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"Maintaining Direction" from Intelligence Bulletin, December 1942

[Intelligence Bulletin Cover]  
The following article was published in the December 1942 issue of the Intelligence Bulletin.

[DISCLAIMER: The following text is taken from the U.S. War Department Intelligence Bulletin publication. As with all wartime intelligence information, data may be incomplete or inaccurate. No attempt has been made to update or correct the text. Any views or opinions expressed do not necessarily represent those of the website.]

 
MAINTAINING DIRECTION

1. INTRODUCTION

The experience of United Nations troops in the present war has proved the necessity of every soldier's being able to find his way over all types of terrain. The chances of individuals or small groups becoming separated from their units are much greater than in past wars because the use of modern weapons forces a wide dispersal of troops on the battlefield. Small groups also must be sent out on reconnaissance and security missions, and the safety or success of our forces depends on the ability of these groups to find their way back to their units--without much delay.

If you get lost, the worst thing you could do would be to lose your head and get into a state of panic.

Sit down and think the situation over calmly. Where could you have mistaken the way? Were your compass calculations correct? Where could you get back on your route? Nine times out of ten you can discover where you have gone wrong, and find your way back.

This section deals with various ways and means of maintaining direction. Most of the information is based on a lecture given at the British Commando School by Maj. Lord Lovat, the British officer who led the Commando raid against the Norwegian island of Vaagso.1

2. WAYS AND MEANS

a. For Day or Night

Most of the practical ways and means to help in maintaining direction may be used at night as well as during the day, provided some form of light is available (and no patrol should ever go out without some form of light).

(1) Compass.--The compass is the most valuable aid in keeping direction, although experience shows that it is usually impossible to use it when under enemy fire. It also is unreliable in areas where there are lodestone deposits, as in northern Norway. The compass needle may also be deflected by such local objects as cap ornaments, gas masks held in the ready position, and so on.

An oil compass which is remarkably accurate under all conditions has been developed recently. It can be reset on successive bearings at night without the aid of a light--a great advantage over other compasses.

At night, during bad weather, among mountains, or when under enemy observation, it is usually impossible to unfold and examine a map. It is therefore better to prepare a traverse card giving the distance and compass bearings from point to point along the route. The bearings should be taken off the map with a transparent protractor and then converted. The distances should be measured off the map in yards. By day and by night every man should compare his paces against a measured distance, up and down hill and along the level. Distance can also be checked by estimation of time--for instance, a man may know from experience that he travels at 4 miles per hour on a level road and 2 1/4 over rough country.

In thick mist, the party, if small, travels in single file so that each man keeps in sight of the man in front of him. The last man takes a bearing and sees that the leader sets off in the right direction (the leader marches on a definite point, or line of points, if visibility allows). The man with the compass frequently checks the distance and, after getting the attention of the leader, signals him to the right or left by pointing. When the leader is on line again, the man with the compass holds his arm above his head. In this manner, a surprising degree of accuracy can be attained, especially if each leg of the traverse ends at some easily recognized place, such as the top of a hill, a small lake or pond, or the junction of two streams. An error of 50° often throws one off only 150 yards to a mile.

(2) Maps.--From a map a soldier can memorize a route by noting the outstanding features, such as ridges and water courses. Much practice is needed in using maps. It is very helpful to work out the easiest route between two places over rough country, and then to follow it exactly to see if it really is the best way. A good map reader can actually visualize the country by examining a map of it. He knows from the direction of a slope what vegetation to expect, and whether a certain route will be dry or wet underfoot.

(3) Trees.--The branches of trees grow away from the direction of prevailing winds in exposed countries and their roots are much more prominent on the windward side. Therefore, by knowing the direction from which these winds come, it is easy to determine the approximate position of north, south, east, west, and intermediate points.

In many countries moss and lichen grow only on the north (sunless) side of trees and rocks, and the bark of trees usually is thicker on the north side.

(4) Wind.--The wind usually is fairly constant at certain times of the day and year in most localities. One of the best ways to find the exact direction of the wind is to toss up a handful of dried grass or a few loose strands pulled from a woolen garment and allow them to float down. If clouds are used to indicate the direction of wind, only those directly overhead show the true direction. Even then, the wind may be different higher in the sky. In country covered with snow or sand, the angle of the drifts shows the direction of the prevailing and subsidiary winds. (Always move upwind if possible, because you can hear the enemy better and he has greater difficulty in hearing you. You can also detect suspicious smells better.)

(5) Marks.--Following streams or ridges until you reach an area in which you know your way is one method to use if you are lost. If you are searching for your camp, which you know lies on a river or trail in a certain direction that you know roughly, do not try to go directly toward it, but go definitely to one side, so that when you reach the river or trail you will know which way to turn for your camp.

A knowledge of tracking is a valuable asset and provides much pleasure. A good tracker, on suitable ground, can tell exactly what has occurred out of the ordinary. He knows the number and formation of the enemy, the speed of his movement, and many other details that the average person would not be able to determine. If you are following enemy tracks, be careful that they do not lead you into an ambush.

At night there are various points to remember. When a bearing has been taken, it is helpful to hold a whitened (chalked) stick at about 45° as a prolongation of the axis of the compass needle. The stick will cut the horizon at a spot which can then be used to march on. The compass reader then sends out an assistant on the line until he is barely visible. Say, for instance, he stops 160 yards out. The man with the compass checks to see whether his assistant actually is on line, and then proceeds to the new point. From this spot another point on the horizon is selected, and the assistant is directed to go 150 yards in that direction and stop without any signal. The compass reader repeats the same procedure as before, and the group keeps on its bearing—advancing 150 yards at a time. To check the hundreds when counting paces, it is a good idea to carry 10 pebbles or matches in one pocket and transfer one to another at the end of each hundred.

(6) Altimeter.--This instrument is useful as a check as long as it is set at a known height. For example, if a man is lost and finds himself at the top of a mountain, at a crossroad, or some other spot which would be shown on the map, a knowledge of the height of the mountain or crossroad would help to identify it on the map.

b. For Day Only

(1) The Sun.--The sun, in the Northern Hemisphere, is due south at midday. Since it moves 360° in 24 hours (15° per hour), the south point can be found if the time is known.

A more accurate method is as follows: Stand a pencil upright. (This can be done by sticking its base onto a penny with sealing wax or wax from a candle.) Draw a circle around it with a radius about as long as the pencil. The shadow of the pencil will fall outside the circle in the morning, will shorten as the sun rises higher, will fall well within the circle at midday, and will lengthen during the afternoon until it cuts the circle a second time and again falls outside it. Mark the point at which it cuts the circle (this will occur at about 1000 hours and 1400 hours), bisect the line joining these two points, and the true north line will run from the base of the pencil through the center of this line. This method is accurate within a few degrees.

(2) Sun compass.--The sun compass is essentially a shadow compass, and must be reset at frequent intervals as the sun's declination changes. It has immense advantages over the magnetic compass for land navigation. Entirely unaffected by its surroundings, it can be made as accurate and precise as the operator desires. It gives true bearings, is easy to read, and is more sturdy. On the other hand, this compass can only be used when the sun is shining and when so mounted that the sun can fall on it unobstructed. Hence the compass is the complement of, and not a substitute for, the magnetic compass. Both must be available for the navigator, who uses the sun compass whenever possible, reserving the magnetic compass for sunless periods.

All types of sun compasses consist essentially of a vertical needle set at the center of a horizontal plate upon which the needle's shadow falls. The sun compass has no deviation, but the direction of the shadow (which corresponds to the variation in the magnetic compass) changes widely, though in a definite way, throughout the day, and at the same time of day from week to week and from one latitude to another. The sun compass, being liable to no errors, has long been used at sea for checking the deviation of the ship's magnetic compass. The sun's azimuth throughout the day for all latitudes and declinations are given in azimuth tables.2 The original setting and the corrections on the sun compass are obtained from an almanac.

(3) Watch.--If you have a watch, point the hour hand at the sun and bisect the angle between the hour hand and 1200 hours. This will give you true south. (After 1600 hours this angle must be measured in the direction that the hour hand has already traveled.

(4) Study of Terrain.--Any group to be sent out over terrain unfamiliar to them should make a careful study on the map of the areas it may cover, fixing in mind the general and prominent features and taking notes on these for study en route. Members of the group should observe the terrain carefully as they go out, in order to become familiar with landmarks or any other prominent features.

c. For Night Only

At night the sense of sound largely takes the place of sight, and the sense of smell may also prove valuable--especially with practice--in identifying the presence of animals, or certain kinds of vegetation, or the vicinity of water. At night, observe and remember the shape of skylines.

Stars are an excellent aid in maintaining direction--the greatest, in fact--and an intimate knowledge of them relieves the loneliness and strangeness of solitary work at night. A specialist's knowledge is needed to find direction by the moon and planets.

The pole star is never more than 20 degrees away from True North (the error is at its maximum when a line joining the pole star to a point midway between the two end stars of the handle of the plough, is vertically above, or vertically below, the pole star). The pole star can be seen from the pointers, from Cassiopeia, or--if the north stars are all hidden--from Orion, although Orion is out of sight from May 20 to July 20.

If stars are being used in a compass march, take one at about 30 degrees altitude. If it is low, it may be lost in mist and will disappear if you descend into a valley; and if it is higher, you will get a crick in the neck by constantly observing it. Do not forget that a star is liable to swing in a counter-clockwise direction as much as 15 degrees per hour.

d. In the Desert

One of the most striking resemblances of desert warfare to naval warfare is in the widespread use of navigation. Landmarks are few, and at night even these few are practically impossible to see. Desert navigation consists essentially of setting a course by compass and following it by dead reckoning--that is, by traveling a measured distance. Before commencing a march, the destination is selected on the map, its compass bearing is measured with a protractor, and its distance is scaled off. The compass bearing is then set on a sun compass, which is mounted on each vehicle.

Distance is measured on the odometer (a mileage indicator), which must be carefully calibrated and kept in adjustment. The odometer is geared for a tire of a particular size. The navigator must therefore check his mileage indicator against a measured distance along a road with mile or kilometer marks, especially when using oversize "sand" tires. He then obtains a correction factor to be applied to all indicated distances. For ordinary work this factor may be small enough to be disregarded. In addition to the above constant-distance error, the mileage indicated by the same vehicle may vary by as much as 2 percent, according to the terrain, the speed, and the load. A good navigator tries to know his vehicle as quickly as possible.

Foot troops measure the distance marched by counting paces or using a pedometer. If a dismounted guide is used, several pace counters are employed. For night travel, a unit can guide on a star, provided the officers and men are trained to identify the stars and planets, and know how they change their positions in the heavens. A pocket chart is useful.

The marking of routes for night marches is accomplished as follows: The route is reconnoitered, during daylight hours if possible, and is marked. Each marker consists of an oil can, set on top of a stake, with a light inside the can. A small slit in one side of the can serves as a marker; the dot of light can be seen for miles to the rear.

1 For details on how to use compasses and maps, see chapter 12 of the Soldier's Handbook. Another excellent source for additional information on how to maintain direction is a small book entitled Field Navigation, Part I, Dead Reckoning, published by the Army Map Service, Washington, D.C.
2 Azimuth: an arc of the horizon measured clockwise between a fixed point (in navigation, usually the north point) and the vertical circle passing through the center of an object.

 

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