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The Combined Action Program:


Captain Keith F. Kopets, USMC

"Of all our innovations in Vietnam none was as successful, as lasting in effect, or as useful for the future as the Combined Action Program [CAP]," wrote U.S. Marine Corps (USMC) Lieutenant General (LTG) Lewis Walt in his memoirs.1 British counterinsurgency expert Sir Robert Thompson said CAP was "the best idea I have seen in Vietnam."2

The program, undertaken by the USMC during the Vietnam war, was an innovative and unique approach to pacification. In theory, the program was simple; a Marine rifle squad would join forces with a South Vietnamese militia platoon to provide security for local villages. CAP's modus operandi made it unique. While assigned to combined units, Marines would actually live in a militia unit's village.

CAP was a response to the conditions in Vietnam. As the senior command in the I Corps Tactical Zone, the Marines were responsible for securing more than 10,000 square miles of land that included the five northernmost provinces of South Vietnam. More than 2-1/2 million people lived in the I Corps area. Using the militia for local security made sense; there were not enough Marines to go around.

The Marines and the U.S. Military Assistance Command, Vietnam, disagreed on war strategies. U.S. Army leaders wanted to search and destroy the communists in the rural and less-populated areas of South Vietnam; the Marines wanted to clear and hold the populated areas. CAP was a manifestation of the strategy the Marines felt best suited the conditions in Vietnam.

With U.S. Marines living and fighting side-by-side with the Vietnamese people, CAP seemed to rep-resent an effective, long-term, around-the-clock commitment to combating the Vietnamese communists at the grassroots level. CAP worked well in some locations; elsewhere, its results were transitory at best—with villagers becoming overreliant on the Marines for security.

CAP's Origins

CAP came naturally for the Marine Corps because counterguerrilla warfare was already part of the USMC heritage. From 1915 to 1934, the Corps had a wealth of experience in foreign interventions fighting guerrillas in Nicaragua, Haiti, and Santo Domingo. For example, the Marines organized and trained the Gendarmerie d'Haiti and the Nacional Dominicana in Haiti and Santo Domingo from 1915 to 1934. In Nicaragua (1926-1933), the Marines organized, trained, and commanded the Guardia Nacional de Nicaragua. These organizations were nonpartisan, native constabularies the Marines commanded until host-nation forces could competently assume command.3

Senior USMC generals in Vietnam had studied as lieutenants such interventions—called "small wars." But more than that, As Commanding General (CG), Fleet Marine Forces Pacific, LTG Victor H. Krulak was responsible for training and readiness of all the Marines in Vietnam. As CG, III Marine Amphibious Force, Walt directed the operations of all the Marines in I Corps.

Krulak and Walt began their careers during the 1930s and 1940s under the tutelage of such Caribbean Campaign veterans as LTG Lewis B. "Chesty" Puller, Sr., and Major General (MG) Merritt "Red Mike" Edson. In Vietnam, Krulak and Walt applied the lessons they had learned about guerrilla fighting.4

When the Marines arrived in South Vietnam in 1965, they occupied and defended three enclaves in the I Corps area: Phu Bai, Da Nang, and Chu Lai. CAP grew out of an experiment that Lieutenant Colonel (LTC) William W. Taylor's 3d Battalion, 4th Marine Regiment, conducted near Phu Bai.5

Taylor's infantry battalion defended 10 square miles and a critical airfield at Phu Bai. He knew his three rifle companies were not enough to defend that amount of territory. The local population lived in six villages, each nominally defended by a militia platoon. Taylor and his officers brainstormed ideas of how to improve the battalion's defensive posture. They looked to a previously unused resource—the militia platoons.

Taylor's executive officer, Major Cullen C. Zimmerman drafted a plan to incorporate the militia platoons into the battalion's defense. He proposed integrating the militia platoons into the battalion's rifle squads to form a combined unit.

Taylor liked Zimmerman's plan and forwarded it to Colonel Edwin B. Wheeler, the regimental commander. Wheeler also liked the plan and pushed it all the way up the chain of command to Walt and Krulak. Both generals liked the idea, and Walt sold the idea to South Vietnamese General Nguyen Van Chuan. Chuan, who was responsible for the Vietnamese military forces in Phu Bai, agreed to give Walt operational control over the militia platoons operating in Taylor's sector.

Taylor integrated four rifle squads from his battalion with the six local militia platoons in early August 1965. First Lieutenant Paul R. Ek commanded the combined unit, known as a Joint Action Company. Ek, who had already served as an adviser to a U.S. Army Special Forces unit in Vietnam and spoke the language, was well versed in coun-terguerrilla warfare. The Marines in Ek's combined company were volunteers from the 3d Battalion, 4th Marines, and each had been carefully screened by Zimmerman.6

The Phu Bai experiment yielded promising results. The Marines instilled an aggressive, offensive spirit in their counterparts and gave the militia something it had never had before—leadership. The Marines also learned from the Vietnamese, gaining knowledge of local terrain and learning Vietnamese customs and courtesies. Winning fights against local enemy guerrillas, Ek's combined unit upset the status quo by driving the communists out of the villages.

Walt seized on the success of Ek's unique company in Phu Bai and approached Vietnamese General Nguyen Chanh Thi, his counterpart, with a proposal to expand the program to include Da Nang and Chu Lai. Walt did not need to put the hard sell on Thi; he was already impressed by the Phu Bai experiment.

CAP Expansion

Because of Walt and Thi's enthusiasm, CAP stopped being an experiment and started becoming an integral part of the Marine Corps' war in the I Corps area. The platoon became the program's basic tactical unit. A 35-man Vietnamese militia platoon, and a 13-Marine rifle squad, with one attached U.S. Navy hospital corpsman, formed the combined-action platoon. This unit lived in and operated out of the local village of the militia platoon.7

U.S. and Vietnamese chains of command remained separate. The Marines were only supposed to serve as advisers to their counterparts, and they did—in garrison. In the bush, on patrol, the senior Marine present became the de facto commander of the combined unit.

From the original 6 platoons at the end of 1965, the number of combined units grew to 38 platoons by July 1966. By January 1967, 57 combined platoons operated throughout the I Corps area—31 platoons in the Da Nang enclave and 13 each in the Phu Bai and Chu Lai enclaves. The number of combined platoons peaked at 114 in 1970, and the units had spread throughout the five provinces in the I Corps area.8

Increasing the number of combined platoons caused problems for Walt. For one, he needed more Marines. He was robbing Peter to pay Paul by taking men from his two infantry divisions and assigning them to combined units. Headquarters was not sending Walt more men to make up the difference. A limit on troop strength in Vietnam had already been set so as to meet commitments elsewhere.9

To get into CAP, Marines needed to be volunteers, have already served 2 months in country yet still have at least 6 months left on their tours, have a recommendation from their commanding officers, and once selected, had to attend a 2-week school, which offered instruction in Vietnamese language and culture and small-unit tactics.10

Marine infantry commanders were hesitant to release their best noncommissioned officers for duty with combined units; they knew they would not receive replacements. And because infantry commanders did not always give up their best men for CAP, the quality of combined platoons ranged from outstanding to abysmal, based on the amount of the Marines' experience, proficiency, and maturity.11

Walt acted on these problems. In February 1967, he appointed LTC William R. Corson as his Director for Combined Action.12 Corson was the right man for the job. He had fought with the Marines in the Pacific and Korea and had completed a tour in Vietnam as a tank battalion commander. Corson spoke four Chinese dialects, held a doctor's degree in economics, and had experience in unconventional warfare in Vietnam. He had also served with the Central Intelligence Agency in Southeast Asia from 1958 to 1959, organizing guerrilla operations against the Viet Minh.13

Corson believed CAP required its own chain of command and objected to the existing command arrangement that gave local infantry commanders control of the combined units in their areas of responsibility. He did not believe the average infantry battalion commander in Vietnam knew what it took to succeed in the business of pacification. According to writer Robert A. Klyman, Corson "was there to kill enemy. . . . His mission was two up, one back, hot chow. Battalion commanders were not in Vietnam to win the hearts and minds of the people. . . . They were playing the game of . . . search and destroy. They didn't understand the nature of the war they were involved in."14

Corson wanted mobility in each of his platoons. "The [combined-action platoon] will [not] function as the garrison of a so-called `French Fort,'" he wrote.15 The platoon must "conduct an active, aggressive defense [of its assigned village] to prevent [communist] incursions and attacks directed at the hamlet residents and officials."16

In July 1967, Corson drafted a set of standing operating procedures charging each of his platoons with six different missions:

1. Destroy the communist infrastructure within the platoon's area of responsibility.

2. Protect public security; help maintain law and order.

3. Organize local intelligence nets.

4. Participate in civic action and conduct propaganda against the communists.

5. Motivate and instill pride, patriotism, and aggressiveness in the militia.

6. Conduct training for all members of the combined-action platoon in general military subjects, leadership, and language, and increase the proficiency of the militia platoon so it could function effectively without the Marines.17

CAP Problems

The relationship between the Marines and the Vietnamese militia was the key to CAP's success. Theoretically, each combined platoon derived its strength from fusing the two primary elements—the militia soldier and the U.S. Marine—into a single operational entity. Because the political climate did not allow Americans to command Vietnamese forces, the Marines had no formal authority over the militia.18 Walt and Corson hoped decentralized control and close coordination and cooperation could resolve any problems caused by this tenuous command relationship.

There were serious problems with the Vietnamese militia. They were woefully incapable of defending the villages by themselves. One official account reads: "In general, the equipment and training of the [militia] platoons and their unimaginative use in static defensive positions made them a slender reed in the fight against the Viet Cong."19 At US$19 a month, the militia soldier earned less than half that of his regular Vietnamese Army counterpart.20 Corruption and graft were accepted practices, and village chiefs controlled the militia and padded the muster rolls of their platoons to extort the salaries of "ghost" soldiers.21

The Marines also had problems. The combined platoons modus operandi—living and fighting alongside the Vietnamese population—required the Marines to adapt to a culture radically different from their own. Most of the Marines were junior enlisted men in their late teens or early twenties. Expecting men of these ages to quickly adapt to such foreign surroundings while also serving in a combat zone was a tall order.22

The majority of the Marines who served with combined units from 1965 to 1967 came directly from the infantry. This was not the case, though, as the war continued. From 1968 to 1970, many Marines joined combined platoons from rear-echelon support units and lacked basic infantry skills. In 1969, a senior CAP commander in Quang Tri province wrote of these shortcomings: "Sound tactics are not God-given; they are not inherited or acquired automatically. Not one young corporal or sergeant in a hundred has adequate competence in this field. Their understanding of the proper use of terrain, the control of the point element, all-around security, fire and maneuver, fire superiority, fire control and discipline (to say nothing of the psychological and morale forces involved) leave much to be desired. In six months, I have yet to see any [combined-unit] leader working to improve his own knowledge or understanding of tactics.23

Vietnam Strategies

Notwithstanding its problems in execution, CAP seemed a viable strategy for providing local security in South Vietnam. Some analysts speculate there would have been a much different outcome to the war had the United States applied the Marines' strategy on a larger scale.24 One of the main reasons why the program never expanded beyond the borders of the I Corps area was because General William C. Westmoreland, the senior U.S. Army commander in Vietnam, subscribed to a different strategy.

Westmoreland believed the regular North Vietnamese Army and main-force communist battalions posed the greatest threat to the government of South Vietnam, not the guerrillas operating in the south. He pursued a strategy through which he could exploit the U.S. advantage in mobility and firepower to engage the most threatening communist units. After the United States won the "big unit" war against conventional enemy formations, the South Vietnamese Army could focus on the "other war" against the entrenched communist political infrastructure. This formed the philosophical underpinning for the search and destroy attrition strategy.25

Krulak believed pacification and protection of the South Vietnamese population—a clear-and-hold approach—was more appropriate than the search-and-destroy attrition strategy. "If the people were for you," he wrote, "you would triumph in the end. If they were against you, the war would bleed you dry, and you would be defeated."26

Westmoreland believed population security was a Vietnamese task. However, he did write in his memoirs that CAP was one of the more "ingenious innovations developed in South Vietnam."27 Westmoreland also offered this explanation: "Although I disseminated information on the [combined action] platoons and their success to other commands, which were free to adopt the idea as local conditions might dictate, I simply had not enough numbers to put a squad of Americans in every village and hamlet; that would have been fragmenting resources and exposing them to defeat in detail."28

A Viable Approach

By 1970, "a total of 93 [combined platoons] had been moved to new locations from villages and hamlets deemed able to protect themselves. Of these former CAP hamlets, the official Marine Corps history of the Vietnam war claims that "none ever returned to Viet Cong control."29 These figures are spurious at best, as are most other attempts to quantify the war in Vietnam.

Edward Palm, an English professor and former CAP Marine, is not as sanguine as the official Marine Corps history: "I would like to believe, with some, that combined action was the best thing we did [in Vietnam]. . . . In my experience, combined action was merely one more untenable article of faith. The truth, I suspect, is that where it seemed to work, combined action wasn't really needed, and where it was, combined action could never work.

"The objective was certainly sound. There was a demonstrable need for an effective grassroots program targeted toward the [communist] infrastructure, for the most part left intact by large-scale search and destroy operations. But combined action came too little, too late. The [communist] infrastructure was too deeply entrenched, literally as well as figuratively, in some places. They had had more than 20 years to win hearts and minds before we blundered onto the scene. We were naïve to think 13 Marines and a Navy corpsman could make much difference in such a setting. The cultural gulf was just unbridgeable out in the countryside."30

Even at its zenith of 2,220 men, CAP represented only 2.8 percent of the 79,000 Marines in Vietnam. Yet during its 5-year lifespan, combined units secured more than 800 hamlets in the I Corps area, protecting more than 500,000 Vietnamese civilians.31

CAP was not the magic ingredient that would have won the war in Vietnam, but it was a viable approach to counterguerrilla warfare, worthy of further study. What better way was there for learning about the enemy in such a war than fighting with the militia and living with the local populace? No wonder CAP Marines became some of the best sources of intelligence in the Vietnam war as well as some of the best small-unit leaders. They had to be, operating as they did, in order to survive. Air strikes, free-fire zones, and massive demonstrations of firepower were commonplace throughout South Vietnam, but such were rare occurrences near villages with combined-action platoons.

The Battle for Hue City and the siege at Khe Sanh dominate the literature about the Marines in Vietnam. CAP, however, was the Corps' greatest innovation during the war. MR


1.Lewis W. Walt, Strange War, Strange Strategy: A General's Report on the War in Vietnam (New York: Funk and Wagnalls, 1970), 105.

2.Quoted in Andrew F. Krepinevich, Jr., The Army and Vietnam (Baltimore, MD: Johns Hopkins, 1986), 174.

3.On the Marines in Nicaragua, see Neill Macaulay, The Sandino Affair (Chicago: Quadrangle Books, 1967). On the Marines in Hispaniola, see Hans Schmidt, Maverick Marine: General Smedley D. Butler and the Contradictions of American Military History (Lexington: University Press of Kentucky, 1987), 74-95. See also Graham A. Cosmas, "Cacos and Caudillos: Marines and Counterinsurgency in Hispaniola, 1915-1924," in New Interpretations in Naval History: Selected Papers from the Ninth Naval History Symposium, William R. Roberts and Jack Sweetman, eds. (Annapolis, MD: Naval Institute Press, 1991), 293-308. For a comparison of CAP with the constabularies the Marines organized in Latin America, see Lawrence A. Yates, "A Feather in their CAP? The Marines' Combined Action Program in Vietnam," in ibid., 320-1.

4.Victor H. Krulak, First to Fight: An Inside View of the U.S. Marine Corps (Annapolis, MD: Naval Institute Press, 1984), 190-1; Walt, 29; Jon T. Hoffman, Once a Legend: "Red Mike" Edson of the Marine Raiders (Novato, CA: Presidio Press, 1994), 98, 122-3. Puller and Edson, who served with distinction as officers in the Guardia Nacional de Nicaragua, also served successively as small-wars instructors during the 1930s. Walt and Krulak were their students and, as captains, served with Edson and Puller in the Pacific during World War II.

5.Ibid., 38-40.

6.Robert A. Klyman, "The Combined Action Program: An Alternative Not Taken" (Honors thesis, University of Michigan, Ann Arbor, 1986), 4-5; Michael Duane Weltsch, "The Future Role of the Combined Action Program" (Master of Military Art and Science thesis, U.S. Army Command and General Staff College, Fort Leavenworth, 1991), 57-65.

7.III MAF [Marine Amphibious Force] Force Order 3121.4A, sub [subject]: SOP [Standing Operation Procedures] for the Combined Action Program, dtd [dated] 17 July 1967 (hereafter, CAP SOP), in CAF [Combined Action Force] History and SOP Folder, Box 2, Pacification Study Docs [Documents], Marine Corps Historical Center (MCHC), Washington, DC; Jack Shulimson, U.S. Marines in Vietnam 1966: An Expanding War (Washington, DC: History and Museums Division, HQMC, 1982), 239-43; Gary L. Tefler, Lane Rogers, and V. Keith Fleming, Jr., U.S. Marines in Vietnam, 1967: Fighting the North Vietnamese (Washington, DC: History and Museums Division, HQMC, 1984), 186-95; William R. Corson, The Betrayal (New York: W.W. Norton, 1968), 181-3.

8.Shulimson, 239; Tefler, et al., 187; Weltsch, 65.

9.Corson, 178.

10.CAP SOP; Corson, 183-4; Edward F. Palm, "Tiger Papa Three: A Memoir of the Combined Action Program," Marine Corps Gazette (January 1988), 35; CAP School syllabus, 21 August-1 September 1967, and CAP School diploma, dated 25 February 1969, in Michael E. Peterson, "The Combined Action Platoons: The U.S. Marines' Other War in Vietnam" (M.A. thesis, The University of Oregon, Eugene, 1988), 285-91. Peterson is a CAP veteran. Praeger Publishers published this thesis in 1989.

11.Ltr [Letter], CG [Commanding General], III MAF to CG FMFPac [Fleet Marine Force Pacific], sub: Combined Action Group Headquarters, Organization, Equipment, Functions and Concept of Operations, dtd 4 May 1967, MCHC; Ltr, CO [Commanding Officer], CAF to CG, XXIV Corps, sub: CORDS [Civil Operations for Rural Development Support] Survey of CAP Villages, dtd 24 March 1970, MCHC (hereafter, Ltr, CO, CAF). See also Ronald H. Spector, After Tet: The Bloodiest Year in Vietnam (New York: The Free Press, 1993), 195; Shulimson, 240; Klyman, 13. Klyman quotes Colonel G.E. Jerue, a former regimental commander in the 3d Marine Division: "Although the requirement states that they [CAP Marines] should be volunteers, it doesn't demand volunteers. We more or less had to go by the rule of thumb that if the man doesn't object, he is a volunteer for it."

12.Corson, 179-80.

13.Peterson (Praeger), 39-41.

14.Klyman, 22.



17.Ltr, CO, 4th CAG [Combined Action Group] to 4th CAG CACO [Combined Action Company] Commanders, sub: Tactical Operations, Policies and Guidance, dtd 14 January 1969, MCHC (hereafter, Ltr, CO, 4th CAG); Corson, 174-98; CAP SOP.

18.CAP SOP; Corson, 183-4; Palm, 35; CAP School syllabus and CAP School diploma in Peterson, 285-91.

19.Richard A. Hunt, Pacification: The American Struggle for Vietnam's Hearts and Minds (Boulder, CO: Westview Press, 1995), 34-35.

20.Russel H. Stolfi, U.S. Marine Corps Civic Action Efforts in Vietnam, March 1965-March 1966 (Washington, DC: Historical Branch, G3 Division, HQMC, 1968), 39.

21. Krulak, 187-189; David H. Wagner, "A Handful of Marines," Marine Corps Gazette (March 1968), 45; Hunt, 91.

22.Hunt, 39.

23.See Ltr, CO, CAF.

24.Ltr, CO 4th CAG.

25.Krepinevich, 172-7. Krepinevich argues in favor of expanding combined action throughout Vietnam. Unfortunately, his approach does not take full account of the recruiting problem that would accompany such an expansion. Spector highlights a few of the problems: "The ideal CAP Marine was a cool and efficient infantry fighter, not only expert in the skills of combat but able to impart these skills to an untrained, uneducated farmer who spoke little or no English. At the same time, he was a patient, subtle, and resourceful community organizer, able to overcome cultural barriers and prejudice to win the hearts and minds of the villagers. Such men, if they existed at all, were in short supply" (195).

26.George C. Herring, America's Longest War: The United States and Vietnam, 1950-1975, 2d ed. (New York: McGraw-Hill, 1986), 150; Allan R. Millett and Peter Maslowski, For the Common Defense: A Military History of the United States of America, rev ed. (New York: The Free Press, 1993), 580; Phillip B. Davidson, Vietnam at War: The History, 1946-1975 (New York, Oxford University Press, 1991), 352-4; William C. Westmoreland, A Soldier Reports (New York: Dell, 1980), 215-6.

27.Krulak, 194; see also Neil Sheehan, A Bright and Shining Lie: John Paul Vann and America in Vietnam (New York: Random House, 1988), 629-33.

28.Westmoreland, 216.


30.Graham A. Cosmas and Terrence P. Murray, U.S. Marines in Vietnam: Vietnamization and Redeployment, 1970-1971 (Washington, DC: History and Museums Division, HQMC, 1986), 149. For a description of a successful combined platoon, see Francis J. West, The Village (Madison: University of Wisconsin Press, 1985). West tells the story of the Binh Nghia combined platoon, which operated from May 1966 to October 1967 near Chu Lai.

31.Palm, 76.

32.III MAF Combined Action Force Deactivation Ceremony Program, dated 21 September 1970, in Peterson, 334-5.

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