tundra areas north of the tree line are characterized
by lack of landmarks as aids for navigation.
(4) In winter, short daylight, fogs, snowfall, blizzards, drifting snow, especially in the barren areas, drastically limit visibility. At times an overcast sky and snow-covered terrain create a phenomenon called whiteout which makes recognition of irregularities in terrain extremely difficult.
(5) Heavy snow may completely obliterate existing tracks, trails, outlines of small lakes, and similar landmarks. Because the appearance of the terrain
is quite different in winter from that in summer, particular attention must be paid to identifying landmarks, both on the ground and in aerial photos.
(6) Magnetic disturbances are encountered, making magnetic compass readings difficult and sometimes unreliable.
(7) Magnetic declination in different localities varies considerably, and must be taken into consideration when transposing from a map to a compass.
(8) Handling maps, compass, and other navigation instruments in low temperatures with bare hands is difficult. Removing handgear may often be
possible for a very short period of time only.

5-8. Methods of Land Navigation
a. The normal methods of land navigation under cold weather conditions remain the same as anywhere else. Maps and aerial photos may be used alone during daylight in terrain which offers enough distinctive terrain features to serve as useful landmarks. They may also be used in conjunction with a compass, especially in terrain which contains insufficient landmarks or under circumstances when visibility is limited. However, in most instances, utilizing
the map and compass together will provide for the surest land navigation in northern areas of operation.
b. Depending on various conditions, certain supplementary methods, such as position of the sun in daytime, North Star and Big Dipper at night, as described in FM 21-26, may be used to aid in land navigation. Where possible, these methods should be employed in conjunction with the normal methods described above.
c. It is obvious that on vast barren grounds as well as in wide forest, navigation by dead reckoning often becomes the only practical method. Dead reckoning is the process by which position at any instant is found by applying to the last determined position the direction and distance of the course traveled. This method should also be used in areas where landmarks are very limited or totally nonexistent. It is also desirable when the landmarks
are obliterated by the limited visibility.

5-9. Navigation by Dead Reckoning
Navigation by dead reckoning is performed in accordance with FM 21-26. Due to the peculiarities of the cold weather regions, the following hints should be observed when applicable:
a. Responsibility for navigation is assigned to a detail of one officer or noncommissioned officer and 1 to 2 men, all thoroughly experienced in navigation techniques. The detail is placed directly under the control of the unit commander and must be released from the carrying of individual heavy loads and from details such as trailbreaking in order to perform their duties properly. Using a small detail rather than a single navigator is based upon the fact that the method of pacing distances in deep snow has to be modified as described in c below.
b. In general, the navigation detail is responsible for—
(1) Accumulating necessary instruments and equipment.
(2) Keeping instruments and equipment serviceable.
(3) Performing the detailed duties of taking and recording necessary data for precise location at all times.
(4) Maintaining liaison with the commander of the unit.
(5) Supplying data to keep the column on course.
c. Due to the sliding capacity of the skis, normal pacing system is very inaccurate or, in certain cases, such as on steep slopes, entirely useless. Pacing on snowshoes can be done in emergency. It must be borne in mind, however, that an individual mounted on snowshoes takes much shorter paces than on foot. The only recommended method for accurate ground measurements is a piece of line or field wire preferably 50 meters long (50 yds) used by
two navigators.
d. Keeping a log is mandatory. The preparation of the log, as well as plotting the route from the log data on the face of the map or on a separate piece of paper at the same scale as the map, must be completed prior to the departure to minimize the use of instruments and equipment in low temperatures with bare hands.
e. Certain mechanized aids are highly valuable for navigation by dead reckoning.
(1) A magnetic compass has been developed for mounting in all vehicles.
(2) Odograph Ml is an instrument which automatically plots the course of a moving vehicle. It consists of three principal units-the compass; the plotting unit; and the powerpack. All components are interconnected by electric cable and flexible shafts. It was originally designed for use in the 1/4-ton truck, but can be used in other vehicles to include track-laying vehicles and sleds for operation under winter conditions.
(3) Odograph M2 is much more accurate and convenient to use than the Ml. It utilizes the miniature gyro-compass for the input of direction. In normal operations, if the map coordinates of the starting point are set on the instrument, it will provide the true coordinates of any point along the course of travel.
(4) The use of rotary wing aircraft for “pathfinding” in bush country greatly assists in land navigation. From the tactical point of view, however, it is less feasible because it tends to disclose the movement. Troops can reveal their position to the aircraft by the use of colored smoke. The pilot can then give them their position location by radio or dropped message.

5-10. General

Prior march reconnaissance includes memorizing details of the country to be traversed. Routes should be plotted and as many landmarks located as possible to insure that personnel will not be without recognizable features for any appreciable length of time. If on barren terrain, all navigation instruments must be thoroughly checked and one of the most experienced men should be given the job of navigating and maintaining the “dead reckoning log.” It is possible to become temporarily lost while operating in friendly areas of enemy terrain, as on a long range patrol. Each situation should be considered separately, and the main point to remember in any case is to remain calm.

5-11. When Lost Within Known Locality
If the sector is quiet and there is an absence of war noises or aircraft to guide the patrol toward friendly lines, stop in place. In a wooded area steps should be retraced to the last known point. If this is not practical, estimate the present location and send a small detail in search of the next known point. Opinions should be taken from the group as a whole if it is felt they will contribute. Search parties must mark their trail carefully in order that they may return and guide the main group forward or rejoin the group should their search be fruitless. In the meantime, the remainder of the group should seek shelter. If it is still not possible to locate the route, carry out the group action discussed in paragraph 5-12.

5-12. Conduct When Lost
At the first suspicion that a patrol or unit is not on the right course, it should not keep moving in the hope that it will come across a known landmark. The leader should halt the patrol, not cause unnecessary panic by appearing concerned, and immediately make a detailed check of the route starting at the last known point passed. If extensive checking of the position does not clarify the situation, inform all concerned personnel of the circumstances. When it has been determined the group is definitely lost, the patrol leader must accomplish the following:
a. Seek a shelter, evaluate the situation, and formulate a plan.
b. Gather all food and drink and institute a rationing system.
c. Send a few selected personnel to search for a route, while the balance of the party remains in a sheltered position.
d. Arrange necessary ground-to-air signals appendix B.

5-13. Track-Laying Vehicles

a. General. So far as small units and individuals are concerned, vehicles of the tracklaying type are the best aid to movement in northern regions. Deep snow and extreme cold impose special problems of operations and maintenance (app. F). Mandatory characteristics of any vehicle to be used in support of
small units and individuals in the Far North during all seasons are mobility over muskeg and tundra, through brush and light timber, and the ability to reak trail in deep snow. A complete discussion of these problems is beyond the scope of this manual. This manual is limited to a brief discussion of the general capabilities and employment of vehicles which are capable of tactical cross-country movement during all seasons. In order to conserve the energy of troops, mechanized transportation of heavy weapons, ammunition, tentage, sleeping equipment, rations, and individual packs must be utilized to the maximum. Troops burdened with carrying or pulling these items soon become exhausted and lose their mobility and fighting capacity. Wheeled vehicles are generally restricted to road movements and have little use in cross-country operations of small units. The series of pictures contained in figures 5-6 through 5-12 illustrate construction problems entailed in negotiating winter trails with track-laying vehicles.
b. Tractor Trains. The purpose of tractor trains is to furnish oversnow movement of supplies and equipment. Tractor trains will be utilized normally from a railhead, truckhead, or airhead to the division or brigade support area. The tractor train is a means of moving large quantities of supplies cross-country. The trains are composed of cargo sleds drawn by construction type tractors and normally, due to their size and slow rate of march, are not used forward of the brigade support area. The tractor train in no way takes the place of wheeled cargo carriers that may be able to operate on roads or trails.

5-14. The Full Track Personnel Carried
The full track cross-country carriers are considered to be the best vehicles for use by combat troops in the North. The armored and unarmored carriers are capable of transporting a complete rifle squad together with its equipment and impedimenta. In an emergency these vehicles can furnish limited heat, shelter, and sleeping accommodations. The design of these carriers permits their functioning as cargo and weapons carriers, as command posts, or for evacuation of litter patients. While the armored carrier is capable of reconnaissance, mounts armament, and has armor protection from small arms fire, the unarmored carrier provides better mobility and greater range on less fuel. The inclosed watertight hulls provide an amphibious capability and some protection against radioactive fallout.

5-15. Tanks
Tanks are designed for cross-country mobility to include traveling in deep snow. In addition to their normal tactical missions they may be employed to transport personnel in an appreach march and, in an emergency, to tow skiers. Windchill factors must be taken into consideration prior to moving troops on tanks for any appreciable distance to insure against frostbite. Tanks may also be used to pull cargo sleds; however, damage can be caused to sled tongues by the fast, jerky starting which is characteristic of tanks. Tank tracks may provide routes of advance for troops, especially in the assault phase of the attack.

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