Breaker of Armies c34philhaun.scripts.mit.edu/Researchwebpage/wp-content/... · 2015. 8. 6. · The Vietnam Air Power Debate Four decades after the Vietnam War, debate still surrounds

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Breaker of Armies: Air Power in the Easter Offensive and the Myth of Linebacker I and II

Phil Haun and Colin Jackson

Abstract: Most traditional accounts identify the Linebacker I and Linebacker II campaigns as the most effective and consequential uses of U.S. air power in the Vietnam War. They argue that deep interdiction in North Vietnam played a central role in the defeat of the Easter Offensive and that subsequent strategic attacks on Hanoi forced the North Vietnamese to accept the Paris Accords. We find that these conclusions are false. The Linebacker campaigns were rather ineffective in either stopping the Communist offensive or compelling concessions. The most effective and consequential use of U.S. air power came in the form of close air support and battlefield air interdiction directly attacking the North Vietnamese Army in South Vietnam. The success of these air strikes hinged on the presence of a U.S.-operated, tactical air control system that incorporated small numbers of ground advisors, air liaison officers, and forward air controllers. This system, combined with abundant U.S. aircraft and a reasonably effective allied army, was the key to breaking the Easter Offensive and compelling Hanoi to agree to the Paris Accords. The effectiveness of CAS and BAI and the failure of interdiction and strategic attack in the Vietnam War have important implications for the use of air power and advisors in contemporary conflicts in Iraq, Syria, and Afghanistan.

Most accounts of U.S. air power in the latter phases of the Vietnam War revolve

around the Linebacker I and II campaigns of 1972.1 While scholars offer a range of

explanations for the success of these campaigns, the U.S. Air Force has long seen them as

proof of the politically decisive effects of interdiction and strategic attack. The widely

held belief that these independent air operations on North Vietnam coerced Hanoi to sign

the Paris Peace Accords is wrong.2 It was, rather, the defeat of the North Vietnamese

Army (NVA) during the Easter [Nguyen-Hue] Offensive in South Vietnam that convinced

the North to accept a peace agreement in October of 1972. U.S. air power was decisive,

1 Robert Pape, Bombing to Win (Ithaca NY: Cornell University Press, 1996); Mark Clodfelter, The Limits of Air Power: The American Bombing of North Vietnam (Lincoln, Nebraska: University of Nebraska Press, 1989); Stephen Randolph, Powerful and Brutal Weapons (Cambridge MA: Harvard University Press, 2007); Marshall Michel, The Eleven Days of Christmas (San Francisco: Encounter Books, 2002). 2 Henry Kissinger, The White House Years (New York: Simon and Schuster, 1979), 1303; John Vogt, “Speech Delivered to Air Force Association, Honolulu, HI, 15 November, 1973,” AFHRA K168.06-234 73/11/15-73/12/04, 17; Clodfelter, 167-8; Robert Pape, “Coercive Air Power in the Vietnam War,” International Security 15:2 (Fall, 1990), 105.


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not with deep interdiction or strategic air strikes, but by stopping the NVA’s blitzkrieg in

the South and breaking its army in the process.

U.S. air power proved most effective in the role of close air support (CAS) and

battlefield air interdiction (BAI), using tactical fighter-bomber aircraft (tacair), ground

radar controlled B-52 Arc Light strikes, and fixed- and rotary-wing gunships to attack

NVA conventional formations. While the aircraft platforms and weapons were important,

it was the system of U.S. targeting and fire control that was the critical factor in the

U.S./South Vietnamese victory in the South. A small cadre of Army ground advisors and

Air Force liaison officers used the tactical air control system (TACS) to provide the

targeting information, coordination, and final strike control for successful air operations.

Where the TACS was present, U.S. air power and South Vietnamese troops formed an

effective combined arms team, blunting the NVA attacks near Saigon and in the Central

Highlands. By contrast, in Quang Tri province, where the U.S. TACS was transferred to

Vietnamese control, the lack of effective coordination resulted in the collapse of the South

Vietnamese Army of the Republic of Vietnam (ARVN) along the demilitarized zone

(DMZ). The subsequent reintroduction of an American TACS, the replacement of the

South Vietnamese commander, and hard fighting on the part of the ARVN culminated in

the recapture of Quang Tri City and the final collapse of the Communists’ Easter

Offensive. In the fall of 1972, with its army crippled and its forces falling back on all

fronts, Hanoi opted to pursue a peace deal with the United States.

In addition to CAS and BAI, in the second month of the Easter Offensive, the U.S.

launched the heralded Linebacker I air interdiction campaign to disable North Vietnamese

railroad lines and halt the flow of supplies to the south. By that time, however, the NVA


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had already deployed its heavily armored divisions and had stockpiled sufficient supplies

and ammunition to wage a multi-month blitzkrieg in the south. As a result, Linebacker I

did not play a significant role in the defeat of the NVA in the Easter Offensive, nor did it

play a major, independent role in compelling the North Vietnamese to seek a diplomatic

agreement.

The persistence of the Linebacker myth and the neglect of the role of CAS and

BAI in the Easter Offensive have their roots in service politics. For the U.S. Air Force,

Linebacker I and II were the exorcism of the political constraints of Rolling Thunder and a

validation of precision attack on strategic targets. The Air Force had little institutional

interest in telling the story of how independent air operations in North Vietnam failed in

Linebacker I or how Linebacker II succeeded only in bringing the North Vietnamese back

to Paris to sign an agreement to which they had previously agreed. They had even less

incentive to acknowledge the decisive impact of CAS and BAI missions in the South as

they represented a subordination of air assets to ground commanders. Similarly, the Army

had little to gain by highlighting how the largest battle of the Vietnam War was won, not

by U.S. combat troops, but by a weak ally supported by a handful of military advisors and

air liaison officers who coordinated the firepower of the Air Force and Navy to tip the

scales against the more powerful opponent.

This reexamination of the air offensives of 1972 has a direct bearing on the

contemporary debates over U.S. air power and its integration with ground forces. First, it

shifts the debate from the general efficacy of air power to an evaluation of rival uses of air

power. The experience of the Easter Offensive suggests that direct attack on conventional

armies is more effective than interdiction and strategic attack. By contrast, the history of


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the 1972 air campaigns undercuts claims that Linebacker I and II are examples of decisive

air campaigns independent of friendly ground forces. Second, this case highlights the

primacy of the air control system and missions over the aircraft and weapons involved.

Having a system to integrate U.S. air power into a friendly ground force’s scheme of

operations is as important as the specialized platforms, sensors and precision weapons

employed to seek out and destroy enemy armies. Third, the key ingredient in the air

control system is the small cadre of trained ground advisors, air liaison officers, observers,

and controllers. The history of the Easter Offensive suggests that a sufficient number of

skilled personnel, supported by a moderately capable client army, can stop and even roll

back large-scale conventional invasions. While much has changed in weapons technology

since 1972, the primacy of the air control system and the importance of small numbers of

skilled air and ground controllers have not. The experience of 1972 strongly suggests that

the presence of ground advisors and air liaison officers in a U.S.-run TACS can make the

difference in the effective use of U.S. air power alongside allied ground forces. These

findings have direct bearing on the contemporary debates over the significance, scale and

efficacy of U.S. air power employment and advisory support across a range of theaters

including Afghanistan, Libya, Yemen, Syria, Iraq, and Ukraine.

The Vietnam Air Power Debate

Four decades after the Vietnam War, debate still surrounds the role air power

played in convincing Hanoi to sign a peace agreement in January of 1973. Three schools

of thought have emerged over why air power proved effective in 1972, when it had failed

up until that point. U.S. Air Force and Navy officers who commanded the air operations

in Vietnam during the Rolling Thunder campaign of 1965 to 1968 claim that the political


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constraints imposed by President Johnson were responsible for the failure of the

campaign.3 In 1972, by contrast, détente allowed Nixon to bomb Hanoi without the fear

of escalation.

Air power historian Mark Clodfelter argues that the decisive factor was the

decrease in U.S. political objectives following the Tet Offensive of 1968.4 In 1965, the

United States demanded Hanoi curtail its support of the Viet Cong (VC) insurgency. Such

a concession, however, would have forced Hanoi to abandon its aspirations for a reunited

Vietnam under communist control. By contrast, Nixon sought a more modest policy

objective of “peace with honor,” a ceasefire which withdrew U.S. forces while leaving the

NVA in the South. Such a peace deal significantly shifted the balance of power in

Hanoi’s favor and set the conditions for the eventual fall of Saigon in April 1975.

A third argument posed by air power theorist Robert Pape focuses on the

differences in targeting between the Rolling Thunder and the Linebacker campaigns.5

Pape contends that Rolling Thunder failed because air strikes on North Vietnam’s

industrial infrastructure could not inflict sufficient pressure to convince Hanoi to abandon

its goal of reunification. Likewise, both Clodfelter and Pape note that Rolling Thunder

failed to interdict supplies to the NVA and VC fighters in the South because of the

minimal supply requirements for their guerilla operations. By 1972, however, the NVA

had transformed into a conventional army dependent on supply lines that were then

vulnerable to air attack.6

3 Admiral U.S. Sharp, Strategy for Defeat: Vietnam in Retrospect (Novato, CA: Presidio, 1978); General William Momyer, Airpower in Three Wars (Montgomery, AL: Air University Press, 2003) 4 Clodfelter, 148. 5 Pape, Bombing to Win, 176. 6 Clodfelter, 173; Pape, 200.


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Common to all three arguments is the assumption that the Linebacker I and II air

campaigns in North Vietnam played a central role in Hanoi’s decision to seek a peace

deal, an assumption that is fundamentally wrong.7 Recent scholarship on North

Vietnamese decision making and the author’s access to previously classified internal Air

Force assessments support an alternative interpretation of air power’s effectiveness as that

of directly attacking the NVA and defeating them in the Easter Offensive.8 In order to

make this argument, this article proceeds in four parts. The first section reviews air power

and coercion theory and the causal logic underpinning the United States’ punishment and

denial coercive strategies employed during the Vietnam War. Also examined are U.S. air

power doctrine and the distinction between attacking enemy armies directly with close air

support (CAS) and battlefield air interdiction (BAI), and the indirect approach of air

interdiction. In addition, specific air power technologies employed for CAS and BAI are

reviewed: tacair, B-52 Arc Light, and fixed- and rotary- wing gunships The second

section evaluates the impact of air power on the three major battles of the Easter offensive:

the fall of Quang Tri, the defense of An Loc, and the defense of Kontum. The outcomes

of all three battles were determined before Linebacker I could have had an impact on the

battlefield. This isolates the effect of CAS and BAI on the North Vietnamese deployed

forces. The third section evaluates Linebacker I and the impact it had on North Vietnam’s

resupply of the NVA fighting in South Vietnam. The final section assesses the role of air

power in the retaking of Quang Tri which directly led to Hanoi seeking a diplomatic 7 Sharp, 248; Clodfelter, 167; Pape 199. 8 Recent research includes Nguyen, Hanoi’s War; Randolph, Powerful and Brutal Weapons; Huyen, “Defeating the Americans”; Ha Dang, ed., Collected Party Documents translated by Merle Pribbenow (Hanoi: National Political Publishing House, 2004). U.S. Air Force reports declassified in October 2013 by the authors include HQ PACAF Evaluation Report for the NVN Offensive (April-August 1972) AFHRA K717.04-9 19720401-19720831; HQ Seventh Air Force Commanders’ Conference 18-19 July 1972 AFHRA K168.06-228 72/07/18-72/07/19; HQ Seventh Air Force History of Seventh Air Force 1 July 1972 – 29 March 1973, Volume I AFHRA740.01-25 1 July 72 – 29 Mar 73, v1.


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solution in October 1972.9 Also considered is the diplomatic maneuvering that delayed a

settlement and the impact Linebacker II had on the final agreement.

Coercion Theory and Air Power Doctrine

During the Vietnam War, the United States employed air power in an effort to

compel Hanoi to alter its policies towards South Vietnam. Coercion threatens force or

uses restricted force to convince an enemy to do one’s will.10 In On War, Carl Von

Clausewitz acknowledges coercion as an alternative to a brute force strategy, under which

disarming the enemy can “be replaced by two other grounds for making peace: the first is

the improbability of victory; the second is its unacceptable costs.”11 This insight forms the

basis for modern coercion theory, whereby making victory improbable is known as a

denial strategy and making costs unacceptable as a punishment strategy.12 In regard to

punishment, Thomas Shelling argues such a strategy works by imposing high expected

costs upon the target by “…the threat of damage, or of more damage to come.”13 A

successful punishment strategy signals the credible threat of future costs in order to

convince the enemy to concede now.

The Rolling Thunder air campaign in 1965 started as a punishment strategy known

as gradual escalation. The Johnson administration intended to take hostage targets highly

prized by Hanoi. Instead of attacking these sites, Johnson ordered strikes on military and

transportation targets along North Vietnam’s panhandle south of the 19th parallel.14 When

the air raids had compelled Hanoi neither to negotiate nor to withdraw support for the VC, 9 Nguyen, 270; Randolph, 325; Huyen, “Defeating the Americans.” 10 Carl Von Clausewitz, On War (Princeton: Princeton University Press, 1976), 77. 11 Ibid., 91. 12 Glenn Snyder, Deterrence by Denial and Punishment, Center of International Studies Research Monograph No.1, (Princeton: Princeton University, 1958). 13 Thomas Schelling, Arms and Influence (New Haven: Yale University Press, 1966), 3. 14 HQ PACAF (1966) CHECO Report, Rolling Thunder Mar-June 1965, 13a.


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Johnson approved additional bombing up to the 20th parallel. Upon the failure of these

attacks, he ordered air strikes still further north.15 In the end, five months of restricted air

strikes failed to compel Hanoi to forsake its goal of reunification. As a result, the United

States abandoned gradual escalation in favor of a denial strategy based on air interdiction.

Coercion by denial is an alternative to coercion by punishment.16 Whereas

punishment increases the costs an enemy expects to suffer, denial decreases an enemy’s

expected benefits for continuing to fight.17 A denial strategy succeeds by attacking the

enemy’s military capability. If the enemy can be convinced that its military strategy will

not work, that the situation is hopeless, then it has an incentive to concede and avoid

additional costs of fighting.18 While punishment threatens what the enemy values, denial

lowers the enemy’s probability of victory.

This was the goal when the United States adopted a denial strategy directly

attacking the NVA during the Easter Offensive in March of 1972 and attacking North

Vietnamese supply lines in the Linebacker I air campaign beginning in May. Prior to

evaluating and contrasting air power during these air operations, a brief review of U.S. Air

Force doctrine for attacking enemy armies is warranted. As a result of its experience in

World War II and Korea, by the Vietnam War the USAF had refined its Counterland

doctrine to include interdiction and close air support.19 Airmen defined interdiction as

“…the application of air fire power for the purpose of neutralizing, destroying or

15 Ibid., 39a; HQ PACAF (1967) CHECO Report, Rolling Thunder Jul 65 – Dec 1966, Figure 2; For more on Rolling Thunder see Pape, 181-2. 16 Jonathan Shimshoni, Israel and Conventional Deterrence: Border Warfare from 1953 to 1970 (Ithaca NY: Cornell University Press, 1988), 6; Pape, 18-19. 17 Pape, 18. 18 Pape, 17. 19 Air Force Manual 1-7, Theater Air Forces in Counter Air, Interdiction, and Close Air Support, 1 March 1954.


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harassing enemy surface forces, resources and lines of communication.”20 Air interdiction

(AI) missions indirectly attacked an enemy army by targeting its forces, LOCs, and

supplies deep inside enemy territory. Battlefield air interdiction (BAI), by contrast,

directly attacked the enemy’s fielded forces, LOCs, and supplies within the battle area. 21

The delineation between an AI and BAI mission was the bomb line.22 Beyond the bomb

line, air commanders selected targets, while missions inside the bomb line required

coordination with ground commanders. In addition to BAI, air power short of the bomb

line could also be employed as close air support (CAS). CAS placed even more controls

upon aviators than BAI as strikes required detailed coordination and clearance by the

friendly ground commander operating in close proximity to enemy forces.

All of South Vietnam and Route Pack 1 just north of the DMZ fell within the

bomb line.23 As such, U.S. air strikes within this territory were under the control of the

Military Assistance Commander Vietnam (MACV), U.S. Army General Creighton

Abrams, who had replaced General William Westmoreland by 1972.24

CAS and BAI: Tacair, B-52 Arc Light, and Gunships

The United States relied upon four air power technologies for BAI and CAS. First,

tactical aircraft (tacair) included an assortment of fighter-bombers flown by the U.S. Air

20 Tactical Air Command Manual 55-3, Joint Air-Ground Operation, 15. 21 Terrance McCaffrey, What Happened to Battlefield Air Interdiction? (Montgomery, AL: Air University Press, 2004), 15; Air Force Doctrine Document 2-1.3, Counterland Operations, 11 September 2006, 25. The Air Force removed the term battlefield interdiction from its doctrine 1966. In the 1980s the AirLand Battle concept reintroduced the term battlefield air interdiction which is why the battlefield air interdiction and the acronym BAI is used in this article. The Air Force eliminated the term BAI from doctrine prior to the 1991 Gulf War. 22 The bomb line is now referred to as the fire support coordination line (FSCL). 23 For deconfliction the U.S. Air Force and Navy divided North Vietnam into 6 sections called Route Packs. Route Pack 1 was the most southern and Route Packs 5 and 6 the most northern next to the Chinese border. 24 HQ PACAF Evaluation Report for the NVN Offensive (April-August 1972) AFHRA K717.04-9 19720401-19720831, V-1-2. In June 1972 Abrams was appointed Chief of Staff of the Army and he was replaced by General Frederick C. Weyand.


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Force, Navy, Marine Corps and the South Vietnamese Air Force (VNAF).25 These fast

jets carried an assortment of air-to-ground munitions.26 Tacair was most effective during

the day and under visual flight conditions when aircrew could visually identify targets or

be directed by forward air controllers (FACs) who located, identified and marked targets

for them.27 Tacair proved lethal against tanks, artillery and concentrated troops in the

open.

Tacair could operate in high threat environments where the North Vietnamese

operated SA-2 surface-to-air radar-guided missiles and MiG air to air interceptors. As a

result, tacair could be employed where B-52s, gunships, and airborne FACs could not, just

north of the DMZ in Route Pack 1 and just south of it in Military Region I (MR I).28

Because of its survivability and versatility, tacair was also tasked with penetrating deep

inside North Vietnam’s air defenses in the Rolling Thunder and Linebacker I and II air

campaigns.

While tacair was most effective during the day, B-52 Arc Light missions offered

distinct advantages for night and all-weather CAS and BAI. The B-52 arrived in

Southeast Asia in 1965. Vulnerable to SA-2s and MiG interceptors, the B-52s did not

participate in the Rolling Thunder air strikes aimed deep into North Vietnam. General

25 These included A-4s, A-6s, A-7s, F-4s, F-100s, and F-105s. 26 Weapons included general purpose and laser-guided bombs, rockets, napalm, and cluster bombs. 27 Forward observers employed handheld lasers to guide precision bombs dropped by tacair against armor and artillery HQ Seventh Air Force, The U.S. Air War Against Tanks, AFHRA K740.041-2 20 May 1973, ii; HQ Seventh Air Force, US Air Forces vs The 130MM Field Gun April-November 1972, AFHRA K740.041-1 Apr-Nov 1972, ii. During the Easter offensive the USAF reported 389 tanks destroyed and another 289 damaged from laser guided bomb strikes. HQ Seventh Air Force, The U.S. Air War Against Tanks, 28. 28 From 31 March 31 to 23 October 1972 the U.S. Air Force, Navy, Marine Corps and Vietnamese Air Force conducted over 18,000 strikes in Southeast Asia (North and South Vietnam, Cambodia and Laos), of which 94% were flown as CAS or BAI missions. 16,000 of these missions were flown south of the DMZ in South Vietnam, Laos and Cambodia, while another 1,000 were conducted just north of the DMZ in Route Pack 1 (RP 1). Still further north, another 1,250 missions were flown in the North Vietnamese panhandle in RP II, III and IV between the 18th and 20th parallel, and 360 strikes were conducted north of the 20th parallel, near Hanoi, Haiphong and the Chinese border. THOR DATABASE 31 March 1972 – 23 October 1972, courtesy of Jenns Robertson, USAF LtCol (ret).


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Westmoreland instead utilized the heavy bombers for BAI throughout South Vietnam and

across the border into Laos, Cambodia and Route Pack 1.29 B-52 airstrikes packed a

punch as a three-ship formation could spread up to three hundred and twenty 500-pound

general purpose bombs over an area of one-by-two kilometers.30

By the Tet offensive, the B-52 Arc Light missions had proven lethal against

concentrations of enemy troops in the open. Arc Light was the code name for missions

flown under control by one of the five ground-based radars distributed throughout South

Vietnam and Thailand. By 1972, B-52 Arc Light missions had become accurate enough

to employ within a kilometer of friendly positions, which made them capable of night and

all weather CAS.31

A single B-52 bomb run could destroy most of the supplies and troops within its

vast bomb pattern. While previously the NVA and VC had by tunneling been able to

negate B-52 strikes, in the Easter offensive NVA units on the march were caught in the

open, rendering them more vulnerable to air attack.

For all its capability, the B-52 did have limitations. First, air strikes were only as

effective as the quality and timeliness of available intelligence. Second, the NVA reacted

to B-52 strikes by dispersing troops and supplies to decrease the effectiveness of their

strikes. This increased the survivability of troops but also made it more difficult for the

29 William Head, War from above the Clouds (Maxwell AFB, AL: Air University Press, 2002), 18, 29. 30 To increase the bomb load, the older B-52D models were modified to carry 108 conventional 500lb bombs. The B-52G models had internal fuel cells which increased range but, as a result, could carry only 27 conventional bombs, just double that of an F-4 load out. Head, 22. 31 From 31 March to 23 October 1972 B-52s flew 6,000 missions, 88% south of the DMZ, 10% in RP 1, and fewer than 2% north of RP 1. Missions consisted of three B-52 sorties. The missions in RP 1 occurred after July once SA-2s had been suppressed. Two sources on the B-52 missions have total missions between 5,600 – 6,600, the lower number coming from the THOR database from 31 March 1972 – 23 October 1972 and the higher figure from the HQ PACAF Summary Air Operations Southeast Asia volumes from April to October 1972 AFHRA K717.3063 April – Oct 1972.; HQ PACAF, Evaluation Report for the NVN Offensive (April-August 1972) AFHRA K717.04-9 19720401-19720831, VII-1. For additional details on the development of Arc Light tactics, see HQPACAF CHECO ARC LIGHT: June 1967-December 1968.


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NVA to concentrate in order to conduct offensive operations. Third, B-52 air strikes,

while lethal against soft targets, were less so against armor and artillery.32 As such, the B-

52 was best suited for area targeting.

A third weapons system developed during the Vietnam War was the fixed-wing

gunship. The USAF began by converting cargo planes into gunships, first with the AC-

47, then the AC-119, and finally the AC-130.33 These gunships took advantage of a

unique operating method for which the pilot used a pylon turn to train a battery of laterally

mounted guns on a specific target. The pylon turn enabled the pilot to adjust fires in close

proximity to friendly forces.34 By 1972, over two dozen AC-119s and AC-130s operated

in Southeast Asia.35 The AC-130 proved most effective against NVA conventional

forces.36 The gunship was armed with a 40mm cannon and in early 1972, the first AC-130

was upgraded with a 105mm cannon, giving the aircraft an improved anti-armor

capability. Its low-light television and infrared sensors combined with its digital fire

control computer and inertial navigation system to make the AC-130 adept at night

operations.37 From 1968 to 1972, during the Commando Hunt interdiction campaigns

along the Ho Chi Minh Trail, the AC-130 earned a reputation as a truck killer. In the

Easter Offensive, during the battles of An Loc and Kontum, the gunship was relied upon

for CAS as it could loiter for prolonged periods over friendly positions and provide

32 HQ MAC-V The Nguyen Hue Offensive MACDI Study 73-01 12 January 1973, 8. 33 For a detailed history of the development of fixed wing gunships, see Jack Ballard, Development and Employment of Fixed-Wing Gunships (Washington, D.C.: Office of Air Force History, 1982). 34 Ballard, 2. 35 Lavalle, Airpower and the 1972 Spring Invasion, (Washington, D.C.: Office of Air Force History, 1985) 30. 36 From April to June, AC-130s conducted 1,117 combat sorties in South Vietnam, Laos and Cambodia with 55% of the missions providing CAS for troops-in-contact situations. History of the 8th TAC Fighter Wing, v1 “Narrative”, AFHRA K-WG-8-H1 Apr-Jun 1972, v.1, 16, 18, 19. 37 HQ PACAF Evaluation Report for the NVN Offensive (April-August 1972) AFHRA K717.04-9 19720401-19720831, VI 2-3.


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precise, around-the-clock firepower during the most critical days and nights of the

battles.38 Though the AC-130 could safely operate above small arms fire, it was

vulnerable to surface-to-air missiles and anti-aircraft artillery (AAA). The loss of an

aircraft near the DMZ on 28 March 1972 prompted the gunships to we withdrawn from

operations near Quang Tri.

The fourth weapon system developed by U.S. Army aviation entailed precision-

guided weapons mounted on rotary-wing gunships. In 1972, the Army combined Tube-

launched Optically-tracked Wire-guided (TOW) missiles aboard UH-1B Huey helicopters.

With the start of the Easter Offensive, the Army saw an opportunity to test the Huey

gunship and on 24 April, two modified aircraft and three TOW systems arrived in Saigon.

The crews soon had the gunships operating in the Central Highlands at Kontum, where

they proved lethal in a reduced threat environment without AAA or SA-7 infrared-guided

surface-to-air missiles.39 The TOW mounted gunship had several distinct advantages. Its

extended range of over 2,500 meters along with its weapons reliability and precision

provided a potent tool for destroying armor and point targets.40

The next section evaluates how the U.S. employed these weapon systems in the

three major offensives launched by the NVA at the outset of the Easter offensive.

Air Power in the Easter Offensive In 1968, following the operational defeat of the NVA and VC in the Tet Offensive,

Hanoi began reconstituting its forces in the South. In response, the USAF conducted a 38 History of the 8th TAC Fighter Wing, v1 “Narrative”, AFHRA K-WG-8-H1 Apr-Jun 1972, v.1, 24. HQ PACAF Evaluation Report for the NVN Offensive (April-August 1972) AFHRA K717.04-9 19720401-19720831, VI-1. 39 Major John Burns, XM-26 TOW: The Birth of the Helicopter as a Tank Buster (Quantico: United States Marine Corps Command and Staff College, 1994), 15-17; In 41 days operating in MR II, the two Huey gunships reported destroying 47 targets including 24 tanks, Burns 75-77. 40 The UH-1B/Tow combination was 93% reliable and 82% hits of the reliable launches. Burns, 90.


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series of seasonal air interdiction campaigns into Laos, known as Commando Hunt, with

the objective of curbing the flow of men and supplies transiting the Ho Chi Minh Trail. In

1970, U.S. and ARVN (Army of the Republic of Vietnam) troops crossed into Cambodia

to cut enemy LOCs to the port of Sihanoukville and deny sanctuary for NVA units

threatening the southern Military Regions III (including Saigon) and IV (the Mekong

Delta) in South Vietnam.

The operational success of the joint U.S./ARVN operations in Cambodia

encouraged U.S. commanders to propose a more ambitious ARVN ground offensive in

Laos to cut the Ho Chi Minh Trail.41 The resulting operation, Lam Son 719, was launched

in late January 1971 to disrupt the NVA buildup adjacent to MR I in the western Quang

Tri province and prove the mettle of the ARVN.42 Unfortunately for U.S. military

operations, the domestic blowback from the invasion of Cambodia had led to a legal

prohibition on the employment of U.S. ground forces outside the Republic of Vietnam.

As a result, the 20,000 ARVN troops of the Lam Son 719 raid would enjoy ample U.S. air

support but would advance without the direct support of U.S. combat troops or advisors.

While the first week of the operation was encouraging, the raid stalled as South Vietnam’s

President Thieu sought to limit ARVN casualties and the NVA concentrated over 60,000

troops to cut the ARVN salient into Laos.43 After 45 days in Laos, the ARVN units

withdrew. For the ARVN, the results of Lam Son 719 were Pyrrhic at best; while they

had managed to destroy numerous NVA stockpiles, the heavy losses and the mixed

41 Brig. Gen. Tran Dinh Tho, The Cambodian Incursion (Washington, D.C.: U.S. Army Center of Military History, 1979); James H. Willbanks, Abandoning Vietnam: How America Left and South Vietnam Lost its War (Lawrence: The University Press of Kansas, 2004), 83-86. 42 Robert Sander, Invasion of Laos 1971: Lam Son 719 (Norman: University of Oklahoma Press, 2014). 43 James H. Willbanks, A Raid Too Far: Operation Lam Son 719 and Vietnamization in Laos (College Station: Texas A&M Press, 2014), 168.


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performance of the South Vietnamese units undermined ARVN morale and drew into

question the efficacy of Vietnamization. Though the NVA lost over 20,000 troops to U.S.

air power and ARVN firepower, the North Vietnamese emerged from the Laotian

campaign emboldened.44

The North Vietnamese decision to launch the Easter Offensive in 1972 was a

reaction to an array of opportunities and threats. The failure of Lam Son 719 suggested

that a major conventional offensive against the ARVN might succeed. The steady

withdrawal of U.S. ground forces meant that the ARVN would have to fend for itself.

Still, there were reasons for the North to fear that this window of opportunity might be

closing. In the aftermath of the Tet offensive of 1968, the United States and their ARVN

allies had been increasingly successful in suppressing VC resistance in the south. Nixon’s

successful overtures to the Chinese and his pursuit of détente with both the Chinese and

Russians jeopardized North Vietnam’s ties with its two sponsors. Unless the North moved

swiftly to topple its neighbor, it faced the prospect of a stronger Saigon and diminishing

support from its Communist patrons.

Recent research on Communist decision making suggests that it was North

Vietnamese leaders Le Duan and Le Duc Tho who championed a major, conventional

offensive to resolve these dilemmas. At a minimum, such an offensive would upset the

Nixon Administration’s progress in isolating the regime from its sponsors; at best it might

break the ARVN and trigger the southern uprising the North had failed to achieve in

1968.45 Having decided on an invasion, the NVA’s next step was to translate these

abstract goals into concrete military objectives. The destruction of large ARVN units and

44 Ibid., Willbanks, A Raid Too Far, 154, 162-163, 188. 45 Lien-Hang T. Nguyen, Hanoi’s War (Chapel Hill: The University of North Carolina Press, 2012), 232-234.


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the seizure of major cities and towns were seen as ways to shatter Vietnamization,

strengthen the North’s hand in the Paris negotiations, and precipitate the collapse of the

southern regime.46

To accomplish these sweeping goals, the North Vietnamese committed 14 of its 15

divisions and 26 separate regiments, a total of between 130,000 and 150,000 troops.

These units were equipped with new Soviet conventional equipment to include 1,200

tanks and armored fighting vehicles, long-range artillery, advanced air defense systems,

and anti-tank guided missiles.47 The NVA forces would attack on three separate axes: the

main attack across the DMZ in MR I, a second attack from Cambodia towards Saigon in

MR III, and a third attack from Laos and Cambodia into the Central Highlands of MR II

(See Map I).48 A breakthrough on any of these axes would be fatal; the wide distribution

of these attacks forced the South Vietnamese to divide their attention and resources. On

each of these axes the North Vietnamese planned to combine long range, heavy artillery

preparations with the shock of tank attacks to shatter ARVN resistance and produce a

breakthrough that could be exploited by its infantry and mechanized formations.49

46 Ibid., Willbanks, Abandoning Vietnam, 124-127; The Nguyen-Hue Offensive, MACDI Study 73-01, 12 January 1973, C-1. 47 Thomas P. McKenna, Kontum: The Battle to Save South Vietnam (Lexington: The University Press of Kentucky, 2011), 60-61; ibid., Willbanks, Abandoning Vietnam, 127. 48 For a discussion of North Vietnamese debates over the main effort, see Lien-Hang Nguyen, Hanoi’s War, 245. 49 Lam Quang Thi, The Twenty-five Year Century (Denton: University of North Texas Press, 2001), 266-267; Jack S. Ballard, Development and Employment of Fixed Wing Gunships (Washington: Government Printing Office, 1982), 236.


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MAP 1: South Vietnam and the Easter Offensive50

On paper, the ARVN was a large, robustly equipped, and reasonably well-trained,

army. On the eve of the invasion, the ARVN fielded 11 infantry divisions, 58 artillery 50http://www.westpoint.edu/history/SiteAssets/SitePages/Vietnam%20War/vietnam%20war%20map%2033.jpg accessed 30 Apr 2015.


18

battalions, and 19 armor battalions. The 550,000 men of the Regional Forces and Popular

Forces provided manpower for the defense of South Vietnam. This otherwise impressive

force faced four problems. First, the removal of U.S. ground troops had led to an

inevitable thinning of the defensive lines. In MR I, the target of the North Vietnamese

main effort, 80,000 U.S. troops had been replaced by 25,000 ARVN troops holding much

of the same ground.51 Second, the geography of South Vietnam gave the North

Vietnamese an opportunity to strike at multiple points from its sanctuaries and left the

ARVN with no easily defensible frontiers or strategic depth. Third, the quality of the

ARVN leadership varied widely; President Thieu’s struggle to maintain power and

preserve the Republic of Vietnam led to countless political compromises that put political

generals in critical positions. Fourth, the ARVN had been focused almost exclusively on

counterinsurgency rather than conventional warfighting. While this had contributed to

impressive gains in pacification between 1968 and 1972, it meant that the ARVN lacked

experience in combined arms warfare.52

While the United States had removed almost all of its ground forces by late March

1972, the U.S. advisory command (MACV) and air forces remained in place. The senior

U.S. commander, General Creighton Abrams, recognized the North Vietnamese buildup in

the fall of 1971. He correctly assessed that the attack would be a massive affair and the

ultimate test of Vietnamization.53 Abrams’ plan was to use the North Vietnamese

offensive as an opportunity to focus U.S. firepower and inflict overwhelming damage on

51 Lt. Gen. Ngo Quang Truong, The Easter Offensive of 1972 (Washington, D.C.: U.S. Army Center of Military History, 1977), 16. 52 Ibid., 166. 53 Lewis Sorley (ed.), Vietnam Chronicles: The Abrams Tapes (1968-1972) (Lubbock: Texas Tech University Press, 2004), 729, 733-734, 740-741, 745-56, 775, 803.


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the North.54 The records of Abrams’ staff meetings in late 1971 and early 1972 reveal a

clear anticipation of the centrality of U.S. air power and particularly the power of B-52

Arc Light missions inside South Vietnam. He was equally adamant that such fires be

targeted by U.S. advisors or Forward Air Controllers (FACs):

“You know, air is really very good if you’ve got a way of putting it on the enemy, and it’s always really tied down to that – some guy out there that can see them, or knows where they are, and if he’s got communications to a FAC, you’re in business. And if you haven’t got that, if you haven’t got that, you’re going to wind up bombing trees.”55

Stripped of U.S. ground forces, Abrams planned to use the B-52s as his mobile reserve

and the U.S. advisors as his eyes to break the impending North Vietnamese onslaught.56

Commando Hunt VIII, conducted over the winter of 1971-72 did not stop the

deployment of enemy forces but did delay the NVA’s timetable. As a result, Hanoi

slipped the start date for invasion until the end of March and, in order to take advantage of

shorter supply lines, shifted the primary front from MR III near Saigon, to MR I next to

the DMZ.57

The following section evaluates the impact U.S. air power had on the outcomes of

the three major battles which occurred at the onset of the Easter offensive: the fall of

Quang Tri near the DMZ, the defense of An Loc near Saigon, and the defense of Kontum

in the Central Highlands. These battles were decided before the Linebacker I air

interdiction campaign could have had an impact on their outcomes. As such, the effects of

air power were limited to direct attacks by CAS and BAI on the NVA’s fielded forces. At

An Loc and Kontum, U.S. air power played a key role in stopping the NVA’s offensive

54 Ibid., 568, 779, 782. 55 Ibid., 784. 56 Ibid., 782, 807. 57 Truong, 13.


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and destroying large portions of the Communist army. The fall of Quang Tri, however, is

the story of the failure of U.S. air power to stop the NVA advance.

The Battle in the North: MR I and the Fall of Quang Tri

On 30 March, 1972, the Communist offensive in MR I opened with a massive

artillery preparation aimed at ARVN positions south of the DMZ. The ARVN forces were

spread across a series of firebases originally established by the Americans to support the

counterinsurgency and stave off attacks from the Laotian sanctuaries to the west.58 Taking

advantage of the longer range of their artillery, the NVA fired over 5,000 rounds of

artillery and rocket fire in the first 24 hours of the attack.59 These fires largely silenced

the ARVN artillery arrayed across the 12 northern firebases, allowing NVA infantry

forces to encircle those isolated posts. The 40,000 troops of the 304th and 308th divisions

and three separate infantry regiments, supported by 200 tanks, enveloped the ARVN front

line positions from the north and the west.60

The defenders in MR I were unprepared for an assault of this scale and intensity.

The guardian of the northern defenses was the newly formed ARVN 3rd Division,

numbering roughly 11,000 men.61 Before the offensive, the ARVN command had been

confident that their artillery and U.S. air power would be sufficient to defeat any assaults

launched across the open terrain south of the DMZ.62 While this was plausible, the 3rd

Division had no detailed defensive plan to respond to such a conventional invasion.63 To

58 Ibid., Lam Quang Thi, 267; ibid., McKenna, 64. 59 Col. G.H. Turley, The Easter Offensive: Vietnam, 1972 (Novato: Presidio Press, 1985), 46-47, 65; ibid., McKenna, 63. 60 Ibid., Willbanks, Abandoning Vietnam, 127. 61 Ibid., Turley, 23. 62 Ibid., Turley, 29; ibid., Truong, 22-23. 63 Ibid., Turley, 50; ibid., Truong, 20.


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make matters worse, the division had ignored specific invasion warnings from its own

Joint General Staff and was instead engaged in a rotation of two of its three regiments on

the day of the North Vietnamese attack.64

A successful forward defense would have required the timely application of

overwhelming artillery and air power and robust ARVN resistance on the ground. For

several reasons, neither of these came to pass. First, the NVA artillery attack destroyed or

silenced the ARVN artillery; without the use of their artillery, the ARVN were unable to

defend the firebases, fire on the attacking columns, or suppress the NVA artillery.

Second, bad weather prevented the use of any significant tactical air support in the first

week. During this critical period, the only sources of fires were [unobserved and radar

controlled] B-52 Arc Light missions and naval gunfire from U.S. destroyers offshore.

Third, the Communists had moved substantial air defenses including SA-2 radar-guided

missiles into the forward area; these defenses led to the withdrawal of vulnerable U.S. and

Vietnamese aircraft to include fixed-wing gunships. And finally, as part of the

Vietnamization process, the United States had removed its Tactical Air Control System

(TACS) from MR I. For the first month of the invasion, difficulties in coordinating

observers, aircraft, and artillery severely limited the effectiveness of U.S. and ARVN

firepower employed in the north.

Under such adverse conditions, the forward ARVN line began to crumble on the

second and third days of the offensive.65 Once the line of forward fire bases had been

breached, the ARVN scrambled to establish a defensive line along the Cua Viet river

anchored around the town of Dong Ha north and west of Quang Tri City. North

64 Ibid., Turley, 30. 65 Ibid., Turley, 73.


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Vietnamese difficulties in coordinating their armored assault and delays in moving their

own artillery forward led to a temporary pause in the Communist advance. General Lam,

the senior ARVN commander in the north, took this as an opportunity to launch a

counteroffensive on April 14, Operation Quang Trung 729. Unfortunately, Lam lacked

the reserves, air power, and coordination to make any substantial advance against the

numerically superior NVA forces; instead, the offensive further weakened the 3rd

Division’s defenses and set the stage for the final ARVN collapse in Quang Tri province.66

On April 27, the NVA renewed their attack with another massive artillery barrage

followed by a tank attack. Once again, weather severely limited the effectiveness of U.S.

and South Vietnamese tactical air support. The ARVN were driven back from the Cua

Viet river and were encircled in the provincial capital of Quang Tri. A flurry of

contradictory orders from General Lam first to withdraw and then to hold in place

contributed to the disintegration of the defenses of Quang Tri and a pell-mell retreat

towards Hue. By May 2, the ARVN 3rd Division had been destroyed and the entire

province of Quang Tri was in Communist hands.67

The collapse at Quang Tri led General Abrams to intercede with President Thieu

and demand the removal of General Lam and his replacement by Lieutenant General

Truong.68 Truong’s prompt moves to prepare a new defensive line along the My Chanh

River north of Hue and the A Shau valley in the west marked the end of the Communist

advance in MR I.69 The ARVN losses during the month of withdrawal had been severe.

In addition to the disintegration of the 3rd Division, the South Vietnamese had suffered

66 Dale Andrade, America’s Last Vietnam Battle: Halting Hanoi’s 1972 Easter Offensive (Lawrence: University Press of Kansas, 2001), 106; ibid., Truong, 36-37. 67 Ibid., Andrade, 145. 68 Ibid., Andrade, 141-142. 69 Ibid., Lam Quang Thi, 279; ibid., Willbanks, Abandoning Vietnam, 149.


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50% casualties in its ranger units and had lost 140 artillery pieces and over 200 armored

vehicles.70

Air Power and the Fall of Quang Tri

The South Vietnamese Air Force (VNAF) maintained a fleet of light, fixed-wing,

propeller-driven, O-1 forward observation aircraft, along with A-1 and A-37 attack aircraft

to provide CAS and BAI for MR I. The VNAF was quickly overwhelmed, however, by

the magnitude of the NVA’s offensive and the lethality of its air defenses. As a result, the

ARVN relied on U.S. air support. At the outset of the invasion, the USAF had over 180

forward air controllers (FACs), 200 tactical aircraft (tacair), 23 fixed-wing gunships, and

thirty B-52 bombers deployed to South Vietnam, Thailand, and Guam.71 In April and

May of 1972, additional deployments brought the number of Air Force and Marine Corps

tacair up to 417 fighter-bombers and 171 B-52s.72 In addition, the U.S. Navy deployed

180 tacair aboard two carriers in the Gulf of Tonkin. This number doubled in early April

with the addition of two more carriers and a total of six carriers were available by early

June.73 The U.S. air order of battle by May totaled over 600 tacair, 171 B-52s, and 28

fixed-wing gunships, a force sufficient to provide air support for Quang Tri, An Loc, and

Kontum.74

70 Ibid., Truong, 61. 71 Lavalle, 39; HQ PACAF Evaluation Report for the NVN Offensive (April-August 1972) AFHRA K717.04-9 19720401-19720831, III-7, IV-1. 72 HQ Seventh Air Force History of Linebacker I Operation 10 May 1972 – 23 Oct 1972, AFHRA K740.04-24 72/05/10-72/10/23, Figure 3; HQPACAF Summary Air Operations in Southeast Asia, Volume XCIII April 1972, AFHRA K717.3063 April 1972, 2-7. 73In June the Saratoga and Midway increased the total to 6 carriers. John Sherwood, Nixon’s Trident: Naval Power in Southeast Asia, 1968-1972 (Washington, D.C.: Naval History & Heritage Command, 2009), 36. Peter Mersky and Norman Polmar, The Naval Air War in VIETNAM, 2nd Edition (Baltimore: Nautical and Aviation Publishing Co of America, 1986), 195,197. 74 HQ Seventh Air Force History of Linebacker I Operation 10 May 1972 – 23 Oct 1972, AFHRA K740.04-24 72/05/10-72/10/23, Figure 3; HQPACAF Summary Air Operations in Southeast Asia, Volume XCIII April 1972, AFHRA K717.3063 April 1972, 2-7.


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Even the influx of tacair, B-52s, and gunships with the resultant increase in CAS

and BAI sorties could not prevent the fall of Quang Tri during the early stage of the Easter

Offensive. This was primarily due to three reasons: bad flying weather in MR I, NVA air

defenses deployed along the DMZ, and an ineffective VNAF tactical air control system

(TACS). First, the NVA timed the invasion to take advantage of poor visibility and low

cloud ceilings. This adversely affected the employment of tacair and gunships. The local

weather in Quang Tri during the first two weeks of the offensive was particularly harsh

with continuous heavy rain and cloud cover. Conditions near the DMZ were far worse

than further south in MR II and III.75 The NVA concentrated and maneuvered its armor

and troops with immunity across territory otherwise vulnerable to air attack. All-weather

B-52 Arc Light strikes were employed to some effect but were hampered by the lack of

accurate and timely coordinates. U.S. naval gunfire was also used against targets near the

coast, but its effectiveness was hampered by the poor weather that precluded the

adjustment of fires by forward observers. By the time the weather improved in mid-April,

the impact of additional air attacks on the NVA assault proved to be too little, too late.

Second, the NVA significantly increased the surface-to-air threat in MR I by

relocating SA-2 radar-guided missiles near and, in some cases, across the DMZ and by

deploying large numbers of medium and heavy anti-aircraft artillery (AAA). During the

first weeks of the invasion, the NVA fired 1,000 SA-2 missiles near the DMZ.76 As a

result, fixed-wing gunships could no longer operate near Quang Tri. The threat

environment also proved lethal for low and slow flying FACs, now unable to effectively

75 PACAF Summary Air Operations Southeast Asia volume XCIII April 1972, AFHRA K717.3063 April 1972, 6-2; Truong, 38. 76 8th Tactical Fighter Wing, History of the 8th TAC Fighter Wing, 1 April through 30 June 1972, Supporting Documents AFHRA K-WG-8-HI Apr-Jun 1972, V.2.


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locate targets or control tacair strikes near the DMZ.77 Even the high-flying B-52s were

restricted from operating north of Quang Tri City after one was struck by an SA-2

missile.78 Tacair continued to operate in Military Region I and Route Pack 1, but not

without taking its own losses as seven jets were downed by NVA air defenses in April.79

Third, U.S. air power proved ineffective in the defense of Quang Tri as a result of

the Vietnamization of the tactical air control system (TACS). Unlike weather or enemy

air defenses, this factor was within U.S. control. The TACS was the organization

responsible for integrating air power to support friendly ground forces. The TACS in

South Vietnam consisted of three levels. Overall responsibility for allocating air power in

South Vietnam fell to the Tactical Air Control Center (TACC) based near Saigon and

manned by USAF and VNAF personnel. The TACC planned and coordinated air

operations, and directed and, when necessary, diverted air assets to the four military

regions. The second level of air control were the Direct Air Support Centers (DASCs) in

each of the military regions. DASCs were tasked with distributing air assets to ground

units based on air requests. For this role, they had direct radio contact with aircraft that

checked in to verify missions or be diverted to higher priority/urgent requests. The third

level of air control were the tactical air control parties (TACPs) assigned directly to

ARVN units. TACPs consisted of Air Liaison Officers (ALOs), responsible for

coordinating and initiating air strike requests, along with ground and airborne Forward Air

77 Ibid., 24. 78 HQ PACAF Summary Air Operations Southeast Asia volume XCIII April 1972, AFHRA K717.3063 April 1972, 2-7. 79 Seven jets were downed by NVA air defenses in April. Ibid., 4-1.


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Controllers (FACs) who identified and marked targets and provided clearance for air

strikes. 80

By the end of 1971, the VNAF had assumed responsibility for the DASC in MR I,

responsible for supporting the ARVN 3rd Division. By contrast, the transition to VNAF

control of the DASCs in MR II and III was not scheduled to take place until June 1972.81

From the outset, the Vietnamese DASC had the daunting task of handling the influx of

hundreds of U.S., English-only speaking aviators crowding the skies and airwaves. The

job proved impossible, however, because of the poor coordination between the VNAF Air

Liaison Officer (ALO) and the 3rd ID planning staff and the ineptness of VNAF forward

air controllers (FACs). Inadequate equipment and training left the FACs unable to

perform the critical task of visual reconnaissance (identifying targets and providing

updated battlefield intelligence) and of air strike control (providing terminal strike control

for CAS).82

Problems with both the ALO and FACs can be traced back to the rapid expansion

of the VNAF as a result of Vietnamization. A shortage of qualified pilots left many ALO

billets vacant or manned by junior ranking, inexperienced officers. Also, unlike the

experienced American FACs, VNAF FACs were not pilots but observers who flew

alongside inexperienced pilots assigned to fly O-1 observation aircraft. The breakdown of

the TACS in MR I meant the VNAF could not effectively coordinate air strikes nor could

the FACs effectively employ tacair even when the weather allowed.83 Not until June,

80 HQ PACAF CHECO Vietnamization of the Tactical Air Control System (23 September 1974), 2-9. 81 Ibid., 44-6. 82 Ibid., 75-77. 83 Ibid., 23-29.


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following the fall of Quang Tri, was a U.S. TACS reintroduced to MR I, a move which

proved critical to the retaking of Quang Tri.

The fall of Quang Tri is the story of the inability of the United States to use its

firepower to compensate for the weakness of its ally. The defense at An Loc and Kontum

considered next, however, demonstrate the decisive role U.S. air power played when not

constrained by weather or air defenses and when operating with a functional tactical air

control system.

The Battle in the South: MR III and the Siege of An Loc

The NVA attack in Military Region III was a direct thrust from the Cambodian

sanctuaries down Route 13 towards Saigon. After a feint towards the more densely

populated Tay Ninh Province, the NVA sought to destroy the northernmost ARVN

stronghold at Loc Ninh and then isolate and destroy the ARVN position at An Loc.84 If

the NVA could succeed in capturing An Loc, they would have 47 miles of open road to

the capital of Saigon.85 The Communists committed 35,000 troops of three infantry

divisions, one artillery division, and a tank regiment to this drive on the capital.86

The ARVN 5th Division and its supporting elements stood in the way of the NVA

breakthrough. Two battalions of infantry and two batteries of artillery were located at Loc

Ninh; the remainder of the ARVN troops were located just south in An Loc or spread

across a handful of fire support bases on the northern and western flanks of Binh Long

province.87 As the attack unfolded, the Province Chief Tran Van Nhut, would commit an

84 Lam Quang Thi, Hell in An Loc (Denton: The University of North Texas Press, 2009), 41-42; ibid. Truong, 112. 85 Military Assistance Command Vietnam, Command History, March 1972- March 1973, Volume II, J-3. 86 James H. Willbanks, The Battle of An Loc (Bloomington: The Indiana University Press, 2005), 33. 87 Ibid., Willbanks, 30-31, 44.


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additional 2,000 Regional Force and Popular Force units to the defense of An Loc,

bringing the total force inside An Loc to 6,200 Vietnamese troops and 25 U.S. advisors.88

While the April 2 NVA feint at the ARVN firebases to the west in Tay Ninh

province inflicted heavy losses on the ARVN defenders, intelligence soon indicated that

the main thrust of the attack would come in Binh Long province along Route 13.89 On

April 5, the 5th VC division struck the Loc Ninh position with heavy artillery, tanks, and

infantry. U.S. advisors brought continuous tacair, Cobra helicopter, and fixed-wing

gunship attacks to break the first Communist assaults. While the ARVN resistance and

aerial firepower held the Communists off for three days, these measures were ultimately

insufficient to hold off the mass of the NVA attackers. As the U.S. advisors and U.S.

forward air controllers (FACs) sought to apply the array of CAS fires, the complexity of

orchestrating artillery, tacair, attack helicopters and fixed-wing gunships severely tested

the ground and air controllers.90

The stubborn resistance at Loc Ninh had bought time for the defenders of An Loc

to organize their defense. The Senior U.S. Adviser in MR III, General Hollingsworth, was

confident that U.S. firepower could offset the massive numerical advantage of the

attackers:

“Once the Communists decided to take An Loc, and I could get a handful of soldiers to hold and a lot of American advisors to keep them from running off, that’s all I needed. Hold them and I’ll kill them with air power; give me something to bomb and I’ll win.”91

88 General Tran Van Nhut, An Loc: The Unfinished War (Lubbock: The Texas Tech University Press, 2009), 110-111. 89Dale Andrade, America’s Last Vietnam Battle (Lawrence: The University of Kansas Press, 2001), 350. 90 Ibid., Willbanks, The Battle of An Loc, 50. 91 LTG Hollingsworth as quoted in Willbanks, The Battle of An Loc, 66.


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This then was the formula that would define U.S. efforts in all the defensive battles of the

Easter Offensive. ARVN troops willing to fight, supported by U.S. ground advisors,

FACs, and a TACS system, could use massive CAS and BAI to repel and eventually

destroy the mechanized formations that outnumbered them by more than three to one.

The first ground assault on An Loc came on April 13. The ARVN defenders, by

now cut off from Lai Khe to the south by the NVA 7th Division, were subjected to a 7,000-

round, fifteen-hour artillery barrage; this was followed by an attack by two regiments of

infantry and two dozen T-54 and PT-76 tanks.92 The ARVN defenders were dug in in the

town center, a rectangular perimeter measuring 2km-by-1km; throughout the day, they

repelled the attacking tanks and infantry with small arms and M-72 LAW anti-tank

rockets.93 Once again, U.S. and Vietnamese air support was decisive in stopping the NVA

advance. Having lost almost all of their artillery to NVA counter-battery fire, the

defenders were entirely dependent on air power for their defense.

Building on the experience at Loc Ninh, U.S. advisors and FACs applied the range

of air platforms in layers to defeat the NVA attack. B-52s were used against enemy

staging and assembly areas while U.S. and VNAF tacair delivered air strikes closer to the

perimeter. The closest fires were delivered by the rocket firing, AH-1 Cobra helicopter

gunships augmented by the continuous presence of AC-119 and AC-130 gunships.94 U.S.

advisors multiplied the number of sorties over An Loc by using a forward base at Bien

92 HQ PACAF Directorate, Tactical Evaluation Division CHECO Division, Battle for An Loc (5 April-26 June 1972), pp. 16; ibid., Willbanks, The Battle of An Loc, 72. 93 Ibid., Willbanks, The Battle of An Loc, 28. 94 Ibid., Willbanks, The Battle of An Loc, 77-78.


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Hoa for rearming and refueling tacair from carriers and airbases across Thailand and

South Vietnam.95

After two days of heavy attacks, the Communists had seized the northern half of

An Loc at a terrible cost. They had lost 23 tanks and countless infantry and these losses

forced them to regroup.96 Brigadier General Giffert, the number two U.S. advisor in MR

III, was blunt in his assessment of this first wave: “I really believe that without these [B-

52 Arc Light strikes and pre-planned tacair] the city would have fallen, because I think the

infantry would have gotten in with the tanks.”97 As they weathered the first Communist

assaults, the ARVN received critical reinforcements on April 14 as the ARVN 1st

Airborne Brigade was successfully inserted by helicopter onto the high ground south of

the town.98

The NVA renewed their assault on April 19 with simultaneous thrusts at the

Airborne units in the south and the 5th Division positions inside the town. After fierce

resistance, the Airborne troops were driven off the southern high ground and lost their

artillery in the process, once again leaving the defenders with no artillery inside the

perimeter. This second battle raged from 19 to 22 April in much the same form. The

NVA battered the town with artillery, tanks, and infantry assaults while the ARVN used

their light weapons and heavy CAS to repel the attackers.

After another weeklong pause, the Communists made their final attempt to destroy

the garrison of An Loc on May 11. The 5th and 7th NVA divisions threw seven regiments

of infantry against the northeastern and western flanks of an ARVN perimeter that had

95 Ibid., Willbanks, 88. 96 Ibid., Truong, 123; ibid., Nhut, 123. 97 Ibid., MACV, Command History, Vol. II., J-13. 98 Ibid., Nhut, 126.


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shrunk to 1 km by 1.5 km. Once again they relied on artillery to break ARVN resistance;

in the first four hours they fired 7,500 rounds into the ARVN positions and another 10,000

rounds in the twelve hours after sunrise.99 The NVA sought to diminish the effects of U.S.

air power by deploying SA-7 infrared-guided, manportable missiles in large numbers.

These systems were effective against slow, prop-driven FACs, helicopters, and fixed-wing

gunships and their introduction forced the U.S. to withdraw many of these aircraft from

the immediate battle area.100

The last NVA assault collided with the heaviest and best orchestrated aerial fires of

the campaign. Acting on indicators of an impending attack, Hollingsworth had interceded

with Abrams to secure the maximum available air support on May 11. With Abrams’

consent, Hollingsworth was able to vector 300 tacair sorties and 30 B-52 Arc Light

missions into An Loc on May 11th alone; over the next four days, he pushed an average of

260 tacair sorties into An Loc to hammer NVA units and assembly areas. Desperate to

maximize the effects of these sorties, U.S. advisors cleared the use of B-52 Arc Light

strikes within 600 meters of the perimeter.101 Confronted with these withering fires, and

bedeviled by problems with tank/infantry coordination, the last big NVA push ground to a

halt.

While the NVA continued to shell the town with 2,500 rounds per day from May

13-16, the greatest danger had passed. Communist losses and overwhelming aerial

firepower enabled the ARVN to hold An Loc. By 15 June, the Airborne were strong

enough to push back onto the high ground to the south of the town and lift the siege.102

99 Ibid., Willbanks, The Battle of An Loc,117. 100 Ibid., HQ PACAF, Battle for An Loc, 57-59; ibid., Truong, 129. 101 Ibid., MACV, Command History, Vol. II., J-23-25. 102Ibid., MACV, Command History, Vol II., J-29.


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By this time, An Loc had been reduced to a charnel house. The NVA lost three

divisions with their estimated losses coming to 10,000 killed and 15,000 wounded. The

ARVN defenders had suffered 2,300 dead and 3,100 wounded. The town had been almost

entirely destroyed by 78,000 rounds of Communist artillery, more than 700 B-52 Arc

Light strikes, and countless tacair attacks. 103

Even more than in MR I and MR II, the role of air power in defeating the

Communist offensive appears to have been the decisive element. The circumstances of

the siege made An Loc a natural experiment in the influence of air power in support of

ground troops. In contrast to the battles of Kontum and Quang Tri, the defenders of An

Loc never enjoyed the support of ARVN artillery, naval gunfire, or tank support. Instead,

they were entirely reliant on small arms, M-72 LAWs, and U.S. and Vietnamese air

power.104 For the duration of the siege, they also depended almost entirely on aerial

resupply by parachute delivery.105

ARVN commanders were unequivocal in their statements about the importance of

CAS and BAI in the outcome at An Loc. In his postwar study of the battle, LTG Truong

explained the outcome in these terms:

“An Loc had held against overwhelming odds. To a certain extent this feat could be attributed to the sheer physical endurance of ARVN defenders…. But the enemy’s back had been broken and An Loc saved only because of timely B-52 strikes.”106

103 Ibid., Willbanks, The Battle of An Loc, 146-147; ibid., HQPACF, CHECO Division, Battle for An Loc, 63-65. 104 Ibid., HQPACF, CHECO Division, Battle for An Loc, 55. 105 ibid., HQPACF, CHECO Division, Battle for An Loc, 26-36. 106 Ibid., Truong, 131. Lam Quang Thi, Truong’s wartime deputy, came to similar conclusions in his history of the battle of An Loc: “What then were the causes of success of the defense of An Loc? First, it was the air support available that made the biggest difference between An Loc and Dien Bien Phu. Day after day, B-52 sorties hit NVA assembly areas, logistical installations, even the first echelon assault units.” (Lam Quang Thi, Hell in An Loc, 209).


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Captured enemy documents revealed similar opinions on the Communist side. A

handwritten letter seized on April 18 from a political commissar of the 9th VC Division to

COSVN Headquarters explained the Communist failure in terms of the their inability to

coordinate tanks and infantry and “the effects of tactical air and B-52 strikes [that] were

unbelievably devastating.”107

Still, the tactical application of such volumes of air power would not have been

possible without effective coordination mechanisms. U.S. ground advisors, working with

U.S. and Vietnamese FACs, were able to focus these fires onto the enemy while

minimizing the collateral damage to ground forces. During the course of the battle, U.S.

FACs developed increasingly effective procedures for controlling the mass and variety of

platforms in the battle area.108 While less visible than the hardware or munitions

employed, the organizational and procedural software of this system helps explain the

success of air power at An Loc and the failure of CAS/BAI missions in the opening phases

of the defense of Quang Tri.

U.S. air power could not have been effective without the resistance of ARVN

forces and U.S. advisors. On the third day at Loc Ninh, the collapse of ARVN resistance

had vitiated the U.S. advisors’ plans to hold the position with CAS and BAI. At An Loc,

by contrast, the encircled ARVN forces fought tenaciously. As General Abrams aptly

summarized:

“I doubt the fabric of this thing could have been held together without U.S. air. But the thing that had to happen before that is the Vietnamese, some numbers of them, had to stand and fight. If they didn't do that, ten times the air wouldn’t have stopped them”109

107 Ibid, MACV, Command History, Vol. II., J-15. 108 For a detailed discussion of the FAC system at An Loc, see HQPACF, CHECO Division, Battle for An Loc,19. 109 Ibid., Sorley (ed.), Vietnam Chronicles, 826.


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The Battle in the Central Highlands: MR II and the Siege of Kontum

With the battles in MR I and MR III underway, the NVA prepared to launch its

third major attack, this time from Cambodia into the thinly populated Central Highlands.

If the NVA could destabilize the coastal areas of MR II and seize Kontum and Pleiku in

the highlands, they would be able to split the Republic of Vietnam in two. The

Communists invested 20,000 troops of three NVA divisions and separate regiments as

well as heavy artillery and an estimated 400 tanks in this third campaign.110

The NVA’s plan was to proceed in three steps. First, they would cut the flow of

supplies from the coast to the ARVN forward positions in the highlands at Tac Canh,

Kontum, and Pleiku. Second, they would seize Rocket Ridge, the strip of high ground that

dominated the routes leading both to Tac Canh and Kontum. With the high ground in

their possession, the NVA would isolate and destroy the major ARVN garrisons in series,

opening the gate to a triumphant march to the sea.

The ARVN II Corps that stood in their way was considered the weakest of the four

corps in the South Vietnamese army. The commanders, from the Corps Commander

General Dzu down to the regimental commanders, were regarded as ineffectual and U.S.

advisors were pessimistic about their ability to withstand a major attack.111 On 28

December 1971, Brigadier General George Wear, the senior military advisor in II Corps,

described the ARVN situation to General Abrams in these terms:

I wish I could be a lot more optimistic than I really am about the ARVN in II Corps. And I think this time last year I was. They can just about handle the local forces within the boundary. Our experience has been…that when the NVA well-trained

110 Capt. Peter Liebchen, Kontum: Battle for the Central Highlands (30 March- 10 June 1972)(HQ PACAF, Directorate of Operations Analysis CHECO/CORONA Harvest Division, 27 October 1972), 3; ibid., Willbanks, Abandoning Vietnam, 139. 111 Ibid., Andrade, 207-208.


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units come across the border, the ARVN just hasn’t stood up against them…. The two divisions [22nd and 23rd ARVN] I don’t think they’ve really improved in the 17 months I’ve watched them. Their strength runs about the same, 71 to 76 percent…. The leadership problem you know…. I have noticed that when a unit really got into it, and didn’t have a choice, they fought pretty well.”112

Still, Wear’s superior, John Paul Vann, hoped that even moderate ARVN resistance would

allow him to focus B-52 strikes on the attacking formations and break the NVA bid to

seize the highlands.113

Vann was able to impose his thinking on the malleable ARVN II Corps

Commander General Dzu. Over the objections of his own military advisor, BG Wear,

Vann pushed the 22nd ARVN Division forward to meet the anticipated NVA thrust near

Tac Canh.114 The 23rd Division would be spread across the coastal strongholds of MR II.

Vann’s intent was to meet the NVA invasion forward of Kontum and defeat it there with

U.S. air power.115

Vann sought to disrupt the NVA buildup in the highlands using B-52 Arc Light

strikes. The limiting factor in these spoiling attacks was direct observation. Many ARVN

commanders were reluctant to patrol aggressively and pin down the locations of the major

enemy formations.116 Still, in the first three months of the year, Vann employed the B-52s

in a wide-ranging, BAI campaign against the NVA in the western sanctuaries of MR II.

The volume of air power was remarkable. In January and February the bombs of more

than 100 B-52 bombers fell on the Central Highlands with more than eighty of those

coming in February alone.117 As prisoner and defector reports would later reveal, these

112 BG George Wear as quoted in ibid., Sorley (ed.), Vietnam Chronicles, 730-731. 113 Ibid., McKenna, Kontum: The Battle to Save South Vietnam, 47; ibid., Andrade, 214-215, 217. 114 Ibid., McKenna, 30. 115 Ibid., McKenna, 52, 82-84. 116 Ibid., MACV Command History January 1972-March 1973, Vol. I, K-1; ibid., Andrade, 213; ibid., McKenna, 29, 87. 117 Ibid., McKenna, 53, 98.


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thinly observed strikes had a devastating impact on the NVA units. One POW from the

320th NVA Division captured in mid-May testified that his regiment of 2,500 men had

suffered 1,200 casualties before it launched its first attack on Kontum. Equally important,

these attacks appear to have delayed the start of the NVA campaign in the Central

Highlands. This delay meant that the third NVA campaign would unroll after the

campaigns in the north and south had largely culminated.118 This would enable the U.S.

military to focus the full weight of its air power on Kontum when the test came.

Despite Vann’s best efforts, the preparatory phases of the NVA offensive were

broadly successful. The NVA seized An Khe pass in early April and cut the major line of

supply from the coast to the highlands; it would take ARVN and South Korean forces a

full month to clear this roadblock and restore steady supplies. At the same time, the NVA

diversionary attacks in coastal Binh Dinh province allowed VC cadre to seize control in a

number of villages and towns.119 Most important, in early April the NVA began to isolate

and attack the series of ARVN firebases strung out from north to south along Rocket

Ridge. While those firebases held out for a time, by the last week of April these posts

began to fall or withdraw under heavy NVA pressure.120 Once ensconced on those

dominating heights, the NVA began to assemble the troops and artillery necessary to

launch its deliberate attacks on Tan Canh and Kontum.121

On 23 April, the first major blow fell on two regiments of the 22nd ARVN Division

at Tac Canh and Dak To. Neither regiment was prepared for the scale and ferocity of the

assaults; two NVA Divisions and four separate regiments attacked the two ARVN

118 Ibid., McKenna, 53, 193-194. 119 Ibid., McKenna, 74, 132; Andrade, 220-227. 120 Ibid., MACV Command History, Vol I., K-5. 121 Ibid., Truong, 85; ibid., Andrade, 232.


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regiments in their positions. In addition to their use of heavy artillery and tanks, the NVA

employed AT-3 Sagger antitank missiles for the first time. These missiles quickly

knocked out the ARVN tanks and command posts and contributed to the complete

disintegration of the 42nd and 47th Regiments.122 By 24 April, both positions had fallen to

the NVA, the 22nd ARVN Division had been shattered, and Vann’s plan of forward

defense lay in tatters. In the rapid collapse, the ARVN lost twenty-three 105mm

howitzers, seven 155mm howitzers, ten M-41 tanks, and 14,000 rounds of artillery

ammunition. Much of this materiel fell into NVA hands intact; many of these weapons

would soon be turned on the defenders of Kontum.123

Vann immediately set to work on a new line of defense. Colonel Ba, the

commander at Kontum, convinced Vann to bring the three regiments of the 23rd Division

to defend the city, bringing the total garrison to around 5,000 troops. Vann also set his

new deputy, Brigadier General Hill, to work on the problem of controlling artillery fires

and air support. Anticipating the high volume of U.S. and VNAF air strikes in the coming

battle, he announced that there would be a single air boss in an OH-58 helicopter acting as

a “traffic cop” in the skies over Kontum.124 More important, Hill brought in a new Air

Liaison Officer, USAF Colonel Swenholt, to reorganize the air effort at II Corps HQ in

Pleiku. In contrast to the situation in MR I, the II Corps Direct Air Support Center

(DASC) had not completed its transition to South Vietnamese control by the time of the

offensive and this made a restoration of U.S. control over air operations far simpler.125 As

122 Ibid., McKenna, 100-103, 107. 123 Ibid., Andrade, 250; ibid., McKenna, 120. 124 Ibid., McKenna, 126-127. 125 Ibid., Liebchen, 33.


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the Senior Fighter Duty Officer at II DASC later explained, the procedures used to control

tacair and B-52s varied considerably:

TACAIR is used with FACs. FACs go out and look for targets, or the ground commander will direct them to a target or give them an area to check out. He calls back here with the coordinates to be cleared, and also requests air at the same time. We clear the target here by going through ARVN channels. After that’s done, we have our incoming air that’s been fragged to us; we parcel it out to the FAC depending on what priority target he’s got…. [As for the B-52s] Frankly, that’s no longer an Air Force weapon. We fly the airplanes, but the (U.S.) Army puts in the target request; they handle the clearing, etc.126

As the volumes of air support increased and the battle for Kontum began in earnest, this

procedural backbone for cooperation between USAF controllers and U.S. ground advisors

proved the key to the successful application of CAS and BAI.

The NVA paused for