In the spring and early summer of 1965, U.S. ground troops began their first tentative patrols into the South Vietnamese countryside. The purpose of these patrols was four-fold: 1) to keep the Vietcong away from U.S. bases; 2) to ensure the safe arrival of American reinforcements at the American-occupied coastal enclaves; 3) to familiarize U.S. troops with South Vietnam’s varied environments; 4) and to experiment with tactics.
Several top policymakers in the Johnson administration favored a period of tactical experimentation, believing such experimentation could help the White House decide whether to commit the United States to a large-scale ground war in South Vietnam.
Maxwell Taylor, who served as U.S. Ambassador to South Vietnam in early 1965, became a proponent of tactical experimentation because he doubted that U.S. troops could succeed in a counter-insurgency role in rural South Vietnam. Taylor verbalized his concerns in a conversation with Defense Secretary Robert S. McNamara in March. McNamara later recounted the conversation to President Johnson, “…Max believes that U.S. troops would have great difficulty operating in South Vietnam – particularly in a counter-guerrilla role, where they’d be operating by themselves in the countryside. They’d have difficulty in distinguishing Vietcong from Vietnamese, be attacking South Vietnamese villages, make mistakes and kill loyal South Vietnamese people…He says that our troops…are poorly trained as counter-guerrillas.” Taylor worried that U.S. troops, wholly ignorant of Vietnamese cultural norms, would only spur the insurgency, rather than squash it.
Presidential adviser George Ball became the strongest advocate of tactical experimentation. In a June 18, 1965, memo to the president, he argued that the roughly 15,000 combat troops then in South Vietnam should operate on a trial basis until the end of the rainy season in October. At that point, the administration could evaluate the tactical successes and failures of those troops before authorizing additional reinforcements. Ball wrote, “I propose that we also treat the monsoon season as a test period since we do not yet have enough experience with the direct employment of American combat forces to appraise our chances for military success in the South.”
Ball believed that if the tactical experimentation phase showed that U.S. troops could not find the enemy, had trouble operating in South Vietnam’s rice paddies, heat, and monsoonal rains, and that the South Vietnamese population viewed the U.S. troops as foreign invaders, similar to the French in the 1940s and 1950s, then Johnson would be wise to cap the U.S. troop build-up at 100,000 men. Ball further argued that 100,000 troops would provide the U.S. with the necessary leverage to negotiate with the Communists a compromise political settlement for South Vietnam. In other words, the Communists would have to come to the table to talk to the U.S. since they could not easily push 100,000 U.S. troops out of Vietnam. Ball’s compromise settlement with Hanoi consisted of two components: 1) a coalition government in Saigon that included Communists within its ranks, and; 2) possible neutralization of South Vietnam as a precursor to eventual Communist control of the country.
Ball ended his memo to President Johnson by stating, “…on the basis of our experience during that trial period we will then appraise the costs and possibilities of waging a successful land war in South Viet-Nam and chart a clear course of action accordingly….” For Ball, the outcome of the tactical experimentation would guide future U.S. decisions with regard to South Vietnam, especially whether to negotiate and get out or escalate and go further in.
National Security Adviser McGeorge Bundy, his brother William, who served in the State Department, as well as retired General John Gavin, all believed that a tactical experimentation phase would assist the U.S. in determining the best overall war strategy – especially whether American troops should be assigned a counter-insurgency role or a more traditional conventional military role.
During the first months of the U.S. troop build-up in the spring of 1965, American war planners considered five strategy options for a potential U.S. ground war in South Vietnam: 1) a counter-insurgency strategy; 2) an enclave strategy; 3) a combination enclave and counter-insurgency strategy – known as the “oil spot” approach; 4) an enclave strategy with a mobile reserve force; and 5) a hinterland strategy that emphasized the destruction of enemy main forces in remote areas of South Vietnam. Each strategy had its adherents, each had its pros and cons, and each had its own unique geographical characteristics.
Unfortunately for the Americans, two events in early- and mid-1965 precluded any tactical experimentation. One was the Vietcong’s spring lull and the other was the Communists’ rainy season offensive.
The lull in Vietcong military activity from mid-March to late May made it difficult for the U.S. to draw any lessons from its initial, limited involvement in the ground war. For reasons that are not entirely clear, the Vietcong did little to thwart the U.S. troop build-up or the deployment of U.S. troops on the immediate environs of the coastal enclaves. American units established themselves at their base sites largely unopposed. And although local guerrillas did take potshots at the GIs setting up their tents or digging foxholes on the edges of their bases, no Vietcong main forces launched any full-scale attacks against the U.S. enclaves or the small American infantry units patrolling near the big U.S. bases.
The lull may have been designed to conserve Vietcong strength for their upcoming monsoon offensive, set to begin in May. Or maybe the Communists used the lull to observe U.S. tactics, weapons, and equipment in order to more effectively counter the new enemy they found in their midst. Hanoi may also have held back its forces in the South in order not to provoke the U.S. into a full-scale ground war. It’s quite possible North Vietnamese leaders adopted a wait-and-see approach to the increasing American presence, hoping the Americans would recognize the difficulties of conducting military operations in South Vietnam and decide to stay put on their big bases, leaving the field of battle to the Vietcong and the South Vietnamese Army.
There was another possible reason for the lull: Hanoi decided that sending its hardened main forces against green U.S. units would lead to high U.S. casualties. Those American casualties would in-turn put domestic political pressure on President Johnson to massively escalate both the ground war and the air war over the North, two outcomes that Hanoi wanted to avoid.
One final explanation for the lull related to the air war across the South. The intensified U.S. bombing of rural South Vietnam since February had thrown the Vietcong off-balance and hindered its ability to counter the American build-up. One of the anonymous authors of the Pentagon Papers believed the major increase in U.S. airstrikes had contributed to the lull, “The Vietcong were unusually inactive throughout March and April…it was assumed that he was merely pausing to regroup and to assess the effect of the changed American participation in the war embodied in air strikes and in the Marines.” In many respects, the spring lull resembled round one of a boxing match as both contenders danced around the ring trying to get a feel for their opponent’s strengths and weaknesses.
In late May the lull came to an abrupt end. The Vietcong began their monsoon offensive by first isolating Danang. On May 24, 1965, the guerrillas blew up four bridges and two culverts along the rail line between Danang and Hue. A week later, a Vietcong force, estimated at five battalions, destroyed two ARVN battalions and an elite Ranger battalion at Ba Gia, near Quang Ngai City. The ARVN lost 350 dead and 350 wounded at Ba Gia. Then, in the last week of May, Vietcong main forces went into action all across South Vietnam, methodically chewing up the demoralized, and increasingly panic-stricken, South Vietnamese Army. General Westmoreland speculated that the Communists hoped to bring about South Vietnam’s collapse before U.S. troop reinforcements could rescue it.
At a news conference on June 1, 1965, President Johnson commented on Saigon’s recent military reverses, “Suffice it to say … I think it has been serious. We are concerned about it ….It has been occupying our attention.” Two days later the South Vietnamese suffered another crushing defeat, this time in the Central Highlands. In an ambush at Phu Bien, fifty miles southeast of Pleiku, the Vietcong decimated yet another ARVN battalion, inflicting 220 casualties. All across the highlands the ARVN fell back, unable to halt the Communist onslaught. An exasperated U.S. military adviser commented on what appeared to be an unstoppable rout of the ARVN, “The VC are coming out of the bloody hills …We’re barely holding our own.”
In one five-day period of fighting in late May and the first days of June, the South Vietnamese suffered 1,000 casualties. But ARVN losses did not stop there. Convinced that the war’s momentum had swung decisively in their favor, the Vietcong kept up the pressure. In the first week of June, hundreds of ARVN soldiers died in Vietcong attacks. In the second week of June, the South Vietnamese suffered 1,672 casualties, the largest one-week casualty rate of the war to date.
The destruction of so much South Vietnamese combat power in such a short period of time set off alarm bells in Saigon and Washington. South Vietnamese military commanders told their American counterparts that the ARVN would not survive the present round of fighting unless the United States became fully engaged in ground combat operations against the Vietcong. And if the South Vietnamese military, and by implication the Government of South Vietnam, were to survive the year, the U.S. needed to abandon its defensive posture around its bases and send its troops immediately into the countryside to search out and destroy the Communist main forces – the very units that were scoring so many dramatic successes against the ARVN. U.S. military officials in Saigon agreed with their South Vietnamese counterparts – the ARVN was on the ropes and only U.S. combat troops and airpower could halt the South’s looming collapse.
Never one to express alarm, Westmoreland came close to doing just that in three telegrams to his superiors in Honolulu and Washington. On June 7, he wrote CINCPAC Admiral Grant Sharp Jr., “…the GVN cannot stand up successfully to this kind of pressure without [U.S.] reinforcement.” That same day Westmoreland informed the Joint Chiefs of Staff, “ARVN forces…are already experiencing difficulty in coping with this increased VC capability. Desertion rates are inordinately high. Battle losses have been higher than expected…effective fighting strength of many infantry and ranger battalions is unacceptably low.” An estimated 10,000 troops, or the equivalent of ten battalions, were deserting the ARVN every month. Five days later, Westmoreland telegraphed Sharp again “…the time has come when such [U.S.] support is essential to the survival of any government of South Vietnam and the integrity of the RVNAF.” According to Westmoreland, American troops had to actively pursue the Vietcong and North Vietnamese regulars or the South would fall. The general continued, “We have reached a point in Vietnam where we cannot avoid the commitment to combat of U.S. ground troops. Our objective is to maintain intact the Government of South Vietnam and its armed forces. They can no longer cope alone with the increased VC/DRV threat.”
To prevent the ARVN’s disintegration, and ultimately the loss of South Vietnam, Westmoreland asked Sharp for the authorization to expand the Tactical Area of Responsibility (TAOR) of U.S. units. At the start of the monsoon offensive, U.S. ground combat units had authority to operate only on the environs of U.S. bases. Westmoreland wanted the TAORs expanded to include all known Vietcong base areas. He informed Sharp that the extension of the TAORs would protect U.S. installations and prevent the Vietcong from concentrating their forces against the U.S. enclaves. Although couched in defensive terms, Westmoreland was in-fact asking for the authority to go on the offensive all across South Vietnam, since Vietcong base areas existed throughout the country.
Westmoreland made it appear that the protection of U.S. bases served as the primary reason he needed the TAOR extension, when in reality he wanted the TAORs expanded across South Vietnam in order for U.S. troops to fully engage in offensive operations against the Vietcong and North Vietnamese Army. By framing the TAOR extension as a defensive measure, Westmoreland made it hard for President Johnson to reject the request. Had the president ruled against Westmoreland, he might later face accusations that he impaired the ability of a field commander to defend his troops against large, menacing enemy formations, something few presidents have ever been willing to do. Johnson understood that a rejection of the TAOR request had the potential to come back and haunt him, especially if the Vietcong main forces succeeded in inflicting massive casualties on the U.S. troops stationed at one of the enclaves. And yet the president, who already leaned toward a greater U.S. role in the ground war, recognized that Westmoreland’s request also provided him with the political cover to pursue an expanded U.S. role in the war. By meeting the needs of his field commander, Johnson removed some of the onus for the U.S. escalation in the South from his own shoulders and made it the responsibility of Westmoreland.
Johnson also recognized that had Westmoreland’s TAOR request been framed as a necessary step to save the South Vietnamese (which in fact it was), it would have been less appealing to the public, to Congress, and to the doubters and naysayers in the Department of Defense who wanted to avoid a major ground war in Southeast Asia. The opponents of U.S. escalation argued that only the South Vietnamese could save South Vietnam; no foreign, white military force could do the job for them. On the other hand, Westmoreland and Johnson both knew that the opponents of major U.S. involvement in South Vietnam would find it difficult, if not impossible, to criticize a decision to protect the U.S. forces already in harm’s way by expanding the TAORs.
In the end, Johnson rationalized a major U.S. escalation in the ground war as a necessary step to ensure the safety of the U.S. forces already in the country. He had been using this justification since March when he sent the Marines to Danang to protect the aircrews and aircraft at the airbase there. Now he used the same justification to send U.S. troops against the Communists’ main forces. Interestingly, at the height of the Tet Offensive two and a half years later, Johnson would use the very same argument yet again to justify a further increase in U.S. troop levels in South Vietnam. And at the end of his administration in January 1969, LBJ would go so far as to claim that he could not begin a U.S. troop withdrawal from South Vietnam without endangering the half million troops still in-country.
On June 26, 1965, Johnson approved Westmoreland’s request to expand the TAORs in South Vietnam. The President gave Westmoreland the authority to commit U.S. troops to combat, “…in any situation in which the use of such troops is required by an appropriate GVN commander and when, in COMUSMACV’s judgment, their use is necessary to strengthen the relative position of GVN forces.” This authorization went beyond Westmoreland’s proposal to expand the TAORs to protect U.S. bases. The U.S. was now going to war to prevent the total collapse of the ARVN and GVN. On the very next day, U.S. troops conducted their first publicly-acknowledged offensive operation in the South Vietnamese countryside. That patrol marked the official beginning of the U.S. ground war in South Vietnam.
The Vietcong lull, and Johnson’s decision to send U.S. ground units directly into combat against Communist forces all across South Vietnam, precluded any further American tactical experimentation. As a result, American military commanders never had a chance to learn the lessons that could have informed both the pace and scale of the U.S. troop build-up or the development of a ground war strategy.
However, the lull and the monsoon offensive did provide one very important strategic insight, one with huge ramifications for the ultimate outcome of the U.S. military effort in South Vietnam – the Communists controlled the tempo of combat operations in the South. They could turn the war on or they could turn it off. They could keep their casualties low or they could let their casualties increase. They held the strategic initiative. Surprisingly, this crucial lesson was lost on Westmoreland. He either did not recognize the importance of it, or if he did recognize it, he considered it irrelevant, believing in due time he would wrest the strategic initiative from the enemy; he would determine the tempo of the war; he would set the rate of Communist attrition; and he would win the war.
 Foreign Relations of the United States, 1964-1968, Volume II, Vietnam, January-June 1965, “Document 251, Editorial Note,” (Washington: GPO, 1996), 553; Foreign Relations of the United States, 1964-1968, Volume II, Vietnam, January-June 1965, “Document 261, Telegram From the Embassy in Vietnam to the Department of State, April 17, 1965,” (Washington DC: GPO, 1996), 570.
 Michael Beschloss, Reaching for Glory: Lyndon Johnson’s Secret White House Tapes, 1964-1965, (New York: Touchstone, 2001), 258.
 Foreign Relations of the United States, 1964-1968, Volume III, Vietnam, June-December, 1965, “Document 7, Memorandum From the Under Secretary of State (Ball) to President Johnson, June 18, 1965,” (Washington: GPO, 1996), 16.
 Ibid., 17..
 Foreign Relations of the United States, Vietnam, Volume III, June-December 1965, “Document 35, Memorandum From the President’s Special Assistant for National Security Affairs (Bundy) to Secretary of Defense McNamara, June 30, 1965″ (Washington: GPO, 1996), 91; Foreign Relations of the United States, Vietnam, Volume III, June-December 1965, “Document 41, Memorandum by the Assistant Secretary of State for Far Eastern Affairs (Bundy), July 1, 1965″ (Washington: GPO, 1996), 115.
 The Senate Gravel Edition, The Pentagon Papers, The Defense Department History of United States Decisionmaking on Vietnam, Volume III, (Boston: Beacon Press, 1971), 434.
 Foreign Relations of the United States, 1964-1968, Volume II, Vietnam, January-June 1965, “Document 243, Telegram From the Embassy in Vietnam to the Department of State, April 7, 1965,” (Washington DC: GPO, 1996), 540; Foreign Relations of the United States, 1964-1968, Volume II, Vietnam, January-June 1965, “Document 277, Telegram From the Embassy in Vietnam to the Department of State, April 28, 1965,” (Washington DC: GPO, 1996), 612; Foreign Relations of the United States, 1964-1968, Volume II, Vietnam, January-June 1965, “Document 290, Telegram From the Embassy in Vietnam to the Department of State, May 11, 1965,” (Washington DC: GPO, 1996), 633; Foreign Relations of the United States, 1964-1968, Volume II, Vietnam, January-June 1965, “Document 347, Summary of Notes of the 552d Meeting of the National Security Council, June 11, 1965,” (Washington DC: GPO, 1996), 757.
 New York Times, “Reds Cut Vital Railway,” May 25, 1965.
 New York Times, “Saigon’s Losses Worry President,” Jack Raymond, June 2, 1965.
 New York Times, “Vietcong Ambush Battalion Twice: Most of 300 Believed Lost in Attacks Near Pleiku,” Jack Langguth, June 4, 1965.
 Gravel Edition, Pentagon Papers, Volume III, 440.
 New York Times, “U.S. Officer Sees G.I. Combat Role in Vietnam Soon,” Jack Langguth, June 5, 1965.
 Gravel Edition, Pentagon Papers, Volume III, 439.
 Foreign Relations of the United States, 1964-1968, Volume II, Vietnam, January-June 1965, “Document 337, Telegram From the Commander, Military Assistance Command, Vietnam (Westmoreland) to the Joint Chiefs of Staff, June 7, 1965,” (Washington DC: GPO, 1996), 734.
 Foreign Relations of the United States, 1964-1968, Volume II, Vietnam, January-June 1965, “Document 340, Memorandum for the Record, June 8 1965,” (Washington DC: GPO, 1996), 740.
 Foreign Relations of the United States, Vietnam, Volume II, January – June 1965, “Document 351, Telegram from the Commander, Military Assistance Command, Vietnam (Westmoreland) to the Commander in Chief, Pacific (Sharp), Saigon, June 12, 1965,” (Washington: GPO, 1996), 774.
 Ibid., 772-774.
 Gravel Edition, Pentagon Papers, Volume III, 415.