FIELD MANUAL NO. 90-5 *FM 90-5 HEADQUARTERS DEPARTMENT OF THE ARMY Washington, DC, 16 August 1982 JUNGLE OPERATIONS CONTENTS DISTRIBUTION RESTRICTION: Approved for public release; distribution is unlimited. *This publication supersedes FM 31-35, 26 September 1969. The words “he,” “him,” “his,” “man,” and “men,” when used in this publication, represent both the masculine and feminine genders unless otherwise specifically stated. You may recommend changes to this manual to improve it. Key your comments to the page and line of text in which the changes are recommended. Give reasons for each comment to help understand and evaluate it. Send comments to: Commandant, United States Army Infantry School, ATTN: ATSH-B-ID, Fort Benning, Georgia 31905. ii FM 90-5 CHAPTER 1 The Jungle Environment Section I. GENERAL This chapter introduces jungle environ- ments—where they are found and what they are like. Later chapters build on this information, providing guidance on fighting and living in the jungle. Field Marshal Slim’s words reflect the image of the jungle most armies carry into jungle warfare. At first, the jungle seems to be very hostile, but the hostility wanes as troops learn more about the jungle environ- ment. Jungles, in their various forms, are common in tropical areas of the world— mainly Southeast Asia, Africa, and Latin America. “To our men. . . the jungle was a strange, fearsome place; moving and fighting in it were a nightmare. We were too ready to classify jungle as 'impenetratable' . . . To us it appeared only as an obstacle to movement; to the Japanese it was a welcome means of concealed maneuver and suprise . . . The Japanese reaped the deserved reward . . . we paid the penalty.” –Field Marshall Slim, Victor in Burma, World War II (Concerning the dark, early days of the Burma Campaign) CONTENTS SECTION PAGE I. General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 II. Climate and Weather. . . . . . . . . . . . . . . . . . 1-2 Ill. Terrain and Vegetation . . . . . . . . . . . . . . . 1-3 1-1 —FM 90-5 Section II. CLIMATE AND WEATHER The climate in jungles varies with location. Close to the equator, all seasons are nearly alike, with rains throughout the year; farther from the equator, especially in India and Southeast Asia, jungles have distinct wet (monsoon) and dry seasons. Both zones have high temperatures (averaging 78 to 95+ degrees Fahrenheit), heavy rainfall (as much as 1,000 centimeters [400+ inches] annually), and high humidity (90 percent) throughout the year. Severe weather also has an impact on tactical operations in the jungle. The specific effects of weather on operations are discussed throughout this manual. 1-2 FM 90-5 – Section III. TERRAIN AND VEGETATION TYPES OF JUNGLES The jungle environment includes densely forested areas, grasslands, cul- tivated areas, and swamps. Jungles are classified as primary or secondary jungles based on the terrain and vegetation. PRIMARY JUNGLES These are tropical forests. Depending on the type of trees growing in these forests, primary jungles are classified either as tropical rain forests or as deciduous forests. Tropical Rain Forests. These consist mostly of large trees whose branches spread and lock together to form canopies. These canopies, which can exist at two or three different levels, may form as low as 10 meters from the ground. The canopies prevent sunlight from reaching the ground, causing a lack of undergrowth on the jungle floor. Extensive above-ground root systems and hanging vines are common. These conditions, combined with a wet and soggy surface, make vehicular traffic difficult. Foot movement is easier in tropical rain forests than in other types of jungle. Except where felled trees or construction make a gap in the canopy of the rain forest, observation from the air is nearly impossible. Ground observation is generally limited to about 50 meters (55 yards). Deciduous Forests. These are found in semitropical zones where there are both wet and dry seasons. In the wet season, trees are fully leaved; in the dry season, much of the foliage dies. Trees are generally less dense in deciduous forests than in rain forests. This allows more rain and sunlight to filter to the ground, producing thick undergrowth. In the wet season, with the trees in full leaf, observation both from the air and on the 1-3 – FM 90-5 ground is limited. Movement is more difficult than in the rain forest. In the dry season, however, both observation and trafficability improve. SECONDARY JUNGLES These are found at the edge of the rain forest and the deciduous forest, and in areas where jungles have been cleared and abandoned. Secondary jungles appear when the ground has been repeatedly exposed to sunlight. These areas are typically overgrown with weeds, grasses, thorns, ferns, canes, and shrubs. Foot movement is extremely slow and difficult. Vegetation may reach to a height of 2 meters. This will limit observation to the front to only a few meters. COMMON JUNGLE FEATURES SWAMPS These are common to all low jungle areas where there is water and poor drainage. There are two basic types of swamps— mangrove and palm. Mangrove Swamps. These are found in coastal areas wherever tides influence water flow. The mangrove is a shrub-like tree which grows 1 to 5 meters high. These trees have tangled root systems, both above and below the water level, which restrict movement to foot or small boats. Observation in mangrove swamps, both on the ground and from the air, is poor. Concealment is excellent. Palm Swamps. These exist in both salt and fresh water areas. Like movement in the mangrove swamps, movement through palm swamps is mostly restricted to foot (sometimes small boats). Vehicular traffic is nearly impossible except after extensive road construction by engineers. Observation and fields-of-fire are very limited. Concealment 1 - 4 FM 90-5 – from both air and ground observation is excellent. SAVANNA This is a broad, open jungle grassland in which trees are scarce. The thick grass is broad-bladed and grows 1 to 5 meters high. Movement in the savanna is generally easier than in other types of jungle areas, especially for vehicles. The sharp-edged, dense grass and extreme heat make foot movement a slow and tiring process. Depending on the height of the grass, ground observation may vary from poor to good. Concealment from air observation is poor for both troops and vehicles. BAMBOO This grows in clumps of varying size in jungles throughout the tropics. Large stands of bamboo are excellent obstacles for wheeled or tracked vehicles. Troop movement through bamboo is slow, exhausting, and noisy. Troops should bypass bamboo stands if possible. CULTIVATED AREAS These exist in jungles throughout the tropics and range from large, well-planned and well-managed farms and plantations to small tracts cultivated by individual farmers. There are three general types of cultivated areas—rice paddies, plantations, and small farms. Rice Paddies. These are flat, flooded fields in which rice is grown. Flooding of the fields is controlled by a network of dikes and irrigation ditches which make movement by vehicles difficult even when the fields are dry. Concealment is poor in rice paddies. Cover is limited to the dikes, and then only from ground fire. Observation and fields of fire are excellent. Foot movement is poor when the fields are wet because soldiers must 1-5 — FM 90-5 wade through water about 1/2 meter (2 feet) deep and soft mud. When the fields are dry, foot movement becomes easier. The dikes, about 2 to 3 meters tall, are the only obstacles. Plantations. These are large farms or estates where tree crops, such as rubber and coconut, are grown. They are usually carefully planned and free of undergrowth (like a well-tended park). Movement through plantations is generally easy. Observation along the rows of trees is generally good. Concealment and cover can be found behind the trees, but soldiers moving down the culti- vated rows are exposed. Small Farms. These exist throughout the tropics. These small cultivated areas are usually hastily planned. After 1 or 2 years’ use, they usually are abandoned, leaving behind a small open area which turns into secondary jungle. Movement through these areas may be difficult due to fallen trees and scrub brush. Generally, observation and fields-of-fire are less restricted in cultivated areas than in uncultivated jungles. However, much of the natural cover and concealment are removed by cultivation, and troops will be more exposed in these areas. 1-6 FM 90-5 CHAPTER 2 Life in the Jungle Section I. GENERAL Soldiers must understand that the environment affects everyone. The degree to which soldiers are trained to live and fight in harsh environments will determine their unit's success or failure. “Jungle fighting is not new to US soldiers, nor does the enemy have a monopoly on jungle know-how. US units adapted well to jungle fighting, and when we operated against the North Vietnamese Army along the Cambodian border we found that they had as much difficulty operating in the area as we did. The prisoners we captured were, as a rule, undernour- ished, emaciated, and sick with malaria. They stated that almost everyone in their unit had malaria, and many had died from it.” Report, 25th Infantry Division, Republic of Vietnam jungle must learn that the most important thing is to keep their heads and calmly think out any situation. Many of the stories written about out-of- the-way jungle places were written by writers who went there in search of adventure rather than facts. Practically without exception, these authors exaggerated or invented many of the thrilling experiences they relate. These thrillers are often a product of the author’s imagination and are not facts. Most Americans, especially those raised in cities, are far removed from their pioneer ancestors, and have lost the knack of taking care of themselves under all conditions. It would be foolish to say that, without proper training, they would be in no danger if lost in the jungles of Southeast Asia, South America, or some Pacific island. On the other hand, they would be in just as much danger if lost in the mountains of western Pennsylvania or in other undeveloped regions of our own country. The only difference would be that a man is less likely to panic when he is lost in his homeland than when he is lost abroad. There is very little to fear from the jungle environment. Fear itself can be an enemy. Soldiers must be taught to control their fear of the jungle. A man overcome with fear is of little value in any situation. Soldiers in a CONTENTS SECTION PAGE I. General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 II. Jungle Hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 III. Jungle Survival . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10 2-1 –FM 90-5 Section II. JUNGLE HAZARDS EFFECT OF CLIMATE The discomforts of tropical climates are often exaggerated, but it is true that the heat is more persistent. In regions where the air contains a lot of moisture, the effect of the heat may seem worse than the same temperature in a dry climate. Many people experienced in jungle operations feel that the heat and discomfort in some US cities in the summertime are worse than the climate in the jungle. Strange as it may seem, there may be more suffering from cold in the tropics than from the heat. Of course, very low temperatures do not occur, but chilly days and nights are common. In some jungles, in winter months, the nights are cold enough to require a wool blanket or poncho liner for sleeping. Rainfall in many parts of the tropics is much greater than that in most areas of the temperate zones. Tropical downpours usually are followed by clear skies, and in most places the rains are predictable at certain times of the day. Except in those areas where rainfall may be continuous during the rainy season, there are not many days when the sun does not shine part of the time. People who live in the tropics usually plan their activities so that they are able to stay under shelter during the rainy and hotter portions of the day. After becoming used to it, most tropical dwellers prefer the constant climate of the torrid zones to the frequent weather changes in colder climates. INSECTS Malaria-carrying mosquitoes are probably the most harmful of the tropical insects. Soldiers can contract malaria if proper precautions are not taken. 2-2 FM 90-5- Mosquitoes are most prevalent early at night and just before dawn. Soldiers must be especially cautious at these times. Malaria is more common in populated areas than in uninhabited jungle, so soldiers must also be especially cautious when operating around villages. Mud packs applied to mosquito bites offer some relief from itching. Wasps and bees may be common in some places, but they will rarely attack unless their nests are disturbed. When a nest is disturbed, the troops must leave the area and reassem- ble at the last rally point. In case of stings, mud packs are helpful. In some areas, there are tiny bees, called sweatbees, which may collect on exposed parts of the body during dry weather, especially if the body is sweating freely. They are annoying but stingless and will leave when sweating has completely stopped, or they may be scraped off with the hand. The larger centipedes and scorpions can inflict stings which are painful but not fatal. They like dark places, so it is always advisable to shake out blankets before sleeping at night, and to make sure before dressing that they are not hidden in clothing or shoes. Spiders are commonly found in the jungle. Their bites may be painful, but are rarely serious. Ants can be dangerous to injured men lying on the ground and unable to move. Wounded soldiers should be placed in an area free of ants. In Southeast Asian jungles, the rice- borer moth of the lowlands collects around lights in great numbers during certain seasons. It is a small, plain-colored moth with a pair of tiny black spots on the wings. It should never be brushed off roughly, as the small barbed hairs of its body may be ground into the skin. This causes a sore, much like a burn, that often takes weeks to heal. LEECHES Leeches are common in many jungle areas, particularly throughout most of the Southwest Pacific, Southeast Asia, and the Malay Peninsula. They are found in swampy areas, streams, and moist jungle country. They are not poisonous, but their bites may become infected if not cared for properly. The small wound that they cause may provide a point of entry for the germs which cause tropical ulcers or “jungle sores.” Soldiers operating in the jungle should watch for leeches on the body and brush them off before they have had time to bite. When they have taken hold, they should not be pulled off forcibly because part of the leech may remain in the skin. Leeches will release themselves if touched with insect repellent, a moist piece of tobacco, the burning end of a cigarette, a coal from a fire, or a few drops of alcohol. Straps wrapped around the lower part of the legs (“leech straps”) will prevent leeches from crawling up the legs and into the crotch area. Trousers should be securely tucked into the boots. 2-3 — FM 90-5 SNAKES A soldier in the jungle probably will see very few snakes. When he does see one, the snake most likely will be making every effort to escape. If a soldier should accidently step on a snake or otherwise disturb a snake, it will probably attempt to bite. The chances of this happening to soldiers traveling along trails or waterways are remote if soldiers are alert and careful. Most jungle areas pose less of a snakebite danger than do the uninhabited areas of New Mexico, Florida, or Texas. This does not mean that soldiers should be careless about the possibility of snakebites, but ordinary precautions against them are enough. Soldiers should be particularly watchful when clearing ground. Treat all snakebites as poisonous. 2-4 FM 90-5—– 2-5 –FM 90-5 CROCODILES AND CAYMANS Crocodiles and caymans are meat-eating share of crocodiles, but there are few reptiles which live in tropical areas. authenticated cases of crocodiles actually “Crocodile-infested rivers and swamps” is a attacking humans. Caymans, found in South catch-phrase often found in stories about the and Central America, are not likely to attack tropics. Asian jungles certainly have their unless provoked. WILD ANIMAL In Africa, where lions, leopards, and other flesh-eating animals abound, they are protected from hunters by local laws and live on large preserves. In areas where the beasts are not protected, they are shy and seldom seen. When encountered, they will attempt to escape. All large animals can be dangerous if cornered or suddenly startled at close quarters. This is especially true of females with young. In the jungles of Sumatra, Bali, Borneo, Southeast Asia, and Burma there are tigers, leopards, elephants, and buffalo. Latin America’s jungles have the jaguar. Ordinarily, these will not attack a man unless they are cornered or wounded. Certain jungle animals, such as water buffalo and elephants, have been domes- ticated by the local people. Soldiers should also avoid these animals. They may appear tame, but this tameness extends only to people the animals are familar with. POISONOUS VEGETATION Another area of danger is that of poisonous plants and trees. For example, nettles, particularly tree nettles, are one of the dangerous items of vegetation. These nettles have a severe stinging that will quickly educate the victim to recognize the plant. There are ringas trees in Malaysia which affect some people in much the same way as poison oak. The poison ivy and poison sumac of the continental US can cause many of the same type troubles that may be experienced in the jungle. The danger from poisonous plants in the woods of the US eastern seaboard is similar to that of the 2 - 6 FM 90-5— tropics. Thorny thickets, such as rattan, should be avoided as one would avoid a blackberry patch. Some of the dangers associated with poisonous vegetation can be avoided by keeping sleeves down and wearing gloves when practical. HEALTH AND HYGIENE The climate in tropical areas and the absence of sanitation facilities increase the chance that soldiers may contract a disease. Disease is fought with good sanitation practices and preventive medicine. In past wars, diseases accounted for a significantly high percentage of casualties. WATERBORNE DISEASES Water is vital in the jungle and is usually easy to find. However, water from natural sources should be considered contaminated. Water purification procedures must be taught to all soldiers. Germs of serious diseases, like dysentery, are found in impure water. Other waterborne diseases, such as blood fluke, are caused by exposure of an open sore to impure water. Soldiers can prevent waterborne diseases by: Obtaining drinking water from approved engineer water points. Using rainwater; however, rainwater should be collected after it has been raining at least 15 to 30 minutes. This lessens the chances of impurity being washed from the jungle canopy into the water container. Even then the water should be purified. Insuring that all drinking water is purified. Not swimming or bathing in untreated water. Keeping the body fully clothed when crossing water obstacles. FUNGUS DISEASES These diseases are caused by poor personal health practices. The jungle environment promotes fungus and bacterial diseases of the skin and warm water immersion skin diseases. Bacteria and fungi are tiny plants which multiply fast under the hot, moist conditions of the jungle. Sweat- soaked skin invites fungus attack. The 2 - 7