Infantry, Part I: Regular Army /The War in Vietnam

by John K. Mahon and Romana Danysh

• The War in Vietnam

• The first U.S. infantry combat units arrived in Vietnam in May 1965. They were the 1st and 2nd Battalions, 503rd Infantry, elements of the 173rd Airborne Brigade, previously stationed on Okinawa. These units were joined in July by three battalions from the 1st Infantry Division and three battalions from the 101st Airborne Division, and in September by eight battalions of the 1st Cavalry Division (Airmobile). The infantry battalions organic to the 173rd Airborne Brigade and the 101st Airborne Division were airborne, those assigned to the 1st Infantry Division were standard infantry, while the elements of the 1st Cavalry Division were a new type of unit called "airmobile." Although the airmobile infantry battalions had no organic aircraft, the division was authorized 428 helicopters, enough to give all of its elements tactical mobility by air.

• Military strategists had long dreamed of airmobile units that would introduce a true third dimension to the battlefield. The first practical application of the airmobile concept, the organization of the 11th Air Assault Division, was made possible by the great strides of recent years in the design, production, and doctrine of employment of the helicopter Elements of this test division were activated at Fort Benning, Georgia, starting in February 1963 as a result of the recommendations of the U.S. Army Tactical Mobility Requirement Board, more commonly known as the Howze Board after its chairman, Lt. Gen. Hamilton H. Howze. Following more than two years of testing and evaluation, the Secretary of Defense approved the creation of a combat ready airmobile division. The 1st Cavalry Division was selected. It was transferred less personnel and equipment from Korea to Fort Benning and was reorganized as airmobile on 1 July 1965. With the formation of this division the Army acquired a new way of bringing the infantry and other ground troops in contact with the enemy. One of the major goals of the ROAD reorganization had been to furnish appropriate tactical mobility to combat units in different geographical areas. The development of airmobile units was another example of ROAD's continuing flexibility. Since in Vietnam the use of ground vehicles was severely limited by terrain, the new airmobile division was ideally suited for employment there.

• Probably the most significant innovation of the war was the largescale use of helicopters in general and of airmobile combat units in particular. All units in Vietnam depended heavily on the helicopter for aerial reconnaissance, medical evacuation, and resupply, as well as rapid transportation into and out of otherwise inaccessible areas. Helicopters used by the infantry were Army not Air Force aircraft and, as such, were more responsive to the needs of the units. The infantry in turn quickly adjusted to airmobile operations. Although all types of infantry units were regularly transported by helicopter, the airmobile division was the only infantry organization that could move all of its elements with its own organic aircraft.

• Airmobile units were capable of moving rapidly and directly to their objective regardless of terrain obstacles or enemy troop concentrations. Responding swiftly to changes in the tactical situation, they could break off action at one point and fly quickly in any direction to fight at another point or disperse to widely separated bases. Characterized by speed, surprise, maneuverability, and aggressiveness, the airmobile assault proved to be a highly successful offensive technique. In terrain such as that of Southeast Asia, it was a great improvement over airborne assault techniques developed in World War II. Except for one jump by elements of the 173rd Airborne Brigade on 22 February 1967, no combat parachute drops were made by U.S. Army units in Vietnam, whereas literally thousands of helicopter missions took place. On 1 July 1968, therefore, the 101st Airborne Division was reorganized as airmobile. Although the division base was significantly changed in the process of airmobilization, this was not a major reorganization for the ten airborne infantry battalions assigned to the division. By that time their structure had already been standardized under Modification Tables of Organization and Equipment (MTOE's) for light infantry battalions.

• When the buildup of U.S. troops in Vietnam began in 1965, infantry units in general were organized under the ROAD tables of 15 July and 15 August 1963. Shortly thereafter a new series of infantry TOE's was published. These tables were prepared under the direction of the U.S. Army Combat Developments Command, which had been created during the 1962 reorganization of the Department of the Army. The new command took over the responsibility for development and processing of TOE's from the Continental Army Command (CONARC), but training of infantry units and supervision of the Infantry School remained CONARC functions. The standard and mechanized infantry tables were dated 31 March 1966, while the airborne infantry had two sets of tables, dated 30 June 1965 and 30 June 1966. These TOE's added an air defense section to the headquarters company of all three types of battalions, which was organized to use the new Redeye guided missile system (a manportable, shoulder-fired, low altitude, antiaircraft weapon). The Davy Crockett section augmentation was eliminated from the battalions, but in February 1967 a tentative test TOE for a separate infantry Davy Crockett platoon was published. Its primary mission was to provide close-in nuclear fire support for the maneuver battalions of a division or brigade. Since this was a test TOE, units were to be organized under it only when specifically directed.

• The number of personnel in airborne units was reduced by the 1965 and 1966 TOE's, and lighter equipment was authorized for them. The battalion's antitank weapon was changed from the ENTAC to the 106-mm. recoilless rifle, which in turn was to be replaced by the TOW (Tube-launched, Optically-tracked, Wireguided) missile system as soon as it became available. A new individual rifle, the lightweight M16, was also authorized for airborne infantrymen. All three types of infantry battalions-standard, mechanized, and airborne-retained the ROAD structure of a headquarters and headquarters company and three rifle companies.

• Meanwhile, test TOE's had been prepared by the Combat Developments Command for two new types of infantry units, the airmobile battalion organic to the airmobile division and a special infantry battalion which was to be assigned to light infantry divisions and separate light infantry brigades. With authorized strengths of 767 and 769, respectively, these units were smaller than the regular infantry battalion of 849 men Both battalions had a headquarters and headquarters company, three rifle companies, and a combat support company consisting of a mortar platoon equipped with 81-mm. mortars, a reconnaissance platoon, and an antitank platoon armed with 106-mm. recoilless rifles. The rifle companies in both battalions had three rifle platoons supported by an 81-mm. mortar platoon, and the rifle squads consisted of ten men. The basic individual weapon in the light infantry battalion was the M14 rifle, while the airmobile unit was authorized M16 rifles. The new battalions had fewer telephones and radios than other infantry units and the number of vehicles, particularly in the airmobile battalion, was considerably smaller than in the standard infantry battalion.

• Regular infantry units, serving in Vietnam did not use all of their authorized heavy weapons and equipment. As a rule, most of their vehicles and weapons like ENTAC's, 4.2-inch mortars, and 106-mm. recoilless rifles were left behind either in storage or in base camps while the units were in the field. Although 90mm. recoilless rifles and 81-mm. mortars were employed much more frequently than their more powerful and heavier counterparts, a rifle company rarely carried its full TOE complement of these weapons on operations and often used the much lighter LAW instead of the 90-mm. recoilless rifle. The resulting loss in firepower was offset by a corresponding gain in mobility and a decrease in fatigue among the soldiers. Transporting heavy equipment in most parts of Vietnam was a very difficult procedure, while excellent air and artillery support was readily available. Infantrymen, therefore, were not reluctant to leave some of their own fire support weapons behind. Since the enemy did not employ heavy armored forces, certain heavy weapons (notably the big antitank missiles and 106-mm. recoilless rifles) were used rarely or not at all, simply because they were not needed.

• Personnel who would normally man the heavier infantry weapons were frequently used to make up a small fourth rifle company within the battalion. This unit served as a command post security force and as an emergency reserve, thereby giving the, battalion commander three maneuver companies and additional flexibility in the employment of the battalion. Since this provisional extra company was so common, and it increased the capabilities of the battalion significantly, official permission was given to all infantry battalions in Vietnam to organize such units on a permanent basis. Battalions stationed elsewhere were not authorized the additional company. This variation from the basic TOE structure was approved by MTOE's prepared under the direction of the Commander in Chief, United States Army, Pacific. Such tables were published from time to time by the major Army commands to make appropriate changes for particular units necessary to meet certain requirements without altering the basic TOE for other units of the same type. Another change approved by MTOE's was the addition of a separate combat support company to standard and airborne infantry battalions. Only those battalions that were stationed in or scheduled to be deployed to Vietnam were permitted to have this extra company, which was similar to the one in airmobile and light infantry units.

• Gradually all infantry battalions in Vietnam, with the exception of mechanized and riverine units, were reorganized under modifications of the light infantry battalion TOE with a headquarters and headquarters company, four rifle companies, a combat support company, and a total authorized strength of 920. Eventually the organizational modifications adopted in Vietnam were also recommended as changes to the basic infantry TOE's. One suggestion was to remove the mortar, reconnaissance, and antitank platoons and the ground surveillance and air defense sections from the headquarters company of the infantry battalion and to organize them into a separate combat support company, leaving only the administrative and service support elements in the new headquarters company. Another suggestion was to authorize a fourth rifle company for the infantry battalion in wartime, but to retain the three-company structure in peacetime. By the, end of 1969 this recommendation was still under study by the Army Staff, but TOE's were already being prepared for the new headquarters and combat support companies.

• Although few mechanized infantry units were sent to Vietnam, those that served there operated effectively wherever the terrain permitted. They were equipped with M113 and M113A1 armored personnel carriers, which were sometimes employed as fighting vehicles in a tank-like role. The mechanized battalion was modified to include a smaller fourth rifle company, but a separate combat support company was not authorized. Mechanized infantry battalions located outside of Vietnam were organized with three rifle companies, as provided by the basic TOE.

• Units from the 9th Infantry Division, together with a Navy task force, created the Mobile Riverine Force which operated in the Mekong Deltaa low and flat region with innumerable canals, rivers, swamps, and inundated rice paddies, almost completely inaccessible to ground troops, especially during the long monsoon season. Riverine infantry units fought as regular infantry but lived on barrack ships and were transported by specially modified landing craft, known as armored troop carriers. They received fire support from Navy gunboats as well as from Army artillery mounted on barges.

• Since there were no clearly defined front lines and it was difficult to find and fix the enemy without running the risk of falling into an ambush, reconnaissance, intelligence, and patrolling became particularly important in Vietnam. Although all units took part in such operations, specialized infantry units were also organized to carry out certain types of missions. Among them were scout dog platoons and combat tracker teams-both of which used dogs to detect the presence of enemy troops-and long range reconnaissance patrols (LRRP's), also called long range patrols (LRP's) . LRP's were small teams specially trained to penetrate deep into enemy-held territory. From there they reported detailed, accurate, and timely information concerning troop concentrations, installations, and activities needed for planning future operations, or they called in and adjusted artillery fire or air strikes.

• Infantry long range patrol companies, having twenty-four patrols of five men each, were first assigned on the basis of one per corps or field force, while within divisions LRRP missions were performed by provisional detachments or platoons. Starting in late 1967, a LRP company was attached to each division in Vietnam and eventually to each separate brigade. The number of companies continued to increase and by the end of 1968 about half of all separate infantry companies in the active Army were long range patrol units. They were elements of various different regiments and had no common numerical designation or historical connection with each other until 1 January 1969. On that day the 75th Infantry, the famous "Merrill's Marauders" of World War II, was reorganized under CARS and became the parent regiment for LRP units. At the same time the parenthetical designation of the companies was changed from LRP to ranger, although their long range patrol mission remained unchanged.

• The importance of small units in Vietnam was not limited to such specialized organizations as long range patrols, scout dog platoons, combat tracker teams, or Special Forces detachments. Regular infantry contacts with the enemy were frequently made at the squad and platoon level. Small unit actions were typical and often decisive. As a result, the war in Vietnam has often been called a platoon leader's war. Most major operations were conducted on the brigade level with varying numbers of maneuver elements attached for specific missions in accordance with the ROAD principle of tailored brigades. Vietnam was the first test of the ROAD organization under actual combat conditions, and the system proved its flexibility by adapting quickly to a difficult terrain and an elusive enemy in a war with many unconventional aspects.

• The most popular infantry weapons in Vietnam were the lightest ones. Among them were the M79 grenade launcher, the LAW, and the Claymore antipersonnel mine. The mine, which scattered hundreds of steel fragments in a fan-shaped pattern, could be deliberately detonated by the operator or concealed and left to be activated by trip wire. As its official field manual stated, the number of ways in which the Claymore might be employed was limited only by the imagination of the user. Another widely used weapon was the. M60 machine gun.

• There was also the new M16 rifle. The rifle itself weighed 6.5 pounds and its firing weight, including a shoulder sling and a fully loaded 20-round magazine, was only 7.6 pounds. The M16 used 5.56-mm. (.223-caliber) ammunition. A clothespin-type bipod and a 6-inch bayonet were issued with the rifle. Having a muzzle velocity of approximately 3,150 feet per second and an average cyclic rate of fire of 750 rounds per minute, the M16 was particularly effective at short ranges. It was less accurate and less effective than the M14 at long ranges and, unlike the M14, did not fire standard NATO ammunition. However, its light weight and lethal close-in effectiveness made the M16 an ideal weapon in terrain such as Vietnam's. Although originally adopted for limited use by Special Forces and airborne troops, the M16 was soon authorized for all infantry units in Southeast Asia. In mid-1967 it was standardized for general Army distribution in addition to the M14 rifle, which continued to be used by most infantrymen stationed outside of Vietnam.

• Meanwhile, the manufacturers of the M16 were developing an entire family of 5.56-mm. weapons to supplement the M16 rifle. These included a carbine, a submachine gun, a, very light survival rifle, a heavy assault rifle, and several machine guns, as well as a 40-mm. grenade launcher attachment for the M16. By late 1968, the submachine gun was being authorized for selected infantry units, such as long range patrol companies and combat tracker platoons. A completely new kind of weapon called SPIW (Special Purpose Individual Weapon) was also in the process of development. The new SPIW may combine the capabilities of a rifle, a controlled pattern shotgun, and a light mortar. It could be designed to fire a single medium-sized dart, a cluster of small darts, a microcaliber bullet, or a high explosive round. Many military experts predicted that the SPIW, or something like it, would become the basic infantry weapon of the future. By the end of 1969, however, the SPIW was still purely experimental, and no such weapon was available to the infantryman fighting in Vietnam.

• Infantry strength in Vietnam had increased gradually as the war escalated. By mid1969, when the eleventh official campaign was being fought and just before the first phase in the withdrawal of U.S. troops began, there were seven divisions and four brigades in Vietnam. To make this large scale deployment possible without moving units from Europe and Korea or reducing the strategic reserve to a dangerously low level, the overall strength of the Army and the infantry had been built up. Between June 1964 and June 1969 the number of divisions in the active Army grew from sixteen to eighteen, while brigades increased from seven to eleven.

• Two of the brigades were federalized Army National Guard units, the 29th Infantry Brigade from Hawaii and the 69th Infantry Brigade from Kansas. They were ordered into active Federal service on 18 May 1968, as a result of the Pueblo crisis and the Tet offensive earlier that year. Only two of the three organic infantry battalions from the 69th were called up, but the 2nd Battalion, 133rd Infantry, from Iowa was also federalized and joined the brigade at Fort Carson, Colorado. At the same time the 100th Battalion, 442nd Infantry, a Hawaiian Army Reserve unit, was called to active duty and attached to the 29th Infantry Brigade at Schofield Barracks, Hawaii. One other infantry unit was federalizedCompany D, 151st Infantry, from Indiana. After training at Fort Benning, Georgia, this long range patrol company served in Vietnam for eleven months. It was the only infantry organization from the reserve components to participate in the war.

• In the second half of 1969 the number of infantry units started to decline for the first time since the Vietnam buildup began. President Richard M. Nixon's decision to withdraw U.S. forces gradually from Southeast Asia was accompanied by a plan to reduce the strength of the Army. Among the first units to be redeployed were six infantry battalions organic to the 9th Infantry Division. They left Vietnam in July and August 1969, and were inactivated in August and September at Fort Riley, Kansas, and Schofield Barracks, Hawaii. By mid-December 1969, all infantry units from the reserve components had been released and reorganized at their home stations. Meanwhile, the second increment of organizations scheduled for redeployment was in the process of leaving Vietnam.

• Although airmobile and light infantry units were most common in Vietnam, other types of infantry were not neglected elsewhere during the late 1960's. Only a handful of mechanized units went to Vietnam, but numerous mechanized infantry battalions were assigned to mechanized and armored divisions in Europe and in the United States. Most airborne personnel in Vietnam lost their jump pay, because their units did not have the opportunity to utilize their unique capabilities, but the airborne battalions in the strategic reserve proved their constant readiness in various emergencies, such as the 1965 Dominican Republic crisis and several domestic civil disturbances. In spite of the heavy infantry commitment in Vietnam, as the decade of the 1960's ended there were still infantry units stationed all over the world-in West Germany, Berlin, Korea, the Canal Zone, Alaska, and Hawaii, as well as in the continental United States. The Regular Army infantry was backed up by Army Reserve and Army National Guard infantry units which, although fewer in number, were better trained and equipped than ever before.

• The infantry organizational structure existing in 1969 was well suited to the strategy and tactics of flexible response, but regardless of the great variety of infantry units, many of them highly specialized, the basic mission of the infantry remained unchanged. The infantryman of the future may be armed with the SPIW, may wear a spacesuit-like uniform with a built-in two-way radio, and may be transported by his own individual jet propulsion system. Nevertheless, his job will continue to be essentially the same as it has been since 14 June 1775, the birthday of the United States infantry and of the United States Army-to close with and destroy the enemy.

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• page created 10 September 2001