Armor In Closed Terrain - U. S. Army Experience In Vietnam

[David]

Armor In Closed Terrain - U. S. Army Experience In Vietnam



CSC 1985 SUBJECT AREA Warfighting EXECUTIVE SUMMARY

Title: Armor in Closed Terrain -

U. S. Army Experience in Vietnam I. Purpose: To establish the combat role of armor in close terrain operations by using U.S. Army experience in Vietnam.

II. Problem: In spite of the various spectacular victory achieved by armor in closed terrain operations during Second World War, Korean War and Vietnam War, the general military perception has been that the combat guidelines for armor mobility, firepower, protection and chock effect can only be exploited effectively in an ideal terrain of open, rolling country.

III. Data: The valuable experience on armor operation in closed terrain during the Second World War were shelved away and forgotten as soon as the war ended. Until 1966, the U.S. Army had no independent armored units deployed in Vietnam. The decision to deploy U.S. armored units to Vietnam was made only after a careful and exhaustive study done in 1966. Contrary to the impression of the U.S. Army planner, the study found that armored forces could operate effectively in Vietnam. Soon after armored forces arrived in early 1967, they proved to the critics that their mobility, firepower, and protection could play an effective combat role in Vietnam. As a result armor played a pivotal role in Vietnam. In the final offensive mounted against South Vietnam, North Vietnamese Army has proved beyond doubts that armor was not out of place in close terrain.

IV. Conclusions: The U.S. Army experience in Vietnam indicated that many military professionals have over estimated the difficulties of closed terrain. Armor in Vietnam has proved beyond doubts that, with thorough planning and imaginative employment, armored forces can play a useful combat role in close terrain.

V. Recommendations: The U.S. Army must acquire and expand a capability for operating in close terrain. This capability could be acquired now by re- examining and analyzing tactics and techniques employed by armor in Vietnam. The equipment modifications and innovations that were achieved in Vietnam should be further evaluated and documented. The lesson learned should be transformed into relevant doctrines. Armor in Closed Terrain: U.S. Army Experience in Vietnam On 13 May 1940, seven Panzer divisions swept through the Ardennes forest, hitherto considered by France and other Allies as an impossible physical barrier, brushed aside the light infantry resistance and dashed westward into the French plains. The strategic surprise achieved was so great that by 5 June, France had capitalized along with Belgium and Holland, while the British ally fled back across the channel. This spectacular victory was achieved through the imaginative use of armored forces by the German High Command which accomplished within a few weeks what the Germans had failed to do in four years of bitter fighting in the First World War.

1 Although this unexpected and unorthodox use of armor in closed terrain caused much confusion amongst the Allies, this lesson was largely forgotten as soon as the war was over. Instead, it was the magnificent armor battles in North Africa and in the rolling plains of Western Europe that captured the imagination of most military men. Since then, the general military perception has been that the combat qualities of armor mobility, firepower, protection and shock effect can only be exploited effectively in an ideal terrain of open, rolling country.

2 Unfortunately, the greater part of the world does not enjoy the advantage of such ideal terrain to exploit the combat qualities of the tank. So, a doctrinal question must be answered: Can armored forces play a useful combat role in close terrain? This paper will attempt to determine the feasibility by examining U.S. experience in Vietnam. But, before one can discuss the potential role of armor in closed terrain, one must understand that, notwithstanding inherent combat values, the tank has definite limitations too.

A glimpse at the technical characteristics of a typical Main Battle Tank (MBT) will reveal the inherent weaknesses of this kind of weapon. For example, the U.S. M-60 medium tank has a vertical climbing ability of only 36 inches, a ditch crossing capability of 102 inches and a fording depth of 48 inches. As for slope ascending ability, it can climb a gradient of no more than 60 percent or traverse of side slope of no more than 30 percent.

3 Faced with so many limitations, it is not illogical to conclude that the tank is only useful in an ideal terrain, with few or no obstacles to impede its mobility and degrade its shock effect. Terrain should also afford far reaching and uninterrupted visibility so that the tank can exploit its long-range firepower and at the same time, protect itself against possible anti-tank ambushes. From the foregoing, one might conclude that the tank is not built for the closed terrain. In conventional military usage, closed terrain is defined as an environment of poor visibility and traffic ability such as that found in jungles, hilly and mountainous terrain, or in built-up areas. In the jungle, the terrain is usually rugged, covered with dense, multiple-canopied trees and impenetrable undergrowth, and criss-crossed by numerous rivers and streams. In such an environment, visibility is inevitably limited and movement is near impossible, even for infantry. As for armor, the use of its weaponry is greatly constrained, while vulnerability to anti-tank ambushes is ever present. Thus, it is no surprise that the jungle has been regarded by military men as a barrier to be avoided by armor.

4 Isolated experience in World War II had shown that armor, when employed judiciously, can play a useful combat role even in closed terrain. This was amply demonstrated in the decisive use of armor twice by the Germans in the Ardennes forest, again in the marshy bogland of the Kurst by the Russians; and in the humid forests of Burma and Malaysia by the British and Japanese respectively. Even the U.S. Army made significant use of tanks in the rugged mountains of Sicily and Italy, and in the steaming jungles of the Pacific Islands.

5 But, as soon as the war ended, these valuable experiences were shelved away and forgotten.

A case in point is to be found in the 1957 U. S. Army FM17-1 - Armor Operations, Small Units

6 and the 1961 FM17-30 - Armor Division Operations

7 which reveals that no more than a few brief paragraphs have been devoted to combat in mountains, woods, and jungle areas. Obviously, there has been a singular lack of U.S. doctrine for mechanized warfare in areas other than the Middle East and Europe.

8 In the light of this inadequacy, the U.S. Army was compelled to relive the painful experience of learning how to use armor in the closed terrain of Vietnam. The closed terrain of South Vietnam presented a variety of problems, ranging from mountains to jungles and paddy fields. The relief divides the country into four distinct terrain types: the mountains, central plateau, coastal plains and the delta. The mountains, which constitute two-thirds of South Vietnam, are rugged and jungle covered. They are criss-crossed by numerous streams and rivers. Land communications are virtually impossible except for a few inferior roads and trails that can be used only in the dry season. The central plateau extends along the entire Cambodian border and is covered with either thick forests or tall Savannah grass.

This terrain is equally unsuitable for vehicular movement. The coastal plains, although highly trafficable, are discontinuous and segmented by mountain spurs and hills that reach out to the sea. The delta is a vast, utterly flat region of paddy fields traversed by few roads and criss-crossed by a dense network of deep, steep-banked canals and broad tidal rivers. The coast line and rivers are usually lined with mangrove swamps. Traffic ability, while affected most significantly by land-forms, is also influenced by weather. Vietnam has two distinct seasons. The Southwest Monsoon, beginning in April and running to September, brings heavy rainfall to the mountains and to the south and southwest. The Northeast Monsoon, lasting from October to March, brings heavy rains to the northwest coast. One might easily conclude from the foregoing brief review that South Vietnam, is scarcely to be regarded as an armor-country. According to General Donn A. Starry, it was this impression that led the U.S. Army planners to conclude that there was no combat role for armored forces in Vietnam.

9 Apart from terrain and weather considerations, there were several other reasons that led U.S. Army planners to conclude in the early 1960's that the war in Vietnam would be on infantry and special forces fight. The most important reason was that the valuable experience learned so painfully in the closed terrain of Korea has been shelved away and forgotten. It was not surprising that up to the 1960's, there was a singular lack of doctrine for mechanized combat in areas other than Europe and the Deserts of the Middle East. Take for example, the 1960 Field Manual FM17-30 - Armor Division Operations which devoted only one brief, 14-line paragraph to combat in closed terrain. Another reason could be traced to the unsuccessful experience of the French armored forces in Indochina, which reinforced U. S. military opinion that there was no place for armor in Vietnam.

10 The last reason was that U.S. Army planners felt that armored forces would not be able to cope with the elusive "guerilla enemy" in a counterinsurgency setting. Moreover, the emergence of the air mobile concept during this period was thought to be the panacea to the counterinsurgency problem. Thus, Army planners saw little or no need for armored unit in the initial U.S. force structure in Vietnam.

11 Until 1966, the U.S. Army had no independent armored units deployed in Vietnam. Those units that operated there were the organic armored elements of U. S. infantry and Marine divisions, or independent infantry brigades. These consisted of one Marine tank battalion, four divisional armored Calvary squadrons, four brigade armored cavalry squadrons, and seven mechanized infantry battalions.

12 It was clear that these armored units were not deployed to Vietnam through deliberate planning, but found their way there as organic parts of their parent divisions or brigades. Nevertheless, their presence enabled a pattern for mechanized infantry and armor operations to emerge, and this was to blaze a trail for a dramatic increase in the deployment of armored forces to Vietnam after 1967. The decision to deploy U.S. armored units to Vietnam was made only after a careful and exhaustive study. In late 1966, the Chief of Staff directed the Department of Army to determine whether mechanized infantry and armor operations would be feasible in Vietnam.

13 This led to a study entitled, "Evaluation of U.S. Army Mechanized and Armor Combat Operations in Vietnam", MACOV in brief. The study, under the direction of Major General Arthur L. West, Jr., was conducted between 6 January to 28 March 1967 by a team of 99 military and civilian analysts.

14 The team evaluated 18,000 questionnaires which were sent to infantry, mechanized infantry and armor officers, and NCO's stationed in Vietnam. The military team members not only conducted field observations, but also participated physically in operations undertaken by armored units organic to the infantry and Marine divisions or independent infantry brigades. The team also analyzed over 2,000 Headquarters Reports, Unit After Action Reports and Embassy files, and interviewed many commanders and staff officers. All these data were than analyzed in relation to the terrain and prevailing weather in Vietnam. The findings of the MACOV Study were revealing. Contrary to the impression of the U.S. Army planners, the study found that armored forces could operate effectively in Vietnam. The experience of the organic armored elements showed that armor, with its inherent combat qualities of mobility, firepower and protection, could be a useful component of the combined arms concept used widely in Vietnam.

15 The study also found that armored units suffered far fewer and less casualties than the infantry. For example, 59 percent of armor personnel casualties could return to duty within a week in comparison to 22 percent of the infantry casualties. More importantly, the MACOV study concluded that tanks, with organic support, could move in 61 percent of Vietnam during the dry season and 46 percent during the wet season. Armored personnel carriers could move in 65 percent of the country all the year round. Perhaps, what was more important was that the results of the study provided the overriding rationale for the U.S. Joint Chiefs of Staff to sanction the deployment of armored forces to Vietnam.

16 The official deployment of U.S. armored forces to Vietnam commenced in late 1967. By 1973 the list of armored forces included four tank battalions, one mechanized brigade, one armored Calvary regiment, ten mechanized infantry battalions, and eight armored Calvary regiments. These units made up 46 percent of the total U.S. combat forces in Vietnam. The armor equipment used in Vietnam came from the conventional inventory of the U.S. Army and was not modified for use in this theatre. The tank battalions were all equipped with the M48A3, a medium tank. The only light tank possessed by the U.S. armor in the Vietnam era was the M-551 Sheridan tank. The M-551 was withdrawn from the Vietnam theatre after a six-month trial revealed that it had numerous technical shortcomings which could not be rectified.

17 The main armored fighting vehicles used by the mechanized infantry battalions and the armored Calvary squadrons were the M113A1 Armored Personnel Carrier (APC), the M132 Flame Thrower, and the M125 81mm Mortar Carrier. All this equipment, although not specifically modified, was able to support the users with great effectiveness. No sooner had they arrived in early 1967, than the newly deployed armored forces proved to the critics that their mobility, firepower, and protection could play an effective combat role in Vietnam. This was clearly evident in the series of multi-divisional operations conducted between January and April 1967. The most notable of these were Operation Cedar Falls and Operation Junction City, which were major search and destroy actions conducted around Saigon in the III Corps Tactical Zone (CTZ III).

18 In search and destroy operations, armored units were usually employed as fixing (cordon) and reaction forces so that their mobility and firepower could be exploited to the best advantage. These characteristics also enabled mechanized units to control twice as much terrain as conventional infantry battalions.

19 The combat effectiveness of armor can best be illustrated by the combat at Fire Base Gold near Suoi Tre, 85 miles northwest of Saigon. This was one of the three major battles fought in Operation Junction City. On 21 March 1967, 2nd Battalion, 34th Armor and 2nd Battalion, 22 Infantry Mechanized were participating in a search and destroy operation when they were ordered to reinforced Fire Base Gold, which had come under attack by a large force of Viet Cong (VC's) at first light.

20 The fire base was defended by one U.S. infantry battalion and one artillery battalion. By 0700 hours, parts of defense perimeter had been breached and ammunition was running low!

21 At this juncture, a glimpse of the organization of the two armored battalions would enable one to understand better how armor could make a difference in this critical situation. The two battalions, like all other armored elements, possessed tremendous organic firepower and mobility. A mechanized infantry battalion had a strength of 758 personnel mounted on 82 APC's. The APC's were armed with 107 0.5 inch and 172 7.62mm machine guns, and 12 81mm self-propelled mortars. The troops, apart, from their personnel M-16 rifles, were equipped with 188 40mm grenade launchers.

22 The tank battalion had 68 M4FAB's, each equipped with one 90mm cannon, one 0.5 inch and two 7.62mm machine guns, and one 40mm rocket launcher.

23 This bristling firepower and organic mobility proved to be a valuable combat asset in Vietnam. While racing to the beleaguered fire base, the two battalions had to bash through five kilometers of jungle and ford the Suoi Samat River. For these tasks, a helicopter helped in the navigation and selection of a suitable crossing site, and the medium tanks were used to smash through the jungle.

24 While enroute, the battalions also brushed aside two hastily-set VC ambushes. They arrived just in time to save the embattled base as the VC's were within five meters of the battalion aid station and within hand grenade range of the combat post. Into this chaos came 68 medium tanks and 82 APC's, crushing through the last few trees into the clearing surrounding the base. Upon reaching the base, the lead tanks and APC's opened up with their cannons, machine guns and rocket launchers. The shock effect was overwhelming, especially when the attacking VC's were caught in the open. The ground shook as the tanks and APC's maneuvered around the perimeter of the beleaguered base firing into the ranks of the attacking enemies and crushing many of them under their tracks. The VC's realizing that they could not outrun or outgun the armored vehicles, charged at them and even attempted to climb on board. But, they were cut down by the deadly machine gun fire. The VC's lost more than 600 men in this action.

25 LtCol John A. Bender, the Fire Base Commander, described it, "just like the late show on T.V., the U.S. cavalry came charging to the rescue."

26 The armored forces, as in many other set piece battles in Vietnam, had turned the tide at Fire Base Gold. Their inherent flexibility enabled them to be switched from one mission to another with the minimum of time and fuss. In fact, a new mission could be planned by the commanders and others delivered to the troops through the intercommunication system, all done while on the move to the new destination. Their mobility enabled them to bash through the jungles and reach the beleaguered base in time. Their firepower and armored protection enabled them to deliver deadly blows to the attacking VC's without suffering the high casualty rates of conventional infantry. The combat effectiveness the armored forces demonstrated at Fire Base Gold was only one of the many battles that armor played a pivotal role, both in Operation Cedar Falls and Junction City, and throughout the Vietnam conflict. That the combat qualities of armored forces could be exploited with such effectiveness in the closed terrain of Vietnam had to do with their ability to adapt to the various terrain constraints. Within a year of their arrival in Vietnam, the armored forces had found a useful niche in the U.S. strategy of search and destroy and also demonstrated that they were quick to adapt to the terrain constraints. Not surprisingly, the Commander, U. S. Army Vietnam emphasized in his 1967 Vietnam Report that, "Tanks, APC's, self-propelled artillery and other tracked vehicles are being employed with increasing success in regions formerly thought alien to armored units.... Warfare in Vietnam is oriented to the enemy rather than to terrain, therefore shock effect and heavy firepower become most important."

27 Contrary to general impressions, the jungle was not impenetrable or insurmountable. This became more evident in the aftermath of the 1968 Tet Offensive, when both sides changed strategy. The NVA and VC's, after having lost more than 60,000 trained troops in the recent Tet Offensive, were forced to retreat into the border and jungle sanctuaries to lick its wound. The new Commander of the U.S. Army in Vietnam, General Creighton W. Abrams, decided to pursue the enemy into these sanctuaries to keep up the pressure on them.

28 Armored units, with their inherent mobility and firepower would now spend most of their time in the bush or jungle rooting out the NVA and VC's. A telling example was Operation Montana Raider. This was a reconnaissance-in-force, located near the Cambodian border. The regiment, with 250 tracked vehicles, combed no less than 1,600 kilometers from 13 April to 13 May 19698. Of that distance, 1,300 kilometers were in dense jungles.

29 For movement in these jungles, tanks were used to break paths through the thick vegetation for other vehicles. Where tanks encountered difficulties, the Combat Engineer Vehicle (CEV), was used to blaze a trail. Navigation in the jungles was made easier with the aid of vehicle-mounted compass, designed by the U.S. Army Material Command in Vietnam.

30 When terrain obstacles interfered with navigation, helicopters were used to guide tracked vehicles along the lines of least resistance or to locate suitable river crossing sites. To enable tracked vehicles to cross the numerous streams and other natural obstacles, the M113 AVLB's were used with great success, thus greatly enhancing the mobility of tracked vehicles in closed terrain. Apart from providing tactical mobility, tanks and APC's also proved to be extremely useful against booby traps and anti-personnel mines that were randomly found in the jungles. As armored vehicles were extremely vulnerable to anti-tank weapons in closed terrain, "RPG Screens" were used during night laagers to protect armored vehicles from anti-tank chemical rounds. The RPG screen was another field innovation in Vietnam that was no more than a strip of cyclone fence. When erected around vehicles, it would detonate any chemical rounds before they hit the targets.

31 Operation Montana was not the only armor operation in the jungle. Throughout the Vietnam conflict, armored forces had, either independently or combined with the infantry, conducted numerous successful search and destroy operations in the jungles of CTZ's I and III or in the tall Savannah grass along the Cambodian border. In fact, 75 percent of the missions for armored forces were on search and destroy operations.

32 That mechanized forces could operate in the jungle was due largely to their ability to improvise equipment and techniques in overcoming terrain difficulties. Although U.S. armored forces played a pivotal role in the Allied Strategy in Vietnam, ironically, it was the NVA that finally proved beyond any doubts that armor was not out of place in closed terrain. In the final offensive mounted against South Vietnam in April 1975, the NVA skillfully exploited the combat advantages of armor to provide the colorful ending to the last chapter of the Vietnam War. The NVA employed fully integrated combined arms attack formations. These consisted of a nucleus of armor and infantry, with artillery, mobile anti-aircraft and engineers in close support. The attack formations, organized in echelons and well-drilled in "sudden assault" and "deep advance", were used by NVA with spectacular success. For example, in the Tay Nguyen Battles near Saigon, infantry were used in diversion battles on Routes 19 and 21, while tanks and armored forces were concentrated for the next battle at Ban Me Thout.

Another example was the final assault on Saigon, in which infantry, supported by tanks, assaulted the outer defenses in the outskirts of the city, while tanks and armored forces were sent 40-50 kilometers into the heart of the capital to seize the enemy's most critical military and political targets. All this was possible only because great emphasis was given to the mobility of the armored battle groups by the NVA. All NVA advance columns were well supported by engineer forces whose task was to ensure favorable traffic ability. They would move ahead to secure and strengthen bridges, organize staging areas, remove mines, repair bridges, and overcome obstacles. Improvisations and use of local resources were widely practiced with much imaginative planning, thorough preparations, and aggressive execution. The NVA's advance was reported to have averaged 50-60 kilometers per day.

By 30 April 1975, the T-54's rolled into Saigon and South Vietnam ceased to exist as a nation with the fate of the Vietnam War now decided, it would be appropriate to conclude the experience of the U.S. armored forces in Vietnam. When armor arrived in Vietnam in early 1967, they proved to the critics that the jungle was no barrier to their mobility, and that their firepower and protection could play a useful role in the U. S. strategy and tactics employed in Vietnam. Following this initial demonstration of effectiveness, armor participated either independently or in conjunction with air mobile and conventional infantry forces, in almost every major operation from the humid jungles to the inundated delta and to the concrete jungles of the built-up areas. Armor's protection, firepower, and ability to react quickly prevented many certain defeats and brushed aside many ambushes with ease. Their inherent flexibility, coupled with an ability for sustained actions, enabled units from a typical mechanized battalion to fight up to three or more critical battles simultaneously at widely separated locations. That mechanized forces could operate effectively in the closed terrain of Vietnam was largely due to their ability to improvise equipment and techniques in overcoming terrain difficulties.

In the absence of any specifically tailored equipment and appropriate doctrine, the U. S. armor personnel resorted to imagination and resourcefulness. They adapted quickly and soon improvised and innovated many useful devices and techniques. Prominent among such innovations were the AVLB's for crossing of obstacles, use of helicopters and APC-mounted compasses for navigation in closed terrain and RPG screens against anti-tank weapons.

Many, if not most of these innovations and improvisions were evaluated by the field users in Vietnam. In retrospect, they went a long way in enhancing the mobility of armored forces in closed terrain. But, this was not achieved without heartbreaks and trials. In summing up, the U.S. Army experience in Vietnam indicated that many military professionals have over-estimated the difficulties of closed terrain. This unnecessary fear caused the initial absence of armor. But, as soon as armor arrived, it found a useful niche, and as the wars progressed, armor began to play a pivotal role. While it is true that armor alone could not have won the wars, it provided the badly needed close support to the infantry and constituted an essential component of all combined arms teams or task forces. In Vietnam, armored forces were able to overcome most of the terrain difficulties through improvisions and thus could play a greater pivotal role. They could even operate independently throughout Vietnam, whether in the jungle or in the unundated delta.

While it is true that armor could operate quite effectively in closed terrain of Vietnam, experience shows that there are some practical limits to which armor can be used in such terrain. Although mechanized forces could move with reasonable freedom in Vietnam, there were practical limits. For example, the mountainous jungles would certainly be off limits to armor. The less undulating jungle can only be traversed if tracked vehicles follow the lines of least resistance. For this, they need to be guided by helicopter. To be sure, armor will not be along in being confronted with such insurmountable terrains. These terrains are equally untrafficable to the infantry, air mobile units, and artillery. The latter particularly requires favorable terrain for mobility and deployment. Apart from these practical limits, the major lesson to be learned from this study is that the U.S. Army has, to its detriment, paid far too little attention to armored operations in Vietnam.

Strategic and doctrinal thinking of the U.S. Army has, since World War II, been fixed with the open, rolling fields of her Allies in NATO. It is, therefore, not surprising that the U.S. Army has more or less consistently ignored the experience gained by armor in closed terrain. The few but successful examples from World War II were ignored after that conflict. Fortunately, the U. S. Army was flexible enough to adapt to the demanding environment in Vietnam. The next war in which the U. S. Army is required to get involved in is likely to be in the Third World, and again, most likely with a closed terrain. If the U.S. armor is to avoid the painful experience of re-learning how to use armor in closed terrain, it might be worth the while to prepare now. For an army that boasts of global responsibilities no aspect has been more neglected. Since the U.S. Army's main theatre of operation is in NATO, its organization and doctrines should rightfully be geared primarily toward this theatre. There is no need for any drastic institutional or organizational changes within the U. S. Army.

The U.S. Army must however, have the ability to acquire immediately and expand quickly a capability for operating in closed terrain. This capability could be acquired now by re-examining and analyzing all the tactics and techniques that were employed by the armored forces in Vietnam, and the fire support and logistics systems that were used in the various types of closed terrain. Additionally, the equipment modifications and innovations that were achieved in the field in Vietnam should be further evaluated and documented. The synthesis of all these experiences and lessons should be transformed into relevant doctrines or recommendations on equipment modifications that are necessary for the various types of closed terrain. After all, U. S. Army experience in Vietnam has shown beyond any doubt that, with thorough planning and imaginative employment, armored forces can play a useful combat role in closed terrain.