- Chapter III:
(2-24 October 1966)
illustrates a number of innovations which were used throughout
Vietnam. These innovations represented important changes in the
tactical, technical, and psychological sides of warfare. The
helicopter played an enormous part, not only in lifting troops into
combat but also as aerial rocket artillery, in the evacuation of
casualties, in logistical support, and in the development of new
lightweight equipment. IRVING also demonstrates the use of civic
action and psychological warfare in counterinsurgency operations. In
addition to being outflanked by vertical envelopment, the enemy was
attacked by strategic bombers and by U.S. infantrymen invading his
underground hiding places.
- During October of 1966,
allied military forces combined efforts in three closely co-ordinated
operations to destroy the enemy in the central and eastern portions of
the Republic of Vietnam's Binh Dinh Province and to uproot the Viet
Cong's political structure along the province's populated coastal
region. In a period of twenty-two days, the 22d ARVN Division, the
Republic of Korea Capital Division, and the U.S. 1st Cavalry Division
(Airmobile) were to dominate the battlefield to such an extent that
the aggressor had only one alternative to fighting: surrender. The
enemy not only suffered heavy personnel losses in decisive combat, but
many of his vital logistic and support bases were discovered and
destroyed. The victory meant that the central coastal portion of Binh
Dinh Province and hundreds of thousands of citizens were returned to
the control of the South Vietnamese government. The people of the
province were freed from Viet Cong terrorism and extortion for the
first time in many years, and the groundwork was laid for a better
life. The U.S. 1st Cavalry Division's contribution in this campaign to
pacify Binh Dinh Province was Operation IRVING.
- IRVING began on 2
October 1966; however, the development of the battlefield started many
days before. The enemy had been driven out of his bases in the Kim Son
and 506 valleys and channeled toward the sea. In Operation THAYER I in
September, strong U.S., South Vietnamese, and Korean attacks from all
sides uprooted elements of the 610th North Vietnamese Army Division
from their mountain
- sanctuaries, uncovering major
medical, arms, supply, and food caches, a regimental hospital, and a
large antipersonnel mine and grenade factory. A series of fierce
battles forced the enemy into a natural pocket bounded by the Phu Cat
Mountains on the south, the coastline on the east, the Nui Mieu
Mountains on the north, and National Route 1 on the west, The battle
lines for Operation IRVING had been drawn.
- The 1st Cavalry Division
planned for Operation IRVING in minute detail. The division staff
concentrated on intelligence, psychological operations, population
control, and civic action projects as well as combat operations. If
combat against the enemy was to be successful, the psychological,
population control, and civic action aspects had to be effective. In
the same pocket with the enemy were some 250,000 civilian residents,
plus important rice farming and salt production areas. To avoid
noncombatant casualties, population control measures were incorporated
into the psychological operations program. Some twelve million
leaflets and 150 radio broadcast hours were used during Operation
IRVING to help control the civilians. Curfews were established, and at
times villagers were requested to stay where they were until more
specific instructions were given. Psychological efforts were also
geared to appeal to the enemy. For example, substantial rewards were
offered for surrendered weapons.
- By D-day for Operation IRVING,
the Free World Military Assistance forces were in position. Elements
of the 1st and 3d Brigades of the 1st Cavalry Division air-assaulted
into objectives well inside the IRVING pocket. Simultaneously, the
ARVN and Korean elements coordinated attacks in the southern portion
of the battle area so that all three schemes of maneuver would
complement one another. The 22d ARVN Division launched a ground attack
to the northeast with two infantry battalions and two airborne
battalions. The Republic of Korea Capital Division attacked northward
through the Phu Cat Mountains. On the South China Sea, the ARVN junk
fleet and the U.S. Navy sealed escape routes to the sea and provided
fire support from the destroyers Hull and Folson and smaller
- The 1st Cavalry Division
attacked at 0700 hours on the morning of 2 October. Colonel Archie R.
Hyle, commander of the 1st Brigade, deployed the 1st Battalion, 8th
Cavalry, to gain objective 5060; the 2d Battalion, 8th Cavalry, to
secure objective 506A; and the 1st Battalion, 12th Cavalry, to attack
objective 506B. The 3d Brigade commander, Colonel Charles D. Daniel,
attacked objective 507 using the 1st and 5th Battalions of the 7th
Cavalry. The 1st Squadron, 9th Cavalry, under the control of Major
General John Norton, the division commander, was assigned its normal
reconnaissance mission over the division's area of interest. Decisive
combat with the enemy was to occur shortly after the operation began.
- Early on the morning of D-day,
elements of the 1st Squadron, 9th Cavalry, were conducting
reconnaissance operations in the vicinity of Hoa Hoi and observed
seven North Vietnamese Army soldiers in the village. Troop A landed
its infantry elements in the village area and supported them with
armed helicopters. They soon were engaged against a large enemy force
that had fortified the village. When advised of the situation at Hoa
Hoi, Colonel Hyle called for the 1st Battalion, 12th Cavalry, already
airborne en route to another objective. Lieutenant Colonel James T.
Root, commander of the 1st Battalion, issued new orders from his
command and control helicopter, and the battalion turned to the
- B Company was the first unit
of the 1st Battalion to arrive at Hoa Hoi. Under the direction of
Captain Frederick F. Mayer, Company B landed 300 meters east of the
village and quickly maneuvered to assault the enemy's fortified
positions. Although wounded, Captain Mayer directed the unit's drive
toward the well-prepared enemy bunker system. While advancing across
an open area, the unit came under extremely heavy fire and was
momentarily pinned down. Members of the 2d Platoon, Company B, stood
up and advanced through the enemy fire. One squad, spearheaded by
Private, First Class, Roy Salagar, breached the heavily booby-trapped
perimeter trench, and within minutes the enemy force started
withdrawing into the village.
- At this time A Company
air-assaulted into an area southwest of Hoa Hoi. As the 3d Platoon
came in contact with the enemy, they also encountered civilian
noncombatants in the battle area. First Lieutenant Donald E. Grigg was
deploying his platoon to return fire when several old men, women, and
children walked between him and the enemy. He raced 150 meters through
concentrated fire, picked up two of the small children, and carried
them back to his own lines. The other civilians followed him to
safety. Lieutenant Grigg's platoon then closed in on the enemy and
forced him to withdraw into the village.
- While other elements of the
1st Battalion, 12th Cavalry, were being air-assaulted into the battle
area, the battalion held its fire on the village. A psychological
operations helicopter circled the village with loudspeakers, directing
the civilians to move out of the village and into four specific areas
outside the perimeter. North Vietnamese Army soldiers were asked to
lay down their weapons. During the moratorium, many civilians and
soldiers did as they were directed. After one hour, when it was
evident that no one else was coming out of the village, the 1st
Battalion, 12th Cavalry, began moving in.
- Fierce fighting lasted
throughout the day as elements of the U.S. battalion assaulted the
fortified village. That evening, General Norton reinforced the 1st
Battalion, 12th Cavalry, with Companies A and C of the 1st Battalion,
5th Cavalry. Under the control of Colonel Root, the companies made a
night air assault on the beaches east of
- Hoa Hoi and moved into the
encirclement to help contain the enemy during the hours of darkness.
North Vietnamese soldiers tried in vain to shoot their way out.
Effective artillery support contributed to the containment effort.
Earlier in the day, A Battery, 2d Battalion, 19th Artillery, had been
positioned by assault support helicopters to back up the 1st
Battalion, 12th Cavalry. During the night 883 105-mm. rounds were
fired in the effort to contain the enemy. The battlefield was
illuminated by a U.S. Air Force AC-47 flareship, by artillery, and by
naval guns from the destroyer Ullman. Throughout the night,
helicopters provided fire support, brought in supplies, and evacuated
- At dawn, Company C, 1st
Battalion, 12th Cavalry, attacked south through the enemy position,
while Companies A and B blocked the other side of the village. The
enemy defended with great skill; but the strength of the attack, plus
the well-co-ordinated combat support, brought the battle of Hoa Hoi to
a close. During this 24-hour battle, the 1st Battalion, 12th Cavalry,
and supporting units had killed or wounded 233 enemy soldiers, while
suffering 3 killed and 29 wounded. In addition, 35 North Vietnamese
soldiers were captured, and 15 suspected NVA regulars were detained.
- On D-day of the operation a
B-52 strike was made on a portion of the Nui Mieu Mountains near
objective 506A. The 1st Squadron, 9th Cavalry, conducted a follow-up
damage assessment and discovered documents and seven enemy dead, which
confirmed the presence of elements of the 2d Viet Cong Regiment. All
forces advanced on schedule to reduce the size of the IRVING pocket.
The sweep to the sea continued, using helicopter assaults and land
movement to destroy the enemy forces. On 4 October a co-ordinated
ground attack was made by the 3d Brigade using the 1st and 5th
Battalions, 7th Cavalry. The attack was preceded by extensive
artillery preparation. Thirty enemy soldiers were killed in the
operation. As the sweep operations neared Nuoc Ngot Bay, leaflets and
loudspeakers were used to warn civilians that all boats moving on the
bay would be sunk. Riot control agents were also used during the
operation. The battalions of the 3d Brigade used assault boats brought
in by helicopter to sweep the waterways.
- On 5 October the 1st
Battalion, 12th Cavalry, air-assaulted back to the west into the Soui
Ca Valley to exploit a B-52 strike and to surprise enemy units that
had escaped the IRVING pocket or had secretly moved into the valley
strongholds. In the IRVING battle area, the 1st Cavalry Division
continued to search for North Vietnamese units and to uproot the Viet
Cong. The 1st Squadron, 9th Cavalry, sighted many small groups of
enemy soldiers trying to avoid contact. The cavalrymen fired at them
from armed helicopters and often landed infantry elements to engage
the enemy. On 9 October, while supporting
CH-54 "FLYING CRANE" DELIVERING BULLDOZER TO FORWARD
a sweep along the Hung Loc
peninsula, the 2d Battalion, 20th Artillery (Aerial Rocket Artillery),
fired SS11 missiles at bunkers on the peninsula. The missiles
destroyed the bunkers, thus enabling fifty-five Viet Cong to be
captured without a fight.
- In mid-October, enemy contacts
in the coastal region diminished, and the emphasis of the battle
shifted back to the valleys in the west. Capitalizing on the
information that elements of the 2d Viet Cong Regiment were regrouping
in the Kim Son and Soui Ca valleys, the division quickly airlifted
several battalions into the area. On 13 October, the 1st Battalion,
5th Cavalry, located the main Viet Cong province headquarters,
including official stamps, radios, documents, and typewriters. On 14
and 15 October, in support of the 1st Battalion, Company A of the 8th
Engineer Battalion brought in airmobile engineer construction
equipment. A CH-54 "flying crane" lifted a grader and a
pneumatic roller into the valley. Teams of engineer soldiers called
tunnel rats located, explored, and later destroyed extensive tunnel
complexes constructed by the enemy. Sweep operations in the valleys
turned up additional caches of equipment and supplies.
- During the latter part of
Operation IRVING an artillery raid was conducted by A Battery, 2d
Battalion, 19th Artillery. Four howitzers
- with crews, 280 rounds of
ammunition, and a skeleton fire direction center were airlifted into
areas that the enemy had thought were secure to fire on previously
selected targets that were beyond the range of other tube artillery. The
280 rounds were fired in less than seventeen minutes, after which the
artillery was airlifted back to its base.
- By midnight of 24 October the
battle was over. The enemy had been unable to cope with the airmobility
and versatility of the 1st Cavalry Division (Airmobile). Massive
firepower had decimated the enemy's forces, and his long-secure supply
bases had been destroyed. While suffering 19 men killed itself, the 1st
Cavalry Division had killed 681 enemy soldiers and captured 741. The
rapid reaction of U.S. forces allowed the division for the first time to
capture more enemy soldiers than it killed. The success of Operation
IRVING had a lasting effect on the pacification of Binh Dinh Province.
- The major tactical innovation
illustrated in Operation IRVING Was airmobile combat. An airmobile
operation is one in which combat forces and their equipment move about
the battlefield in aircraft to engage in ground combat. In such an
operation, helicopters not only transport the forces to the battle area,
but also enable them to develop the situation and to reinforce,
withdraw, and displace combat power during the battle. The purpose of an
airmobile assault is to position fresh combat troops on or near-their
tactical objectives. The tactical unit can fly over obstacles and
impassable terrain to land at the strategic point in the battle area.
- The successful airmobile
assaults in Operation IRVING and those conducted by other units in
Vietnam were the result of detailed planning by the participating ground
units, the aviation support elements, and the combat support and combat
service support units. The overall commander of ,an airmobile task force
is the commander of the ground unit making the assault. The aviation
commander directs the helicopter support units and advises the task
force commander on all aviation matters.
- Airmobile operations in Vietnam
were planned in an inverse sequence, similar to airborne operations.
First, the ground tactical plan was prepared. It was the basic airmobile
operation plan. In this plan the commander of the assault unit presented
his scheme of maneuver and plan for fire support in the objective area.
Assault objectives were chosen that insured the accomplishment of the
mission. Landing zones were then carefully selected to support the
ground tactical plan. A fire support plan was developed concurrently in
order to be closely co-ordinated and integrated with the scheme of
- The next step in the sequence
was the development of a landing plan. It insured the arrival of the
various elements of combat power at
- the times and locations
required. The landing plan included the sequence, time, and place for
landing troops, equipment, and supplies.
- An air movement plan was then
prepared, which was based on the previous plans. Its purpose was to
schedule the movement of troops, equipment, and supplies by air from
pickup to landing. Details such as flight speeds, altitudes, formations,
and routes were specified.
- Finally, a loading plan was
developed. It insured the timely arrival of units at pickup zones and
the loading of troops, equipment, and supplies on the correct aircraft
at the proper time.
- Often, because of rapidly
changing tactical situations, the airmobile planning sequence was
abbreviated. All elements of the planning were considered, but in a
shorter form. The actions of Colonel Root of the 1st Battalion, 12th
Cavalry, in Operation IRVING provide an excellent example. Plans were
prepared for an airmobile assault by the 1st Battalion on objective
506B. However, when directed at the last minute to assault the village
of Hoa Hoi, Colonel Root prepared and assigned new orders while en route
by air to the new objective. Sound training and complete standing
operating procedures for the ground and aviation units contributed to
the quick development of airmobile plans and orders.
- Radio communications and
prearranged visual signals, colored smoke, and flares were the primary
means of communication during airmobile assaults.
- Fire support was extremely
important during these operations and included artillery, naval gunfire,
armed helicopters, tactical aircraft, strategic bombers, and mortars.
During a specific operation the task force may have been supported by
any or all of these means. All available fire support was controlled by
the airmobile task force command group from its command and control
helicopter. Preparatory fire on and around the landing zone was usually
brief but intense and continuous, with no pause in the firing from the
various sources. Fire was shifted from the landing zone only seconds
before the first flight of helicopters touched down. The firing was
diverted to selected locations to protect the assault force, and then
redirected to support the expansion of the objective area. Smoke was
often used by artillery or by a specifically equipped helicopter to mask
the movement of the assault force.
- Division commanders in Vietnam
concluded that airmobile assaults greatly increased the speed and
flexibility of their operations, extended their area of influence, and
provided them with the means to concentrate forces quickly and to move
them after accomplishing the mission.
- In World War II and in the
Korean War, where combat ranges were normally greater than in Vietnam,
gunnery errors seldom resulted in friendly casualties. Any round that
cleared friendly lines was
- usually safe. In Vietnam,
however, about 50 percent of all artillery missions were fired very
close to friendly positions or into an area virtually surrounded by
converging friendly forces. An error could harm U.S. or allied troops or
civilians living in the areas of operations. The senior officer in
charge of each area of operation was specifically charged with the
safety of his troops and of the local population. His fire support co-ordinator
worked out the details required to insure this safety. He used such
devices as no-fire lines, fire and fire support co-ordination lines, and
clearances with the lowest level of the Republic of Vietnam government
(usually the district) that had U.S. advisers. Fire support co-ordinators
maintained a map marked to show specified-strike zones and no-fire
zones, all based on the rules of engagement drawn up jointly by U.S. and
Vietnamese high commands. They were applicable to all allied forces and
were meant to protect the lives and property of friendly forces and
civilians and to avoid the violation of operational and international
boundaries. The rules were specific. They covered each general type of
operation, such as cordon and search, reconnaissance in force, a
waterway denial operation, and defense of a base camp. They also
governed the establishment of zones. No-fire zones were those in which
persons loyal to the Republic of Vietnam government lived. The rules
provided for the different curfew hours which each province chief
specified for all Vietnamese civilians in urban centers, along main
supply routes, in New Life hamlets, and in the woods and fields.
Presumably, all persons who were not in a no-fire zone obeying curfew
restrictions were suspect.
- Naturally, the rules did not
limit the right of a unit to defend itself, and a unit attacked could
take necessary aggressive action against the enemy with any means
available. As Major General Harris W. Hollis later stated:
- The clearest test of the
hostility of a target was the receipt of fire from it-prima facie
evidence, as it were. In such cases our units or aircraft could return
fire as a matter of self-preservation, but only to the degree necessary
to deal with the threat. No overkill airstrike could be called down on a
Viet Cong sniper without proper prior clearance. I am convinced that
this restraint by each responsible commander played a key role in
minimizing civilian casualties.
- The most serious problem created
by clearance requirements was the loss of indirect fire responsiveness
and surprise. As a rule, clearances added approximately three minutes'
delay for each agency required to take action on the request. Agencies
within a unit caused the least delay and complications.
- To reduce the time lost in
firing missions, nonpopulated areas were frequently cleared in advance
of operations and for night intelligence and interdiction fire.
Commanders were expected to establish appropriate liaison with local
government agencies and with Free
- World forces to provide quick
request channels and to mark specified-strike zones whenever possible.
- With the tremendous increase in
the use of aircraft in the Republic of Vietnam came the need to assign
responsibilities for their safety from indirect ground fire. Operational
responsibility for the air advisory agencies was usually given to the
major field artillery headquarters in the area. The agencies were
generally located with a battalion operations section. Aircraft entering
the area of an air advisory agency usually radioed in for clearance.
They were given the locations of all fire or of safe routes to travel.
The agency notified aircraft in its area about new artillery missions by
calls over its network. The responsibility for all fire above 5,000 feet
was passed by the air advisory agencies to the U.S. Air Force.
- An important innovation in
the Vietnam War was the integration of strategic air power into the
ground combat plan. Similar use of heavy bombers in Korea was on a much
more limited scale. The Strategic Air Command, with its B-52 bombers
flying at extremely high altitudes, out of sight and out of hearing of
the unsuspecting enemy, delivered devastating blows against fortified
positions. Two B-52 strikes were used in Operation IRVING.
- Ground commanders used the
B-52's against targets of high tactical value. Enemy troop
concentrations in base areas were common targets. When a B-52 target was
identified, a request was passed through command channels to a joint
Army-Air Force targeting committee. If the request was approved, the
target was included in the bombing schedule and the requesting unit was
notified. The tactical commander could then complete his plans for using
the B-52 strike to its best advantage on the ground. The follow-up
operation after the bombing raid, depending on the nature of the target,
ranged from a small patrol reconnoitering the area to a large-scale
sweep operation involving a battalion-size unit or larger. Artillery was
often used following a B-52 strike to hit enemy personnel moving back
into the target area.
- The tactical mobility furnished
by the helicopter and the communications available to the ground
commander were effectively used to capitalize on B-52 strikes. While the
dust and smoke from the bombs were still in the air, the heliborne
assault could begin, taking maximum advantage of the shock and confusion
among the enemy troops.
- One of the major artillery
innovations of the Vietnam War was aerial rocket artillery, commonly
called ARA, and later, aerial field artillery. The fire support
potential of the helicopter had been appreciated for some time.
Gunships, in the form of UH-1 helicopters armed with various
combinations of machine guns, rockets, and grenade launchers, had been
effectively used throughout the conflict.
- Theoretically, however, the
gunships provided light fire support rather than the artillery type.
Aerial rocket artillery, on the other hand, was organized and employed
as artillery. In the words of Lieutenant Colonel Nelson A. Mahone, Jr.,
commander of the 1st Cavalry Division's 2d Battalion, 20th Artillery (ARA),
"We consider ourselves a breed apart, and our success tends to
support this." Aerial rocket artillery fire was requested through
artillery channels and was usually controlled by an artillery forward
observer. ARA was particularly effective in support of airmobile forces
beyond the range of the division's ground artillery. Moreover, ARA
fulfilled the need for a highly responsive and discriminating means of
fire support for the infantry during its most vulnerable phase of an air
assault, namely, just after its arrival on the landing zone. Aerial
rocket artillery helicopters circling overhead watched over the landing
zone and movement of the troops. If necessary, they immediately
responded to fire requests by firing directly on the target.
- Although ARA was frequently used
beyond the range of cannon artillery, it also augmented this fire. ARA
was assigned the normal tactical missions of conventional artillery.
Normally, however, it was used in general support with control retained
by division artillery because of ARA's range and flexibility.
- The main armament of the ARA
consisted of the M3 2.75-inch folding-fin rocket system mounted on UH-1
helicopters, and later on the Cobra version. In addition, the ARA was
capable of using the SS 11 antitank wire guided missiles. SS 11 fire was
extremely valuable against point targets, such as bunkers located on
hillsides and other enemy fortifications. Medium and heavy artillery in
Vietnam was normally located in semipermanent base camps or fire bases
to provide support within the tactical area of operations. Continuous
fire, or the threat of it, from these weapons caused the enemy to move
his base camps and supply caches out of range. The artillery raid was
used against these outlying enemy installations by moving to a position
in range of the target, firing on the enemy, and then returning to the
artillery's base. Medium and heavy self-propelled weapons were
particularly well suited for raids, although light and medium artillery
lifted by helicopters could be used. In fact, the airmobile divisions
achieved excellent results with helicopter-borne 105-mm. howitzers used
in this fashion, and they developed expedient methods of clearing jungle
artillery bases. This technique was used effectively in Operation
- In October 1969, the 101st
Airborne Division (Airmobile) developed the radar raid in order to
extend the influence of its artillery. This type of raid was conducted
by frequently moving AN/PPS-4 or AN/PPS-5 radars with security forces to
dominant terrain features outside fire bases. These forces could then
provide surveillance along
- routes of infiltration
previously masked by terrain. By conducting raids within existing
artillery ranges, discovered targets could be rapidly engaged.
- During Operation IRVING, Company
C, 2d Battalion, 8th Cavalry, discovered a tunnel complex in the Nui
Mieu Mountains. The complex included five vertical shafts, thirty to
fifty feet deep, with horizontal tunnels connecting them. After
searching the tunnels, a squad of engineers from the 8th Engineer
Battalion destroyed the complex with demolitions.
- A significant feature of the war
in Vietnam was the widespread use of tunnels and other underground
facilities by the enemy. Tunnels were a major factor in the enemy's
ability to survive bombing attacks, to appear and disappear at will, and
to operate an efficient logistic system under primitive conditions. By
the end of 1970, 4,800 tunnels had been discovered. Most of the
discoveries were made during sweep operations by Free World military
forces. Tunnel complexes were also located through local informers and
by means of dogs trained to find underground facilities. An electronic
tunnel detector and a seismic detector were tested with limited success.
Several techniques have been developed to force the enemy to evacuate
tunnels. Tunnel rat teams were formed by many infantry and engineer
units to clear and explore tunnels. An exploration kit consisting of
headlamps, communications equipment, and a pistol assisted the team. A
Tunnel Explorer Locator System was developed to map the tunnel and to
monitor the progress of the tunnel rat as he moved through the tunnel.
Proven chemical techniques were the use of smoke to locate tunnel
openings and a riot control type of tear gas, known as CS, to drive
enemy personnel from underground.
- After tunnels were cleared and
searched, they were destroyed to prevent their further use by the enemy.
Methods developed to keep the tunnels from being used again included
placing riot control agents in the tunnel, sealing the entrance with
explosives, using demolitions to destroy the tunnels, pumping acetyline
into the tunnel and igniting the gas by explosives, and using
construction equipment to crush the tunnels.
- The first use of riot control
agents in Vietnam was on 23 December 1964 when CS grenades were
air-dropped as part of an attempt to rescue U.S. prisoners being held at
a location in An Xuyen Province. In this operation no contact was
actually made with the enemy. In February 1965, General Westmoreland
informed the senior advisers of the four corps tactical zones that U.S.
policy permitted the use of riot control munitions in self-defense. Kits
containing protective masks and CS grenades were issued to each
subsector advisory team for self-defense. These kits were not intended
for offensive use by U.S. troops.
MEMBERS OP AN ENGINEER TUNNEL RAT TEAM explore
Viet Cong tunnel.
- In March 1965, New York Times
correspondent Peter Arnett described the use of riot control agents by
ARVN forces. His report generated much controversy in both the
American and foreign press and led to an examination, by both U.S.
military and political agencies, of the pros and cons of the use of CS
in Vietnam. An independent action by the commander of the 2d
Battalion, 7th Marine Regiment, on 5 September 1965 significantly
influenced subsequent policy on the use of CS in Vietnam. The 2d
Battalion encountered an enemy force entrenched in a series of
tunnels, bunkers, and "spider" holes. Since there was
information that women and children were also present, CS was used to
help clear the complex. As a result, 400 persons were removed without
serious injury to noncombatants. However, on 7 September 1965, all
senior U.S. commanders were reminded that "MACV policy clearly
prohibits the operational use of riot control agents."
- Later the same month, the
Military Assistance Command, Vietnam (MACV), decided that the military
usefulness of CS warranted a request to higher authority for
permission to use it in the upcoming Iron Triangle operation. The
request was forwarded to Secretary of Defense Robert S. McNamara, who
granted permission for CS to be used in the Iron Triangle operation
only. In the following weeks, a much-liberalized policy on the use of
CS was developed, and on 3 November 1965 the joint Chiefs of Staff
notified General Westmoreland that he was authorized to use CS and CN
(another tear gas) at his discretion to support military operations in
South Vietnam. This authority was further delegated to the major
- MACV Directive 525-11, dated
24 July 1967, concerned the use of riot control agents in tactical
operations. Using these agents in situations where noncombatants were
involved was deemed particularly appropriate. The U.S. senior advisers
to the four ARVN corps were empowered to authorize the use of CS by
U.S. forces in support of the South Vietnamese Army. U.S. advisers at
all levels were to encourage their counterparts in the Vietnamese
armed forces to use CS and CN whenever such use offered an over-all
tactical advantage. The use of riot control agents in situations
involving civil demonstrations, riots, and similar disturbances was
specifically prohibited without prior approval by the commander of the
Military Assistance Command, Vietnam. Riot control agents were treated
as normal components of the combat power available to the commander.
- The early use of CS was
limited by the shortage of standard munitions. The only munitions
available at first in operational quantities were the M7 and M25
grenades. Many other ground and air munitions were being developed and
later were tested and used in Vietnam.
- One of the first uses for M7
CS grenades was to flush caves, tunnels, and other underground
fortifications. The 1st Cavalry Division
RIOT HAND GRENADE, CS1,
- (Airmobile) effectively used
CS grenades during Operation MASHER-WHITE WING, which took place in a
highly populated area. CS grenades when used on suspected enemy areas
enabled 1st Cavalry troops to determine whether the occupants were
civilians in hiding or armed Viet Cong. On another occasion,
forty-three Viet Cong were pursued into a cave. All forty-three were
driven out again, however, when CS hand grenades were thrown into the
cave. The only casualty occurred when one Viet Cong refused to
- The burning-type CS grenade,
along with HC smoke grenades, was also used in conjunction with the
M106 Riot Control Agent Dispenser, dubbed Mity Mite, a portable
blower. This system was capable of forcing the Viet Cong and North
Vietnamese Army out of unsophisticated tunnel complexes, as well as
helping to locate hidden entrances and air vents. The Mity Mite system
could not drive personnel from the more complex, multilevel tunnel
systems, many of which contained airlocks. However, bulk CS was widely
used in tunnel denial operations, in which bags of CS were exploded
throughout the tunnels. The 1st Infantry Division's experience
indicated that the tear gas remained effective for five to six months
if the tunnel was sealed. The efficiency of powdered CS in restricting
the enemy's use of fortifications and the difficulty of destroying the
numerous bunkers and other fortified structures by conventional
explosives led to the development of many techniques for dispensing CS
in these enemy defenses.
- The 1st Cavalry Division
(Airmobile) termed their expedient munition the Bunker Use Restriction
Bomb (BURB). The BURB consisted of a cardboard container for a
2.75-inch rocket warhead, two nonelectric blasting caps, approximately
twenty-five seconds of time fuze, and a fuze igniter. The device was
filled with CS and taped shut. The blasting caps provided sufficient
explosive force to rupture the container and to spread the CS49. Other
units developed their own expedient CS munitions for contaminating
- The acceptance of CS as a
valuable aid in combat operations led to the development of several
weapons systems. These included the E8 riot control launcher; the XM15
and XM165 air-delivered tactical
- CS clusters; the 40-mm. CS
cartridge for the M79 grenade launcher; the 4.2-inch mortar CS round;
the BLU52 chemical bomb (Air Force); and the XM27 grenade dispenser.
The E8 chemical dispenser was used effectively by the 2d Battalion,
5th Marine Regiment, during Operation HUE CITY between 3 and 15
February 1968. The action during this period was characterized by
close, intense house-to-house combat. Engagements with the enemy were
usually at distances from 20 to 150 meters, with maximum distances of
300 meters. The use of air and artillery forces was limited by weather
conditions and by the closeness of the enemy to friendly troops. The
tactical situation required almost continual assaults on fortified
buildings and some bunkers. The use of the E8 CS dispenser was
credited with neutralizing the enemy's firepower during the assaults.
- The greatest amount of CS
employed in Vietnam was bulk CS1 or CS2 dispensed to restrict the
enemy's use of terrain. Contamination of large areas or of terrain not
accessible to friendly ground forces was normally carried out by
air-delivered 55-gallon drums that contained eighty pounds of CS. The
drums were dropped from CH-47 helicopters using locally fabricated
racks, which allowed the unloading of thirty drums on the target. The
major targets for these drops were known or suspected base camps, rest
areas, and infiltration routes.
- Air-delivered, burning-type
munitions also produced good results as evidenced by the use of thirty
E158 air-delivered CS clusters in support of South Vietnamese Rangers
on 3 February 1968. The Rangers were heavily engaged by a large Viet
Cong force deployed in a factory complex in the Cholon area of Saigon.
After several attacks by the Rangers had been repulsed, the CS
munitions were dropped into the area by helicopter. The Ranger assault
which followed the CS drop was successful.
- The use of riot control agents
by U.S. and allied forces in Vietnam cannot be likened to the gas
warfare of previous wars. Whereas mustard and chlorine gas often
resulted in permanent injury and death, CS and CN produced only
temporary irritating or disabling physiological effects. Their use
saved the lives of many allied soldiers, civilians, and enemy
- Because of the extensive use
of helicopters in the Republic of Vietnam, landing zones had to be
rapidly constructed in heavily forested areas, like those surrounding
the Kim Son and Soui Ca valleys. The engineers in Vietnam were thus
challenged to reduce the landing zone construction time, in order to
meet the needs of the quickly shifting tactical situation. Landing
zone requirements ranged from the hasty construction of a helicopter
pad, from which to provide emergency resupply or medical evacuation,
to the development of large landing zones, able to handle sufficient
aircraft to support battalion or brigade operations.
- Experience gained by engineer
units in Vietnam led to the development of landing zone construction
kits that contained the necessary tools and demolitions to prepare a
landing zone for one aircraft. If the engineer team could be landed
near the new construction site, they would rappel from the helicopter
or climb down rope ladders. When sufficient area had been cleared,
air-portable construction equipment or additional tools and
demolitions were lifted in to expand the new landing zone.
- The "combat trap"
was developed after experimentation. In a joint Army and Air Force
effort, an M121 10,000-pound bomb was parachuted from a fixed-wing
aircraft or helicopter over the desired landing zone site and
detonated at a height that would clear away the dense foliage but not
create a crater in the earth. After the combat trap had finished its
job, a construction party and equipment were taken by helicopter to
the new landing zone to expand it to the desired size.
- The key to the success of
airmobile operations often was the ability of the engineer battalion
to construct landing sites for helicopters and fixed-wing aircraft
quickly. To support the airmobile division adequately, air-portable
construction equipment was developed for the division's engineer
battalion. Engineer equipment that could be moved into the forward
areas by helicopter included roadgraders, bulldozers, scoop loaders,
scrapers, and cranes, each of which was sectioned and lifted into the
objective area in two loads,, and then assembled for operation.
Backhoes, small bulldozers, dump trucks, and compaction equipment
could be transported in one helicopter lift.
- Throughout Operation IRVING
the 8th Engineer Battalion used airmobile construction equipment to
clear and expand landing zones and artillery positions and to
construct defensive positions. On 14 October, a bulldozer, a grader,
and a roller were sectioned and airlifted to the command post of the
1st Brigade, 1st Cavalry Division, to expand the existing landing zone
and to construct an aircraft refueling area.
- The cry of "Medic!
Medic!" has been heard in all wars involving the United States,
and the company aidman is still the first link in the chain of medical
support. In Vietnam the aidman had a new lifesaving tool, the medical
evacuation helicopter, better known as Dust-off. Because of the
bravery and devotion to duty of these helicopter pilots and crews,
many lives were saved. Often Dust-off choppers landed under heavy
enemy fire to pick up wounded soldiers or hovered dangerously above
the battlefield as an injured man was hoisted up to the helicopter.
The seriously wounded were taken directly from the field to a
hospital, often bypassing the battalion aid station and the clearing
station. This rapid means of evacuation saved many lives and greatly
improved the soldiers' morale. Each soldier
DUST-OFF HELICOPTER HOISTS WOUNDED MAN FROM BATTLEFIELD
- knew that if he were wounded
he would be picked up immediately by Dust-off.
- Although the helicopter was a
great help to the men in Vietnam, it required considerably more
engineer support than the Army originally expected. As the commanding
general of the engineers in Vietnam, Major General David S. Parker,
noted in his debriefing report, "In addition to advanced landing
zones, built primarily by division engineers through a number of
ingenious techniques, there have been extensive requirements for
revetments, parking areas, maintenance hangars, and paved working
areas for POL, ammunition, and resupply operations. The construction
has increased effectiveness through added protection and improved
- Parked aircraft were prime
targets for the enemy and, as such, were subjected to many damaging
small arms, mortar, and .rocket attacks. Therefore, the protection of
organic aircraft was a major concern to all commanders. Engineers were
charged with providing lightweight, portable, and easily erected
revetments for all helicopters without decreasing the helicopter's
reaction time. Construction materials included airfield landing mats,
plywood, corrugated steel, and soil.
- The T17 nylon membrane was an
important development for engineer support of airmobile operations.
The membrane was designed as a moisture barrier and dust cover for
landing zones and strips. It was also used successfully as the surface
for unloading aprons and parking areas, thereby greatly reducing
construction time. It was not a cure-all, however, since it added no
bearing strength to the soil. The blast from helicopters often created
large dust clouds, which increased aircraft collisions and maintenance
difficulties. The T17 membrane was one way of reducing dust, but
peneprime, a commercial composition of low-penetration grade asphalt
and a solvent blend of kerosene and naphtha, was the best dust control
agent tried in Vietnam. During Operation IRVING, the 8th Engineer
Battalion used some 38, 600 gallons of peneprime on helicopter pads,
refueling areas, and airfield turnarounds.
- Operation IRVING was an excellent
example of recent changes in the tactics of war. The airmobile division, with
Vietnamese and Korean assistance, demonstrated its flexibility and power as
it pursued and destroyed a large enemy force in a populated countryside. The
helicopter became an integral part in maneuver plans, division artillery,
medical evacuation, and the transport of heavy equipment. The enemy was hit
with everything from strategic bombers to tunnel rats, within the confines
of special rules of engagement. Psychological operations and population control
were also included in the tactical plan.
- page created 15 December 2001
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