Joint warfare in South Vietnam 1964-1968
- 1 Centers of gravity
- 2 Military strategy
- 3 The "other war"
- 4 Fighting continues; 1964 winter offensive
- 5 1964-1965 winter offensive
- 6 U.S. decision to escalate
- 7 Decision and worry
- 8 1965-1966 winter-spring offensive
- 9 Winter-Spring 1967
- 10 1967-1968 North Vietnamese offensive
- 11 Summer 1968
- 12 Winter 1968
- 13 References
In the Vietnam War, after the Gulf of Tonkin incident in 1964 and the continuing political instability in the South, the United States made a policy commitment to begin joint warfare in South Vietnam, involving the commitment of large-scale combat forces from the United States and allied countries. It was no longer assumed the Republic of Vietnam could create a desirable situation without major external assistance. This phase of the war lasted until the election of Richard M. Nixon, and the change of U.S. policy to Vietnamization, or giving the main combat role back to the South Vietnamese military.
The North Vietnamese term for the large-scale introduction of U.S. ground forces, in 1965, is the Local War. According to Gen. Tran Van Tra, the [North Vietnamese] " Party concluded, the "United States was forced to introduce its own troops because it was losing the war. It had lost the political game in Vietnam....the situation allows us to shift our revolution to a new stage, that of decisive victory." The Party issued a resolution to this effect, which was transmitted, in October 1967, to the Central Office for South Vietnam and to key officials of the major commands in the South. They were directed to begin detailed planning for what was to become the Tet Offensive.  Note that there was a delay of approximately two years between the Politburo decision and the directive to begin planning, so it can be asked if the Politburo did actually make the broad strategic decision in 1965, or some time later, as they grew more aware of the effect of U.S. operations.Robert McNamara suggests that the overthrow of Duong Van Minh by Nguyen Khanh, in January 1964, reflected different U.S. and Vietnamese priorities.
"And since we still did not recognize the North Vietnamese and Vietcong and North Vietnamese as nationalist in nature, we never realized that encouraging public identification between Khanh and America may have only reinforced in the minds of many Vietnamese that his government drew its support not from the people, but from the United States."Minh's government had been exploring neutralist solutions, which did not fit within the broad anti-communist containment policy of the United States.
Centers of gravity
Unfortunately, the Government of the Republic of Vietnam, at a broad level, was principally motivated not to lose, rather than achieve some goal. In contrast, the U.S. and North Vietnam did have strategic goals, with very different, and often inaccurate, definitions of the center of gravity of the opposition.
Lyndon Johnson and Robert McNamara, in selecting a strategy in 1965, had assumed the enemy forces were assumed that much as the defeat of the Axis military had won the Second World War, the Communist military was the center of gravity of the opposition, rather than the political opposition or the security of the populace.
North Vietnamese theorists, however, knew they could not beat U.S. forces in the field, and formed models, such as General Offensive-General Uprising, that treated the populace, especially the urban populace, as the center of gravity.
William Westmoreland, and to a lesser extent Maxwell Taylor, rejected, if they seriously considered, the protracted war doctrine stated by Mao and restated  by the DRV leadership, mirror-imaging that they would be reasonable by American standards, and see that they could not prevail against steady escalation. They proposed to defeat an enemy, through attrition of his forces, who guided by the Maoist doctrine of Protracted War, which itself assumed it would attrit the counterinsurgents. An alternative view, considering overall security as the center of gravity, was shared by the Marine leadership and some other U.S. government centers of opinion, including Central Intelligence Agency, Agency for International Development, and United States Army Special Forces.
Roughly until mid-1965, the SVN-US strategy still focused around pacification in South Vietnam, but it was increasingly irrelevant in the face of larger and larger VC conventional attacks. Military Assistance Command, Vietnam began to refer to the "two wars", one against conventional forces, and the other of pacification. The former was the priority for U.S. forces, as of 1965, assuming the South Vietnamese had to take the lead in pacification. Arguably, however, there were three wars:
- Ground combat in South Vietnam, including air operations in direct support
- Air operations against North Vietnam
- Pacification in South Vietnam
There were, however, changes in the overall situation from early 1964 to the winter of 1965-1966, from 1966 to late 1967, and from late 1968 until the U.S. policy changes with the Nixon Administration.
North Vietnamese views
While the discussion following splits into military and political/civil strategies, that is a Western perspective. Relevant Communist theory takes a more grand strategic view than did the U.S. and South Vietnam, in their concept of dau trinh, or "struggle", where the goal is always political; there are both military and organizational measures that support the political goal.
One major thrust was the General Offensive-General Uprising, but this was increasingly overcome by a concentration on defeating political and popular opposition in the United States. Once the United States was no longer likely to intervene, the North Vietnamese changed their idea of center of gravity to destroying the Army of the Republic of Viet Nam, and taking and holding land.
Military developments in this period should be considered in several broad phases that do not fit neatly into a single year:
- Gradual intensification, and North Vietnamese exploration of a changed ground environment. Significant events include the Battle of the Ia Drang and the Battle of Bong Son, as well as joint "search and destroy" operations against Communists. During this period, the U.S. concept of the joint war developed.
- A North Vietnamese strategic buildup for what they saw as decisive actions in 1967-1968
- The 1967-1968 campaign, which appears to have had a broader concept, not executed, than the most obvious aspects of the Battle of Khe Sanh and the Tet Offensive.
The U.S. plans
Some fundamental decisions about U.S. strategy, which would last for the next several years, took place in 1965. Essentially, there were three alternatives:
- Bombing, enclave and rural security, principally supported by U.S. Ambassador to South Vietnam, Maxwell Taylor GEN (U.S. Army, retired)
- Attrition of VC bases and secondarily personnel, the focus of GEN William Westmoreland, commanding general, Military Assistance Command, Vietnam. Westmoreland, in a March 26 message, said that it would take six months for air attacks to take effect, and third-country ground troops were needed immediately. Westmoreland stated "search and destroy" as a goal in May
- Emphasis on rural security, from a number of U.S. Marine Corps officer including then-LTG Leonard Cushman, then-MG Victor Krulak, and others
Even with these three approaches, there was still significant doubt, in the U.S. government, that the war could be ended with a military solution that would place South Vietnam in a strongly anticommunist position. In July, two senior U.S. Department of State officials formally recommended withdrawal to President Lyndon B. Johnson; Secretary of Defense Robert McNamara, at the same time, saw the situation as bad but potentially retrievable with major escalation.
Westmoreland's "ultimate aim", was:
"To pacify the Republic of [South] Vietnam by destroying the VC—his forces, organization, terrorists, agents, and propagandists—while at the same time reestablishing the government apparatus, strengthening GVN military forces, rebuilding the administrative machinery, and re-instituting the services of the Government. During this process security must be provided to all of the people on a progressive basis." Source: Directive 525-4 (MACJ3) 17 September 1965: Tactics and Techniques for Employment of US Forces in the Republic of Vietnam 
Westmoreland complained that, "we are not engaging the VC with sufficient frequency or effectiveness to win the war in Vietnam." He said that American troops had shown themselves to be superb soldiers, adept at carrying out attacks against base areas and mounting sustained operations in populated areas. Yet, the operational initiative— decisions to engage and disengage—continued to be with the enemy. 
North Vietnamese strategic buildup
In December 1963, the Politburo apparently decided that it was possible to strike for victory in 1965. Theoretician Truong Chinh stated the conflict as less the classic, protracted war of Maoist doctrine, and the destabilization of doctrine under Khrushchev, than a decision that it was possible to accelerate. "on the one hand we must thoroughly understand the guideline for a protracted struggle, but on the other hand we must seize the opportunities to win victories in a not too long a period of time...There is no contradiction in the concept of a protracted war and the concept of taking opportunities to gain victories in a short time." Protracted war theory, however, does not urge rapid conclusion. Palmer suggests that there might be at least two reasons beyond a simple speedup:
- The Politburo wanted to prevent Southern Communist dominance in an eventual victory, so by introducing Northern troops, they could take away that opportunity
- They thought they would be defeated if they did not take decisive action
They may also have believed the long-trumpeted U.S. maxim of never getting involved in a land war in Asia, and that the U.S. was too concerned with Chinese intervention to use airpower outside South Vietnam.
Once the elections were over, North Vietnam developed a new plan to move from the Ho Chi Minh trail in Cambodia, in central Vietnam (i.e., ARVN II Corps tactical zone), with a goal of driving through to the seacoast over Highway 19, splitting South Vietnam in half. For this large operation, the PAVN created its first division headquarters, under then-brigadier general Chu Huy Man. This goal at first seemed straightforward, but was reevaluated when major U.S. ground units entered the area, first the United States Marine Corps at Danang, and then the 1st Cavalry Division (Airmobile), the "First Cav". In particular, the PAVN were not sure of the best tactics to use against the air assault capability of the 1st Cav, so BG Man revised a plan to bring to try to fight the helicopter-mobile forces on terms favorable to the North Vietnamese. They fully expected to incur heavy casualties, but it would be worth it if they could learn to counter the new U.S. techniques, inflict significant casualties on the U.S. Army, and, if very lucky, still cut II CTZ in half. That planned movement was very similar to the successful PAVN maneuver in 1975.
- PAVN attack on the Plei Me CIDG camp, ambushing the expected heavy rescue force and possibly attracting the 1st Cav,
- Putting simultaneous pressure on Plei Me and Pleiku, so II CTZ would need to call in U.S. reinforcements; this is what became the Battle of the Ia Drang in popular Western terms, but has been called either the U.S. Battle of the Ia Drang or the Pleiku Campaign,
- An ARVN counteroffensive against the PAVN troops retreating into Cambodia, an action fought by the ARVN Airborne Brigade with U.S. air and artillery support.
In the larger Battle of Bong Son approximately a month later, which extended into 1966, 1st Cav drew their own lessons from what they believed the PAVN developed as countertactics to air assault, and used obvious helicopters to cause the PAVN to retreat onto very reasonable paths to break away from the Americans — but different Americans had silently set ambushes, earlier, across those escape routes.
By late 1966, however, North Vietnam began a buildup in the northwest area of the theater, in Laos, the southernmost part of the DRV, the DMZ, and in the northern part of the RVN.
North Vietnamese plans for decisive action
It is known that the North Vietnamese planned something called the Tet Mau Than or Tong Kong Kich/Tong Kong Ngia (TCK/TCN, General Offensive-General Uprising) One of the great remaining questions is if this was a larger plan into which the Battle of Khe Sanh and Tet Offensive were to fit. If there was a larger plan, to what extent were North Vietnamese actions in the period of this article a part of it? Douglas Pike believed the TCK/TCN  was to have three main parts:
- October-November 1967: "concentrated" fighting methods, with raids against small to medium military bases such as Con Thien or Loc Ninh, essentially as large raids: "not a decisive battle but a punitive one"
- January-March 1968: "independent" fighting methods, often small, such as the squads that hit the U.S. Embassy. The operational message was that there were no safe areas.
- Something identified in their message against a large target, a "psychological backbreaker" against a target like Khe Sanh, Hue, Kontum, or Saigon.
Pike used Dien Bien Phu as an analogy for the third phase, although Dien Bien Phu was an isolated, not urban, target. Losing elite troops during the Tet Offensive never let them develop the "second wave" or "third phase" "We don't ever know what the second wave was; we have never been able to find out because probably only a couple of dozen people knew it." The description of the three fighting methods is consistent with the work of Nguyen Chi Thanh, who commanded forces in the south but died, possibly of natural causes, in 1967; Thanh may very well have been among those couple of dozen. Thanh was replaced by Tran Van Tra. Tra's analysis (see above) was that while the concept of the General Offensive-General Uprising was drawn up by the Politburo in 1965, the orders to implement it did not reach the operational headquarters until late October 1967. 
Pike described it as consistent with the armed struggle (dau trinh) theory espoused by Vo Nguyen Giap but opposed by the politically oriented Truong Chinh. Pike said he could almost hear Truong Chinh saying, "You see, it's what I mean. You're not going to win militarily on the ground in the South. You've just proven what we've said; the way to win is in Washington." Alternatively, Giap, in September 1967, had written what might well have been a political dau trinh argument: the U.S. was faced with two unacceptable alternatives: invading the North or continue a stalemate. Invasion of "a member country of the Socialist camp" would enlarge the war, which Giap said would cause the "U. S. imperialists...incalculable serious consequences." As for reinforcements, "Even if they increase their troops by another 50,000, 100,000 or more, they cannot extricate themselves from their comprehensive stalemate in the southern part of our country." 
The answer may be somewhere in-between: Giap indeed wanted to draw American forces away from the coastal urban areas, but tried too hard for a victory at Khe Sanh. 
The "other war"1966 was the year of considerable improvement of command relationships, still under Westmoreland, for what Westmoreland considered the less interesting "other war" of rural development. There were frequent changes of names of aspects of this mission, starting in 1964, but eventually, the GVN and US agreed on the term Revolutionary Development (RD), which was to continue in a variety of development activities. The term, apparently coined by Premier and general Nguyen Cao Ky, was agreed to be defined as
RD is the integrated military and civil process to restore, consolidate and expand government control so that nation building can progress throughout the Republic of Vietnam. It consists of those coordinated military and civil actions to liberate the people from Viet Cong control; restore public security; initiate political, economic and social development; extend effective Government of Vietnam authority; and win the willing support of people toward these ends.
"Search and Destroy" gave way after 1968 to "clear and hold", when Creighton Abrams replaced Westmoreland.
Westmoreland was principally interested only in overt military operations, while Abrams looked at a broader picture. MACV advisors did work closely with 900,000 local GVN officials in a well-organized pacification program called CORDS (Civil Operations and Revolutionary Development.) It stressed technical aid, local self government, and land distribution to peasant farmers. A majority of tenant farmers received title to their own land in one of the most successful transfer projects in any nation. On the other hand, hundreds of thousands of peasants entered squalid refugee camps when CORDS moved them out of villages that could not be protected.
In the Phoenix Program (part of CORDS with a strong CIA component) GVN police identified and arrested (and sometimes killed) the NLF secret police agents engaged in assassination.
Fighting continues; 1964 winter offensive
Throughout the intensified war, it should be noticed the Vietnamese weather enforced seasonal offensives. Typically, there was a winter-spring offensive, from perhaps November to March, and a summer offensive, separated by rainy or monsoon seasons.
Since MACV-SOG covert operations were small-unit, weather was not a determining factor. started, although these were primarily psychological warfare at first. Planning for guerrilla operations in the North and, although no Americans knew the North Vietnamese fear of such, actions against the Trail in Laos were still denied. 
The February 1964 attack on U.S. forces at Kontum signaled a policy change; the North Vietnamese had previously not struck directly at Americans. As well as raids, terrorist attacks against Americans increased, in keeping with the changed political theory, or, as Truong Chinh put it, to "properly punish a number of reactionaries and tyrants who owe blood debts to the people."
In September 1964, North Vietnam sent a Politburo member, Nguyen Chi Thanh, to organize the effort in the south. The sending of a headquarters, however, is not obvious. North Vietnamese combat units started deploying in October, but, again, this was preparation. Reasonably, they wanted to know the outcome of the November 1964 Presidential election before assessing the potential for U.S. action. Both sides, in mid-1964, were misreading one another. On the U.S. side, the Defense Department's Joint War Gaming Agency conducted the Sigma II-64 war game in mid-September, which concluded that the full air attack program proposed by the JCS would not have a major effect. Neither bombing of the North itself, nor of the Ho Chi Minh trail, greatly threatened thinking in the Politburo. Unknown to the U.S., their greatest fear was a major ground operation to cut the trail, which, indeed, would have meant entering Laos and Cambodia. Dong Sy Nguyen, the North Vietnamese general running trail operations, was less concerned with bombing than
What worries me most is that they will send in troops or use choppers to send some commandos or drop paratroopers, who would then occupy a chunk of the trail. This would throw the entire complicated system out of whack.
1964-1965 winter offensive
If the Politburo had assumed the U.S. would not use airpower against the North, they were disabused by the outcome of a February 6, 1965 VC attack attacked U.S. facilities at Pleiku, killing 8 and destroying 10 aircraft. President Johnson, on February 7-8, responded with the first specifically retaliatory air raid, Operation FLAMING DART (or, more specifically, FLAMING DART I), of the broader Operation ROLLING THUNDER plan, which had not yet officially started. Alternatively, the North Vietnamese may have accepted the risk of being bombed, correctly predicting that even if ground troops were introduced, the U.S. would not risk the North's greatest fear: large-scale ground operations, beyond the South Vietnamese border, against the Ho Chi Minh trail.
The Pleiku attack seems to have been a vital decision point for the U.S. While the introduction of U.S. ground troops had been discussed for years, there were no specific plans. Bundy's memorandum to Johnson about the attack, on 7 February, did not propose the introduction of combat troops. 
Johnson made no public announcements, although the U.S. press reported it. The attack was carried out by U.S. Navy aviators from an aircraft carrier in the South China Sea. FLAMING DART II was a response to an attack on Qui Nhon on March 10. In response, initially unknown to the U.S., the North Vietnamese received their first S-75 Dvina (NATO reporting name SA-2 GUIDELINE) surface-to-air missiles, although civilian officials assumed they would not be used. In fact, the missiles were used, setting off upward spiral of air attack and air defense.
It must be emphasized that for most of the war, the bulk of the attacks on the North came, at first, from Navy carriers offshore. When the bombing escalated, they were joined by U.S. Air Force fighter-bombers flying from bases in Thailand. While there were occasional strikes on the DMZ and the southern part of the DRV from bases in the South, especially when South Vietnamese aircraft participated, the U.S. bases in the RVN primarily supported operations there. Da Nang was the primary South Vietnamese base for such strikes.
Bases in SVN, however, were accessible to the VC, by ground attack, or with rockets and mortars of only a few miles' range. As FLAMING DART progressed and the detailed planning for the major air escalation of ROLLING THUNDER, Westmoreland was concerned about the security of the exposed U.S. air bases in the south. On February 22, he sent his deputy, LTG John Throckmorton, to inspect the Marine aviation base at Da Nang; Throckmorton reported that a full Marine Expeditionary Brigade, with three infantry battalions and supporting elements, were needed to ensure its defense. Westmoreland, according to Davidson, believed a two-battalion MEB was more politically acceptable, but submitted that request.
The President approved sending two Marine battalions on February 26. Other than possibly Westmoreland, they were seen purely as defensive troops. Westmoreland denies assuming they would be available for missions outside the base. The Pentagon Papers suggest he did see a wider mission, but there is no strong evidence that he did. 
Ambassador Taylor, a retired general with extensive combat experience, objected. His calculation was that one battalion would protect the base from any plausible direct VC ground attack, but that six, not three, battalions would be necessary to establish a sufficiently large area to prevent the VC firing on Da Nang with standard and easily portable 81mm mortars. The Joint Chiefs of Staff disagreed, and forwarded Westmoreland's request, with their agreement, on 26 February.
ROLLING THUNDER buildup, March
Shortly before Johnson approved the sustained Operation ROLLING THUNDER plan on March 13, the Da Nang security force arrived on March 8. in response to Westmoreland's request of February 22 reflecting a concern with VC forces massing near the Marine air base at Da Nang, 3500 Marine ground troops arrived, the first U.S. large ground combat unit in Vietnam.
President Johnson ordered Chief of Staff of the Army GEN Harold Johnson to assess the situation, already doubting the air offensive before it seriously began. GEN Johnson reported, in Vietnam between March 5 and 12, reported back on 14 March. He was seriously concerned about the situation, and proposed external forces be brought in to free the ARVN for offensive action because "what the situation requires may exceed what the Vietnamese can be expected to do."  He proposed a U.S. division be sent preferentially to the Central Highlands (II Vietnamese corps area; Kontum, Pleiku, and Darlac provinces) or to the Bien Hoa/Tan Son Nhut area nearer to Saigon. McNamara, however, did not think such action would make enough ARVN troops available and preferred that a Republic of Korea division be sent rather than U.S. troops. GEN Johnson also suggested a four-division force be raised under the SEATO treaty and used to block infiltration.
GEN Johnson said a decision was needed "now to determine what the Vietnamese should be expected to do for themselves and how much more the U.S. must contribute directly to the security of South Vietnam." Secretary McNamara noted in the margin: "Policy is: anything that will strengthen the position of the GVN will be sent..."
Carrot and Stick, April
Johnson's main public announcement at the time, however, was an April 7 speech, in which he offered economic support to North Vietnam, and Southeast Asia in general, if it would stop military action.  This offer was quite in keeping with his goals for development, the Great Society, in the United States, and was likely a sincere offer. That he saw such an offer as attractive to the enemy, however, is an indication of his lack of understanding of the opposing ideology.
As this proposals were made to the North, on 13 April 1965, joint RVN-US discussions agreed that the ARVN force levels were inadequate. The manning level was increased, to increase RVN infantry battalions from 119 to 150. The new battalions were generally added to existing regiments, to avoid the need of creating more headquarters units. By the end of 1965, twenty-four were either in the field or in training areas.
The Director of Central Intelligence, wrote to McNamara and others that the ROLLING THUNDER campaign was not a serious deterrent to the DRV, and warned against putting more U.S. troops into combat roles. McCone said that this would merely encourage the Soviets and Chinese to take a low-risk course of supporting infiltration.
In April, Johnson changed the rules of engagement to permit the Marines to go beyond static defense, and to start offensive sweeps to find and engage enemy forces.
RVN reverses in May
A VC unit, estimated to be in two-regiment strength, fought the Battle of Song Be, the capital of Phuoc Long province, about 100 miles from Saigon, on 11 May. Much farther in the north, later in the month, they ambushed an ARVN force in the north, near Quang Ngai, badly hurting ARVN relief troops and leaving two battalions combat ineffective.
Westmoreland obtained Taylor's agreement on a plan for reinforcement. It had three phases, the first two establishing security for Allied bases and then an offensive strategy, beginning with enclaves on the cost, and moving inland.
- The first phase extended the security perimeter of the bases so that the facilities were out of range of light artillery. I
- U.S. forces, in coordination with the RVN, would make deep patrols and limited offensives, still centered on the bases, to pre-empt direct threats.
- "Search and destroy plus reserve reaction operations."
Westmoreland assumed he would have III Marine Expeditionary Force, the new airmobile division, a Republic of Korea division replacing the Marines in central Vietnam, and the 173rd Airborne Brigade for the Bien Hoa/Vung Tau area near Saigon. Early, CINCPAC had objected to the use of the 173rd, since it was the primary strategic reserve for Pacific Command.
U.S. decision to escalate
Westmoreland, in early June, saw the situation as close to collapse without a major commitment of ground troops, in addition to the ARVN. This triggered several weeks of intense debate among the President's close civilian advisers, with McNamara controlling all direct military input to the process.There were two drivers among the inner circle. First, some, but not all, were fervent believers in the containment doctrine, especially Rusk. McNamara quoted Rusk's direct appeal to Johnson:
The integrity of the U.S. commitment is the principal pillar of peace throughout the world. If that commitment becomes unreliable, the communist world would draw conclusions that would lead to our ruin and almost certainly to a catastrophic war. So long as the South Vietnamese are prepared to fight for themselves, we cannot abandon them without disaster to peace and to our other interests throughout the worldSecond, the principals viewed the situation with their own experiential and analytical filters, well articulated by Ball in an oral history interview.
McNamara was analyzing this thing as a man who was trained in quantification, who believed in systems analysis, who believed in application of games theory to strategy, who was enormously persuaded by the disparity in military power... Rusk, it was quite a different thing. He was enormously influenced by his experience during the Korean War. Mac Bundy saw this as a fascinating set of operational problems. I think he assumed that we were so clever, somehow we could find the key hook. For myself, I had a whole different set of experiences. As a practicing lawyer, I had had among my clients various agencies of the French government when they wentthrough the Indo-Chinese experience. I had heard everything before.
Johnson gave the go-ahead in July, but then sent McNamara and others to study actions further.
May and June Combat
Mid-May saw a new series of Communist offensives, all over the country. Much of the action was in Phuoc Long province, 50 miles northeast of Saigon near the Cambodian boarder. Its capital, Song Be, was overrun. Song Be was primarily defended by irregular ARVN units, although supported by a Special Forces team and several miscellaneous units. An unprecedented amount of air support, including the first use of a company-sized armed helicopter unit, allowed a successful defense. Higher command, however, was concern that this large a VC unit could take an initiative.
On June 10, the VC made another two-regiment attack on Dong Xoai, north of Saigon, using one regiment against the town and Special Forces camp, while preparing an ambush for an ARVN relief force with the other. ARVN leadership disintegrated, and, contrary to policy, American advisers took command. The VC ambushes were extremely effective against ARVN relief forces, which were committed one battalion at a time, until the ARVN ran out of reserves. Among the forces destroyed was the 7th Airborne Battalion, one of the best units in the ARVN.
The 44 battalion request
Westmoreland, on June 7, sent a message to CINCPAC that a VC summer offensive was underway, not yet at its full potential, both to destroy RVN forces and isolate (but not hold) key towns.  He doubted the South Vietnamese capability to cope was in grave doubt, largely due to recent troop losses. To prevent what he called collapse, he wanted to double the size of his forces, with 34 U.S. and 10 South Korean battalions comprising 175,0000 men; thus the message has been called the "44 battalion request." The State Department's Bureau of Intelligence and Research disagreed with the MACV assessment of near-collapse. 
Even then, he told Lyndon Johnson, they would be a stopgap, with at least 100,000 more needed in 1966. For Johnson, it was a choice between deeper involvement or defeat. McNamara said this cable was the most disturbing of the war; it forced a major decision and discussions with the President on the 9th and 10th. In a telephone conversation afterwards, McNamara told Johnson that he personally had limitations in mind, but he did not think that the Joint Chiefs of Staff had them. Still, McNamara briefed the press on the 16th. Polls supported the escalation, and, when asked for his advice, Dwight D. Eisenhower agreed that the reinforcements should be sent.
Discussion before decision
Considerable internal discussion took place among the President's key civilian advisers, with the main four papers presented to Johnson on July 1, with a covering memo from Assistant to the President for National Security Affairs, McGeorge Bundy. George Ball was the most strongly opposed to escalation. Ball had been, since October 1964, had been sending Johnson memoranda saying "we should cut our losses."
William Bundy ruled out withdrawal, but did not think escalation would help, unless the ARVN did netter; he was concerned that too large an intervention would create a "white man's war", with the U.S. replaying the role of the French in the endgame in Indochina.  Ball, in his oral history interview, deprecated William Bundy's influence, "he was not one of the top three or four people that were always talking to the President about these things.
It is clear that no military personnel were part of the inner circle of discussion, but there are different descriptions of the degree to which they were consulted. McNamara said "I spent countless hours with the Joint Chiefs" debating Westmoreland's thinking.  McNamara did have a small staff group, headed by John McNaughton, who obtained technical assistance from the Joint Staff, but did not have participation from the JCS proper. McMaster, however, cites George Ball as saying that McNamara lied to the Chairman of the Joint Chiefs of Staff, Earle Wheeler, to ensure that Wheeler did not attend the meeting when the Ball and McNamara drafts were reviewed.
Congress, as an institution, also was not consulted. Johnson believed the Gulf of Tonkin resolution gave him all the authority he needed, and, indeed, Senators both opposed and supporting the escalation did not believe it was a proper matter for Congressional debate. Much later, McNamara wrote that it was wrong not to have that debate, even if it encouraged the enemy. .
Decision and worry
Before the July 1, 1965 presentation to Johnson,McGeorge Bundy suggested that he "listen hard to George Ball and then reject his proposal," and pick between McNamara's and William Bundy's recommendations; McNamara would "tone down" his recommendations. 
At Defense, McNamanara agreed the situation was worse, but believed the situation might be retrieved: "The situation in SVN is worse than a year ago (when it was worse than a year before that). After a few months of stalemate, the tempo of the war has quickened. . . . The central highlands could well be lost to the NLF during this monsoon season. Since June 1, the GVN has been forced to abandon six district capitals; only one has been retaken...The odds are less than even that the Ky government will last out the year. Ky is "executive agent" for a directorate of generals."
McNamara also observed that the Administration's approach to air war against the North, Rolling Thunder, had not "produced tangible evidence of willingness on the part of Hanoi to come to the conference table in a reasonable mood. The DRV/VC seem to believe that SVN is on the run and near collapse; they show no signs of settling for less than complete takeover."
1965-1966 winter-spring offensive
There was an increasing intensity to use air power in Cambodia and Laos, accelerating in July. In some, but not all cases, the Cambodian or Laotian governments were secretly consulted, but in other cases, U.S. aircraft, especially B-52 bombers acted at direct U.S.
VC attacks ranged in size from local bombings to multi-regimental operations, and use of longer-range artillery.
The Battle of the Ia Drang, beginning in November 1965, was a response to the start of the 1965-1966 Communist winter-spring offensive; the Battle of Bong Son was effectively a continuation a month later. These were significant for a variety of reasons, first because the Communists first used a division-sized organization in conventional warfare, and second the U.S. first used true airmobile forces, also in division strength, in response. The Ia Drang also involved the first use of B-52 bombers integrated into a tactical plan, rather than on independent ARC LIGHT missions.
Starting on the December 20, 1965, the non-Communist forces held an 84-hour ceasefire for Tet, which was the culmination of a psychological warfare program to encourage Communist defections under the Chieu Hoi program. MACV announced 106 Communist violations of the truce.
Starting in mid-February 1966, patrols detected indications of a pending VC attack against the A Shau Special Forces camp, whose mission was surveillance of infiltration from the nearby Laotian border. Continuous attacks on 9-10 March overran the camp, with a disorderly retreat losing several helicopters and resulting in a number of friendly personnel missing in action.
To act before the 1966-1967 Communist offensive, Operation ATTLEBORO, starting in November 1965, was the first of many "search and destroy" missions launched by the U.S., such as Operation JUNCTION CITY anf Operation CEDAR FALLS
In 1967, the NVA organization in the northwest was under two Military Regions (MR), MR-4 north and south of the DMZ, and MR-5 (also known as MR-S) for Communist units in the northern part of South Vietnam. Essentially, the MR-4 command was conventional while MR-5 was guerrilla. MR-4 commanded five divisions north of the DMZ, three operational, one reserve, and one recovering from battle.
1967-1968 North Vietnamese offensive
1968 began with the Tet offensive, which caused immense Communist losses.
By mid-January 1968, III MAF was the size of a U.S. corps, consisting of what amounted to two Army divisions, two reinforced Marine Divisions, a Marine aircraft wing, and supporting forces, numbering well over 100,000. GEN Westmoreland believed that Marine LTG Robert E. Cushman, Jr., who had relieved General Walt, was "unduly complacent." worried about what he perceived as the Marine command's "lack of followup in supervision," its employment of helicopters, and its generalship.  Westmoreland sent his deputy Creighton Abrams to take command of I Corps, and gave his Air Force commander control of Marine aviation. The Marines protested vehemently but were rebuffed by the Joint Chiefs of Staff. 
GEN Cushman, formerly the III Marine Amphibious Corps commander in Vietnam and, in 1969, Commandant of the Marine Corps,  said "I felt, and I think that most Marines felt, that the time had come to get out of Vietnam."
Subsequent actions in April and May were more holding actions than anything decisive; again, the goal may have been simply to pin forces while affecting American public opinion and politics. The North Vietnamese 320th Division fought the U.S. 3rd Marine Division i the area north of Dong Ha, resulting in heavy NVA casualties. 
Starting in June, Marine operations made more extensive use of artillery fire support bases, a variant on typical Marine Air-Ground Task Force doctrine that tends to use air rather than substantial artillery. The 3rd would usually relocate an infantry battalion command post with the firebase, from which the infantry companies would move by foot or helicopter.
The 320th, in August, again moved against the 3rd, south of the Ben Hai River and north of Route 9, between Cam Lo and the Rockpile.
North Vietnamese actions certainly were dependent on the result of the U.S. 1968 Presidential election, and what they saw as a new environment under Nixon. Several factors caused change in U.S. strategy:
- There was no plausible way of inflicting a decisive defeat with the politically plausible forces
- Communist forces had taken massive casualties
- The South Vietnamese were better mobilized and organized than ever before.
It was the decision of the Nixon Administration, therefore, to start Vietnamization, or turning over ground combat to the South Vietnamese.
- Bureau of Intelligence and Research, U.S. Department of State, IV. Time of Decision: November 1963-March 1965, Vietnam 1961-1968 as interpreted in INR's Production, vol. George Washington University National Security Archive Electronic Briefing Book No. 121, INR-VN4, pp. 10-18
- Tran Van Tra (1993), Tet: The 1968 General Offensive and General Uprising, in Jayne S. Werner and Luu Doan Huynh, The Vietnam War: American and Vietnamese Perspective, M.E. Sharpe, Tran Van Tra-Tet, pp. 38-40
- Robert S. McNamara (1995), In Retrospect: the Tragedy and Lessons of Vietnam, Times Books division of Random House, p. 112
- Mao Tse-tung (1967), On Protracted War, Foreign Languages Press, pp. 175-176
- Carland, John M. (2004), "Winning the Vietnam War: Westmoreland's Approach in Two Documents.", Journal of Military History 68 (2): 553-574
- Palmer, Dave R. (1978), Summons of the Trumpet, Presidio Press, pp. 63-65
- Hanyok, Robert J. (2002), Chapter 7 - A Springtime of Trumpets: SIGINT and the Tet Offensive, Spartans in Darkness: American SIGINT and the Indochina War, 1945-1975, Center for Cryptologic History, National Security Agency, p. 310
- Douglas Pike (June 4, 1981), Oral History interview by Ted Gittinger, Lyndon Baines Johnson Presidential Library, pp. I-1 to I-3
- Tran Van Tra-Tet, pp. 38-40
- The Marines in Vietnam, 1954-1973: An Anthology and Annotated Bibliography (Second Printing, 1985 ed.), History and Museums Division, United States Marine Corps, 1974, p. 97
- Marc Jason Gilbert and William Head, ed. (1996), The Tet Offensive, Greenwood Publishing Group, Inc.
- Eckhardt, George S. (1991), Vietnam Studies: Command and Control 1950-1969, Center for Military History, U.S. Department of the Army, pp. 64-68
- Thomas W. Scoville, Reorganizing for pacification support (1982) online edition
- Shultz, Richard H., Jr. (2000), the Secret War against Hanoi: the untold story of spies, saboteurs, and covert warriors in North Vietnam, Harper Collins Perennial, pp. 41-45
- Palmer, p. 51
- Moyar, Mark (2006), Triumph Forsaken, Cambridge University Press, p. 326
- McNamara, p. 153
- Moyar, pp. 323-324
- Davidson, Phillip B. (1991), Vietnam at War: The History: 1946-1975, Oxford University Press USp. 342
- Davidson, p. 344
- , Chapter 4, "American Troops Enter the Ground War, March-July 1965," Section 1, pp. 389-433, The Pentagon Papers, Gravel Edition, Volume 3
- PntV3Ch4389-433, EMBTEL (Embassy Telegram) of 22 February 1965
- Lyndon B. Johnson (April 7, 1965), speech at Johns Hopkins University
- Collins, James Lawton, Jr., Chapter I: The Formative Years, 1950-1959, Vietnam Studies: The Development and Training of the South Vietnamese Army, 1950-1972, p. 64
- , Chapter 1, "U.S. Programs in South Vietnam, Nov. 1963-Apr. 1965,"Section 1, pp. 1-56, The Pentagon Papers, Gravel Edition, Volume 3
- Dean Rusk, quoted by McNamara, p. 195
- Ball, pp. I-20 to I-21
- Unit History of the 334th Armed Helicopter Company
- Karnow, pp. 421-422
- MACV cable 19118, Westmoreland to Sharp and Wheeler "Deployment", quoted in McNamara, pp. 187-188
- Bureau of Intelligence and Research, U.S. Department of State, V - Trial by Force: March 1965-February 1965, Vietnam 1961-1968 as interpreted in INR's Production, vol. George Washington University National Security Archive Electronic Briefing Book No. 121, INR-VN5, p. 10
- Ball, I-11
- Karnow, pp. 423-424
- Ball, p. I-13
- McNamara, p. 192
- McMaster, pp. 301-302
- McMaster, p. 411
- McNamara, pp. 191-192
- McMaster, p. 302
- McNamara, Robert S. (20 July 1965), Notes for Memorandum from McNamara to Lyndon Johnson, "Recommendations of Additional Deployments to Vietnam,"
- Telfer, Gary L.; Lane Rogers & V. Keith, Jr. Fleming (1984), U.S. Marines in Vietnam: Fighting the North Vietnamese, 1967, History and Museums Division, United States Marine Corps
- Westmoreland, William, A Soldier Reports
- Shulimson, Jack, The Marine War: III MAF in Vietnam, 1965-1971, U.S. Marine Corps Historical Center,
- Westmoreland, William C. (1976), A Soldier Reports, pp 164-66
- Krulak, Victor, First to Fight, pp 195-204 online
- The War Managers American Generals Reflect on Vietnam, 1991, pp. 60-61
- Brazier, R. C. (1974), DEFEAT of the 320th, The Marines in Vietnam, 1954-1973: An Anthology and Annotated Bibliography (Second Printing, 1985 ed.), History and Museums Division, United States Marine Corps, p. 164