CHAPTER 11

TERRAIN ASSOCIATION

Failure to make use of the vast amounts of information presented by the map and available to the eye on the ground will seriously reduce your chances for success in land navigation. The soldier who has repeatedly practiced the skills of identifying and discriminating among the many types of terrain an other features, knows how these features are mapped, can begin to visualize the shape of the land by studying the map, can estimate distances, and can perform quick resection from the many landmarks he sees is the one who will be at the right place to help defeat the enemy on the battlefield. This chapter tells how to orient a map with and without a compass, how to find locations on a map as well as on the ground, how to study the terrain, and how to move on the ground using terrain association and dead reckoning.

11­1. ORIENTING THE MAP

The first step for a navigator in the field is orienting the map. A map is oriented when it is in a horizontal position with its north and south corresponding to the north and south on the ground. Some orienting techniques follow:

a. Using a Compass. When orienting a map with a compass, remember that the compass measures magnetic azimuths. Since the magnetic arrow points to magnetic north, pay special attention to the declination diagram. There are two techniques.

NOTE: Once the map is oriented, magnetic azimuths can be determined with the compass, but the map should not be moved from its oriented position; any change in its position will move it out of line with magnetic north. (See paragraph 11-6b[1]).

NOTE: Special care should be taken whenever orienting your map with a compass. A small mistake can cause you to navigate in the wrong direction.

b. Using Terrain Association. A map can be oriented by terrain association when a compass is not available or when the user has to make many quick references as he moves across country. Using this method requires careful examination of the map and the ground, and the user must know his approximate location (Figure 11-5). Orienting by this method is discussed in detail in paragraph 11-3.

c. Using Field-Expedient Methods. When a compass is not available and there are no recognizable terrain features, a map may be oriented by any of the field­expedient methods described in paragraph 9­5. Also see Figure 11-6.

11­2. LOCATIONS

The key to success in land navigation is to know your location at all times. With this basic knowledge, you can decide what direction and what distance to travel.

a. Known Position. Most important of all is the initial location of the user before starting any movement in the field. If movement takes place without establishing the initial location, everything that is done in the field from there on is a gamble. Determine the initial location by referring to the last known position, by grid coordinates and terrain association, or by locating and orienting your position on the map and ground.

b. Known Point/Known Distance (Polar Plot). This location can be determined by knowing the starting point, the azimuth to the desired objective, and the distance to it.

c. Resection. See Chapter 6.

d. Modified Resection. See Chapter 6.

e. Intersection. See Chapter 6.

f. Indirect Fire. Finding a location by indirect fire is done with smoke. Use the point of impact of the round as a reference point from which distances and azimuth can be obtained.

11­3. TERRAIN ASSOCIATION USAGE

The technique of moving by terrain association is more forgiving of mistakes and far less time consuming than dead reckoning. It best suits those situations that call for movement from one area to another. Errors made using terrain association are easily corrected because you are comparing what you expected to see from the map to what you do see on the ground. Errors are anticipated and will not go unchecked. You can easily make adjustments based upon what you encounter. Periodic position-fixing through either plotted or estimated resection will also make it possible to correct your movements, call for fire, or call in the locations of enemy targets or any other information of tactical or logistical importance.

a. Matching the Terrain to the Map by Examining Terrain Features. By observing the contour lines in detail, the five major terrain features (hilltop, valley, ridge, depression, and saddle) should be determined. This is a simple task in an area where the observer has ample view of the terrain in all directions. One by one, match the terrain features depicted on the map with the same features on the ground. In restricted terrain, this procedure becomes harder; however, constant checking of the map as you move is the determining factor (Figure 11­5).

b. Comparing the Vegetation Depicted on the Map. When comparing the vegetation, a topographic map should be used to make a comparison of the clearings that appear on the map with the ones on the ground. The user must be familiar with the different symbols, such as vineyards, plantations, and orchards that appear on the legend. The age of the map is an important factor when comparing vegetation. Some important vegetation features were likely to be different when the map was made. Another important factor about vegetation is that it can change overnight by natural accidents or by man (forest fires, clearing of land for new developments, farming, and so forth).

c. Masking by the Vegetation. Important landforms could be camouflaged by the vegetation, making it harder for the navigator to use terrain association.

d. Using the Hydrography. Inland bodies of water can help during terrain association. The shape and size of lakes in conjunction with the size and direction of flow of the rivers and streams are valuable help.

e. Using Man-Made Features. Man­made features could be an important factor during terrain association. The user must be familiar with the symbols shown in the legend representing those features. The direction of buildings, roads, bridges, high­tension lines, and so forth will make the terrain inspection a lot easier; however, the age of the map must be considered because man­made features appear and disappear constantly.

f. Examining the Same Piece of Terrain During the Different Seasons of the Year. In those areas of the world where the seasons are very distinctive, a detailed examination of the terrain should be made during each of the seasons. The same piece of land will not present the same characteristics during both spring and winter.

g. Following an Example of Terrain Association. Your location is hilltop 514 in the lower center of the map in Figure 11­7.

11­4. TACTICAL CONSIDERATIONS

Military cross­country navigation is intellectually demanding because it is imperative that the unit, crew, or vehicle survive and successfully complete the move in order to accomplish its mission. However, the unnecessary use of a difficult route will make navigation too complicated, create more noise when proceeding over it, cause wear and tear on equipment and personnel, increase the need for and needlessly complicate recovery operations, and waste scarce time. On receipt of a tactical mission, the leader begins his troop­leading procedures and makes a tentative plan. He bases the tentative plan on a good terrain analysis. He analyzes the considerations covered in the following mnemonics-- OCOKA and METT­T.

a. OCOKA. The terrain should be analyzed for observation and fields of fire, cover and concealment, obstacles, key terrain, and avenues of approach.

b. METT­T. Tactical factors other than the military aspects of terrain must also be considered in conjunction with terrain during movement planning and execution as well. These additional considerations are mission, enemy, terrain and weather, troops, and time available.

11­5. MOVEMENT AND ROUTE SELECTION

One key to success in tactical missions is the ability to move undetected to the objective. There are four steps to land navigation. Being given an objective and the requirement to move there, you must know where you are, plan the route, stay on the route, and recognize the objective.

a. Know Where You Are (Step 1). You must know where you are on the map and on the ground at all times and in every possible way. This includes knowing where you are relative to--

This step is accomplished by knowing how to read a map, recognize and identify specific terrain and other features; determine and estimate direction; pace, measure, and estimate distances, and both plot and estimate a position by resection.

b. Plan the Route (Step 2). Depending upon the size of the unit and the length and type of movement to be conducted, several factors should be considered in selecting a good route or routes to be followed. These include-

In other words, the route must be the result of careful map study and should address the requirements of the mission, tactical situation, and time available. But it must also provide for ease of movement and navigation.

c. Stay on the Route (Step 3). In order to know that you are still on the correct route, you must be able to compare the evidence you encounter as you move according to the plan you developed on the map when you selected your route. This may include watching your compass reading (dead reckoning) or recognizing various checkpoints or landmarks from the map in their anticipated positions and sequences as you pass them (terrain association). Or, better still, it should be a combination of both.

d. Recognize the Objective (Step 4). The destination is rarely a highly recognizable feature such as a dominant hilltop or road junction. Such locations are seldom missed by even the most inexperienced navigators, but they are often dangerous places for soldiers to occupy. The relatively small, obscure places are most likely to be the destinations.

11­6. NAVIGATION METHODS

Staying on the route is accomplished through the use of one or two navigation techniques-dead reckoning and terrain association. Each method will now be discussed in detail.

a. Moving by Dead Reckoning. Dead reckoning consists of two fundamental steps. The first is the use of a protractor and graphic scales to determine the direction and distance from one point to another on a map. The second step is the use of a compass and some means of measuring distance to apply this information on the ground. In other words, it begins with the determination of a polar coordinate on a map and ends with the act of finding it on the ground.

b. Moving by Terrain Association. The technique of moving by terrain association is more forgiving of mistakes and far less time­consuming than dead reckoning. It best suits those situations that call for movement from one area to another (Figure 11­8). Once an error has been made in dead reckoning, you are off the track. Errors made using terrain association are easily corrected, however, because you are comparing what you expected to see from the map to what you do see on the ground. Errors are anticipated and will not go unchecked. You can easily make adjustments based upon what you encounter. After all, you do not find the neighborhood grocery store by dead reckoning--you adjust your movements according to the familiar landmarks you encounter along the way (Figure 11­8). Periodic position-fixing through either plotted or estimated resection will also make it possible to correct your movements, call for fire, or call in the locations of enemy targets or any other information of tactical or logistical importance.

c. Combination of Techniques. Actually, the most successful navigation is obtained by combining the techniques described above. Constant orientation of the map and continuous observation of the terrain in conjunction with compass­read azimuths, and distance traveled on the ground compared with map distance, used together make reaching a destination more certain. One should not depend entirely on compass navigation or map navigation; either or both could be lost or destroyed.

11­7. NIGHT NAVIGATION

Darkness presents its own characteristics for land navigation because of limited or no visibility. However, the techniques and principles are the same that are used for day navigation. The success in nighttime land navigation depends on rehearsals during the planning phase before the movement, such as detailed analysis of the map to determine the type of terrain in which the navigation is going to take place and the predetermination of azimuths and distances. Night vision devices (see Appendix H) can greatly enhance night navigation.

a. The basic technique used for nighttime land navigation is dead reckoning with several compasses recommended. The point man will be in front of the navigator but just a few steps away for easy control of the azimuth. Smaller steps are taken during night navigation, so remember, the pace count will be different. It is recommended that a pace count obtained by using a predetermined 100­meter pace course be used at night.

b. Navigation using the stars is recommended in some areas; however, a thorough knowledge of constellations and location of stars is needed (see paragraph 9­5c). The four cardinal directions can also be obtained at night by using the same technique described for the shadow­tip method. Just use the moon instead of the sun. In this case, the moon has to be bright enough to cast a shadow.