Tet Offensive

Background

South Vietnam political context

The years prior to the Tet Offensive were marked by political instability and a series of coups after the 1963 South Vietnamese coup. In 1966, the leadership in South Vietnam, represented by the Head of State Nguyễn Văn Thiệu and Prime Minister Nguyễn Cao Kỳ were persuaded to commit to democratic reforms in an effort to stabilize the political situation during a conference in Honolulu. Prior to 1967, the South Vietnamese constituent assembly was in the process of drafting a new constitution and setting eventual elections. After the 1967 South Vietnamese presidential election, the South Vietnamese political situation looked increasingly stable. Rivalries between the generals were becoming less chaotic, and Thiệu and Kỳ formed a joint ticket for the election. Despite efforts by North Vietnam to disrupt elections, higher than usual turnouts marked a shift towards a more democratic structure and ushered in a period of political stability after the instability that had characterized the preceding years.

Protests, campaigning, and the atmosphere of elections were interpreted by the Politburo of the Communist Party of Vietnam and Lê Duẩn as signs the population would embrace a 'general uprising' against the government of South Vietnam. The Politburo sought to exploit perceived instability and maintain political weakness in South Vietnam.

United States war strategy

During late 1967, the question of whether the U.S. strategy of attrition was working in South Vietnam weighed heavily on the minds of the American public and the administration of President Lyndon B. Johnson. General William C. Westmoreland, the commander of the Military Assistance Command, Vietnam (MACV), believed that if a "crossover point" could be reached, meaning the number of communist troops killed or captured during military operations exceeded those recruited or replaced, the Americans would win the war. There was a discrepancy, however, between the order of battle estimates of the MACV and the Central Intelligence Agency (CIA) concerning the strength of VC guerrilla forces within South Vietnam. In September, members of the MACV intelligence services and the CIA met to prepare a Special National Intelligence Estimate that would be used by the administration to gauge U.S. success in the conflict.

Provided with an enemy intelligence windfall collected during Operations Cedar Falls and Junction City, the CIA members of the group believed the number of VC guerrillas, irregulars, and cadre within the South could be as high as 430,000. The MACV Combined Intelligence Center, on the other hand, maintained the number could be no more than 300,000. Westmoreland was deeply concerned about the possible perceptions of the American public to such an increased estimate since communist troop strength was routinely provided to reporters during press briefings. According to MACV's chief of intelligence, General Joseph A. McChristian, the new figures "would create a political bombshell", since they demonstrated the North Vietnamese "had the capability and the will to continue a protracted war of attrition".

In May, MACV attempted to reach a compromise with the CIA by maintaining VC militias did not constitute a fighting force but were essentially low-level fifth columnists used for information collection. With the groups deadlocked, George Carver, CIA Special Assistant for Vietnam Affairs, represented the CIA in the last stage of the negotiations. In September, Carver devised a compromise: The CIA would drop its insistence on including the irregulars in the final tally of forces and add a prose addendum to the estimate explaining the agency's position. George Allen, Carver's deputy, placed responsibility for the agency's capitulation with Richard Helms, the director of the CIA. He believed that "it was a political problem ... [Helms] didn't want the agency ... contravening the policy interest of the administration."

North Vietnam

Party politics

Planning in Hanoi for a winter-spring offensive during 1968 had begun in early 1967 and continued until early the following year. According to American sources, there has been an extreme reluctance among Vietnamese historians to discuss the decision-making process that led to the general offensive and uprising, even decades after the event. In official Vietnamese literature, the decision to launch the Tet offensive is usually presented as the result of a perceived U.S. failure to win the war quickly, the failure of the American bombing campaign against North Vietnam, and the anti-war sentiment that pervaded the population of the U.S. The decision to launch the general offensive, however, was much more complicated.

The decision signaled the end of a bitter, decade-long debate within the North Vietnamese Government between two, and later three, factions. The moderates believed that the economic viability of North Vietnam should come before support of a massive, conventional southern war and they generally followed the Soviet line of peaceful coexistence by reunifying Vietnam through political means. Heading this faction were party theorist Trường Chinh and Minister of Defense Võ Nguyên Giáp. The militant faction, on the other hand, tended to follow the foreign policy line of the People's Republic of China and called for the reunification of the nation by military means and that no negotiations should be undertaken with the Americans. This group was led by Communist Party First Secretary Lê Duẩn and Lê Đức Thọ (no relation). From the early to mid-1960s, the militants had dictated the direction of the war in South Vietnam. General Nguyễn Chí Thanh, the head of Central Office for South Vietnam (COSVN), headquarters for the South, was another prominent militant. The followers of the Chinese line centered their strategy against the U.S. and its allies on large-scale, main force actions rather than the protracted guerrilla war espoused by Mao Zedong.

By 1966–1967, however, after suffering massive casualties, stalemate on the battlefield, and destruction of the northern economy by U.S. aerial bombing, there was a dawning realization that if current trends continued, Hanoi would eventually lack the resources necessary to affect the military situation in the South. As a result, there were more strident calls by the moderates for negotiations and a revision of strategy. They felt a return to guerrilla tactics was more appropriate since the U.S. could not be defeated conventionally. They also complained that the policy of rejecting negotiations was in error. The Americans could only be worn down in a war of wills during a period of "fighting while talking". During 1967 things had become so bad on the battlefield that Lê Duẩn ordered Thanh to incorporate aspects of protracted guerrilla warfare into his strategy.

General offensive and uprising

The operational plan for the general offensive and uprising originated as the "COSVN proposal" at Thanh's southern headquarters in April 1967 and was relayed to Hanoi the following month. Thanh was then ordered to the capital to explain his concept in person to the Military Central Commission. At a meeting in July, Thanh briefed the plan to the Politburo. On the evening of 6 July, after receiving permission to begin preparations for the offensive, Thanh attended a party and died of a heart attack after drinking too much. An alternative account is that Thanh died of injuries sustained in a U.S. bombing raid on COSVN after having been evacuated from Cambodia.

After cementing their position during the Party crackdown, the militants sped up planning for a major conventional offensive to break the military deadlock. They concluded the Saigon government and the U.S. presence were so unpopular with the population of the South that a broad-based attack would spark a spontaneous uprising of the population, which, if the offensive was successful, would enable the North Vietnamese to sweep to a quick, decisive victory. Their basis for this conclusion included: a belief that the South Vietnamese military was no longer combat-effective; the results of the 1967 presidential election (in which the Thiệu/Kỳ ticket had only received 24 percent of the popular vote); the Buddhist crises of 1963 and 1966; well-publicized anti-war demonstrations in Saigon; and continuous criticism of the Thiệu government in the southern press. Launching such an offensive would also put an end to what had been described as "dovish calls for talks, criticism of military strategy, Chinese diatribes of Soviet perfidy, and Soviet pressure to negotiate—all of which needed to be silenced."

In October, the Politburo decided on the Tet holiday as the launch date and met again in December to reaffirm its decision and formalize it at the 14th Plenary session of the Party Central Committee in January 1968. The resulting Resolution 14 was a major blow to domestic opposition and "foreign obstruction". Concessions had been made to the center group, however, by agreeing negotiations were possible, but the document essentially focused on the creation of "a spontaneous uprising in order to win a decisive victory in the shortest time possible."

Contrary to Western belief, Giáp did not plan or command the offensive himself. Thanh's original plan was elaborated on by a party committee headed by Thanh's deputy, Phạm Hùng, and then modified by Giáp. The Defense Minister may have been convinced to toe the line by the arrest and imprisonment of most of the members of his staff during the Revisionist Anti-Communist Party Affair. Although Giáp went to work "reluctantly, under duress", he may have found the task easier due to the fact he was faced with a fait accompli. Since the Politburo had already approved the offensive, all he had to do was make it work. He combined guerrilla operations into a conventional military offensive and shifted the burden of sparking the popular uprising to the VC. If it worked, all would be well and good. If it failed, it would be a failure only for the Communist Party militants. For the moderates and centrists, it offered the prospect of negotiations and a possible end to the American bombing of the North. Only in the eyes of the militants did the offensive become a "go for broke" effort. Others in the Politburo were willing to settle for a much less ambitious "victory".

U.S. unpreparedness

Suspicions and diversions

Signs of impending communist action were noticed by allied intelligence organizations in Saigon. During the late summer and fall of 1967 both South Vietnamese and U.S. intelligence agencies collected clues that indicated a significant shift in communist strategic planning. By mid-December, mounting evidence convinced many in Washington and Saigon something big was underway. During the last three months of the year intelligence agencies had detected signs of a major North Vietnamese military buildup. In addition to captured documents (a copy of Resolution 13, for example, was captured by early October), observations of enemy logistical operations were also quite clear: in October, the number of trucks observed heading south through Laos on the Ho Chi Minh trail jumped from the previous monthly average of 480 to 1,116. By November this total reached 3,823 and, in December, 6,315. On 20 December, Westmoreland cabled Washington that he expected the PAVN/VC "to undertake an intensified countrywide effort, perhaps a maximum effort, over a relatively short period of time."

Despite all the warning signs, however, the allies were still surprised by the scale and scope of the offensive. According to ARVN Colonel Hoang Ngoc Lung the reason was allied intelligence methodology itself, which tended to estimate the enemy's probable course of action based upon their capabilities, not their intentions. Since, in the allied estimation, the communists hardly had the capability to launch such an ambitious enterprise: "There was little possibility that the enemy could initiate a general offensive, regardless of his intentions." The answer could also be partially explained by the lack of coordination and cooperation between competing intelligence branches, both South Vietnamese and American. The situation from the U.S. perspective was summed up by an MACV intelligence analyst: "If we'd gotten the whole battle plan, it wouldn't have been believed. It wouldn't have been credible to us." The Tet offensive would later be used in a textbook at West Point as an example of "an allied intelligence failure to rank with Pearl Harbor in 1941 or the Ardennes offensive in 1944." Lieutenant Colonel Dave R. Palmer: Current Readings in Military History.

From early to late 1967, the U.S. command in Saigon was perplexed by a series of attacks initiated by the PAVN/VC in the border regions. On 24 April a U.S. Marine Corps patrol prematurely triggered a PAVN offensive aimed at taking Khe Sanh Combat Base, the western anchor of the Marines' defensive positions in Quảng Trị Province. For 49 days during early September and lasting into October, the PAVN began shelling the U.S. Marine outpost of Con Thien, just south of the Demilitarized Zone (DMZ). The intense shelling (100–150 rounds per day) prompted Westmoreland to launch Operation Neutralize, an intense aerial bombardment campaign of 4,000 sorties into and just north of the DMZ.

Before the offensive

By the beginning of January 1968, the U.S. had 331,098 Army personnel and 78,013 Marines in nine divisions, an armored cavalry regiment, and two separate brigades in South Vietnam. They were joined there by the 1st Australian Task Force, a Royal Thai Army regiment, two Republic of Korea Army infantry divisions, and the Republic of Korea Marine Corps brigade. South Vietnamese strength totaled 350,000 regulars in the Army, Air Force, Navy and Marine Corps. They were in turn supported by the 151,000-man South Vietnamese Regional Forces and 149,000-man South Vietnamese Popular Forces, which were the equivalent of regional and local militias.

In the days immediately preceding the offensive, the preparedness of allied forces was relatively relaxed. Hanoi had announced in October it would observe a seven-day truce from 27 January to 3 February for the Tet holiday, and the South Vietnamese military made plans to allow leave for approximately half of its forces. General Westmoreland, who had already cancelled the truce in I Corps, requested that South Vietnam cancel the upcoming cease-fire, but President Thiệu (who had already reduced the cease-fire to 36 hours), refused to do so, claiming it would damage troop morale and only benefit communist propagandists.

On 28 January, eleven VC cadres were captured in the city of Qui Nhơn carrying two pre-recorded audio tapes whose message appealed to the populace in "already occupied Saigon, Huế, and Da Nang". The following afternoon, General Cao Văn Viên, chief of the South Vietnamese Joint General Staff, ordered his four Corps commanders to place their troops on alert. There was still a lack of a sense of urgency on the part of the allies. If Westmoreland had a grasp of the potential danger, he did not communicate it clearly others. On the evening of 30 January, 200 U.S. officers—all of whom served on the MACV intelligence staff—attended a pool party at their quarters in Saigon. According to James Meecham, an analyst at the Combined Intelligence Center who attended the party: "I had no conception Tet was coming, absolutely zero ... Of the 200-odd officers present, not one I talked to knew Tet was coming, without exception."

Westmoreland also failed to communicate his concerns adequately to Washington. Although he had warned the President between 25 and 30 January that "widespread" communist attacks were in the offing, his admonitions were so oblique or so hedged with official optimism that even the administration was unprepared. No one—in either Washington or Vietnam—was expecting what happened.

Offensive

"Crack the Sky, Shake the Earth"

The first wave of attacks began shortly after midnight on 30 January as five provincial capitals in II Corps and Da Nang, in I Corps, were attacked. Nha Trang, headquarters of the U.S. I Field Force, was the first to be hit, followed shortly by Buôn Ma Thuột, Kon Tum, Hội An, Tuy Hòa, Da Nang, Qui Nhơn, and Pleiku. Typically these were battalion or multi-battalion attacks, sometimes preceded by mortar or rocket bombardments.

The operations, however, were not well coordinated at the local level. By daylight almost all communist forces had been repelled from their objectives. In Nha Trang, 377 Vietcong had been killed and another 77 captured, while the ARVN garrison had lost 88 killed and another 32 civilian fatalities. General Phillip B. Davidson, the new MACV chief of intelligence, notified Westmoreland that "This is going to happen in the rest of the country tonight and tomorrow morning." All U.S. forces were placed on maximum alert and similar orders were issued to all ARVN units. The allies, however, still responded without any real sense of urgency. Orders cancelling leaves either came too late or were disregarded.

At 03:00 on 31 January PAVN/VC forces attacked Saigon, Cholon, and Gia Định in the Capital Military District; Quảng Trị city, Huế, Tam Kỳ and Quảng Ngãi as well as U.S. bases at Phú Bài and Chu Lai in I Corps; Phan Thiết, Tuy Hòa and U.S. installations at Bong Son and An Khê in II Corps; and Cần Thơ and Vĩnh Long in IV Corps. The following day, Biên Hòa, Long Thanh, Bình Dương in III Corps and Kien Hoa, Dinh Tuong, Gò Công, Kiên Giang, Vĩnh Bình, Bến Tre, and Kien Tuong in IV Corps were assaulted. The last attack of the first phase was launched against Bạc Liêu in IV Corps on 10 February. A total of approximately 84,000 PAVN/VC troops participated in the attacks while thousands more remained uncommitted to act as reinforcements or as blocking forces. Palmer gave a figure of 70,000. PAVN/VC forces also mortared or rocketed every major allied airfield and attacked 64 district capitals and scores of smaller towns.

In most cases the defense was led by the South Vietnamese. Local militia or ARVN forces, supported by the South Vietnamese National Police, usually drove the attackers out within two or three days, sometimes within hours; but heavy fighting continued several days longer in Kon Tum, Buôn Ma Thuột, Phan Thiết, Cần Thơ, and Bến Tre. The outcome in each instance was usually dictated by the ability of local commanders—some were outstanding, others were cowardly or incompetent. During this crucial crisis, however, no South Vietnamese unit broke or defected to the communists.

Saigon

Although Saigon was the focal point of the offensive, the PAVN/VC did not seek a total takeover of the city. Rather, they had six primary targets to strike in the downtown area: the headquarters of the ARVN Joint General Staff, Tan Son Nhut Air Base, the Independence Palace, the US Embassy in Saigon, the Republic of Vietnam Navy Headquarters and Radio Saigon. Elsewhere in the city or its outskirts, ten VC Local Force Battalions attacked the central police station and the Artillery Command and the Armored Command headquarters (both at Gò Vấp). The plan called for all these initial forces to capture and hold their positions for 48 hours, by which time reinforcements were to have arrived to relieve them.

The defense of the Capital Military District was primarily a South Vietnamese responsibility initially conducted by eight ARVN infantry battalions and the local police force. By 3 February they had been reinforced by five ARVN Ranger, five Marine Corps, and five ARVN Airborne battalions. U.S. Army units taking part in the defense included the 716th Military Police Battalion, seven infantry battalions (one mechanized), and six artillery battalions.

At the Armored Command and Artillery Command headquarters on the northern edge of the city, the initial PAVN plan called for the use of tanks and artillery pieces they hoped to capture in the initial assault. Their planners had not known the tanks had been moved to another base two months earlier and the breechblocks of the artillery pieces had been removed, rendering them useless.

One of the most important symbolic and propagandistic targets in the city was Radio Saigon. PAVN troops had brought along a tape recording of Hồ Chi Minh announcing the liberation of Saigon and calling for a "General Uprising" against the Thiệu government. They seized the building, held it for six hours and, running out of ammunition, the last eight attackers destroyed it and killed themselves using explosive charges. They were unable to broadcast due to the cutting of the audio lines from the main studio to the tower as soon as the station was seized.

The US Embassy in Saigon, a massive six-floor building situated within a four-acre compound, was attacked at 02:45 by a 19-man sapper team that gained entry by blowing a hole in the 8-foot-high (2.4 m) surrounding wall. Their officers were killed in the initial attack and when their attempt to gain access to the building failed the sappers occupied the chancery grounds. By 09:20 the compound was secured by U.S. reinforcements, with the loss of five U.S. personnel.

Huế

At 03:40 on the morning of 31 January, allied defensive positions north of the Hương River in the city of Huế were mortared and rocketed and then attacked by VC formations accompanied by two battalions of the PAVN 6th Regiment. Their target was the ARVN 1st Division headquarters located in the Citadel, a three-square mile complex of palaces, parks, and residences, surrounded by a moat and a massive earth and masonry fortress. The undermanned ARVN defenders, led by General Ngô Quang Trưởng, managed to hold their position, but the majority of the Citadel fell to the PAVN. On the south bank of the river, the PAVN 4th Regiment attempted to seize the local MACV headquarters, but was held at bay by a makeshift force of approximately 200 Americans. The rest of the city was overrun by PAVN forces that initially totaled approximately 7,500 men. Both sides then rushed to reinforce and resupply their forces. Lasting 25 days, the battle of Huế became one of the longest and bloodiest single battles of the Vietnam War.

During the first days of the North Vietnamese occupation, U.S. intelligence vastly underestimated the number of PAVN troops involved. Westmoreland informed the Joint Chiefs that "the enemy has approximately three companies in the Huế Citadel and the marines have sent a battalion into the area to clear them out." A later assessment ultimately noted three Marine and 11 Vietnamese battalions engaged at least 8 PAVN/VC battalions of the PAVN 6th Regiment, not including the large number of forces outside the city.

There were no U.S. formations stationed in Huế, amd relief forces had to move up from Phu Bai Combat Base, eight kilometers to the southeast. In a misty drizzle, U.S. Marines of the 1st Marine Division and soldiers of the 1st ARVN Division and Marine Corps cleared the city street by street and house by house, a deadly and destructive form of urban combat the U.S. military had not engaged in since the Battle of Seoul during the Korean War, and for which neither side was trained. Because of poor weather conditions, logistics problems and the historical and cultural significance of the city, American forces did not immediately apply air and artillery strikes as widely as they had in other cities.

VC forces around Huế included six main-force battalions, and two PAVN regiments operated in the area. As the battle unfolded three more PAVN regiments shifted from Khe Sanh arrived as reinforcements. The North Vietnamese plan of attack on Huế involved intensive preparation and reconnaissance. Over 190 targets, including every government and military installation on both sides of the river would be hit on January 31 by a force of five thousand. Other forces would block American and ARVN reinforcement routes, mainly Highway 1. Over half of the ARVN 1st Division was on holiday leave and PAVN commanders believed the population of Huế would join the fight as a part of the General Uprising.

Khe Sanh

The attack on Khe Sanh, which began on 21 January, probably served two purposes—as a real attempt to seize the position or as a diversion to draw American attention and forces away from the population centers in the lowlands, a deception that was "both plausible and easy to orchestrate." In Westmoreland's view, the purpose of the base was to provoke the North Vietnamese into a focused and prolonged confrontation in a confined geographic area, one that would allow the application of massive U.S. artillery and air strikes that would inflict heavy casualties in a relatively unpopulated region. By the end of 1967, MACV had moved nearly half of its manoeuvre battalions to I Corps in anticipation of just such a battle.

Westmoreland—and the American media, which covered the action extensively—often made inevitable comparisons between the actions at Khe Sanh and the Battle of Điện Biên Phủ, where a French base had been besieged and ultimately overrun by Viet Minh forces under the command of General Giáp during the First Indochina War. Westmoreland, who knew of Nguyen Chi Thanh's penchant for large-scale operations—but not of his death—believed this was going to be an attempt to replicate that victory. He intended to stage his own "Dien Bien Phu in reverse."

Khe Sanh and its 6,000 U.S. Marine Corps, Army and ARVN defenders was surrounded by two to three PAVN divisions, totaling approximately 20,000 men. Throughout the siege, which lasted until 8 April, the allies were subjected to heavy mortar, rocket, and artillery bombardment, combined with sporadic small-scale infantry attacks on outlying positions. With the exception of the overrunning of the U.S. Special Forces camp at Lang Vei, there was never a major ground assault on the base and the battle became largely a duel between American and North Vietnamese artillery, supplemented with massive air strikes conducted by U.S. aircraft. By the end of the siege, U.S. Air Force, Marine Corps, and Navy aircraft had dropped 39,179 tons of ordnance in the defense of the base.

In the end, a major allied relief expedition (Operation Pegasus) launched by all three brigades of the 1st Cavalry Division reached Khe Sanh on 8 April, but PAVN forces were already withdrawing from the area. Both sides claimed the battle had served its intended purpose. MACV estimated that 5,500 PAVN troops had been killed and considerably more wounded. During the entire battle from 1 November 1967 to 14 April 1968, 730 U.S. personnel were killed and another 2,642 wounded. Khe Sanh Base was later closed on 5 July 1968 because the base was seen as having less of a strategic importance than before.

Aftermath

Except in Huế and mopping-up operations in and around Saigon, the first surge of the offensive was over by the second week of February. The U.S. estimated during the first phase (30 January – 8 April) approximately 45,000 PAVN/VC soldiers were killed and an unknown number were wounded. For years this figure has been held as excessively optimistic, as it represented more than half the forces involved in this battle. Westmoreland himself claimed a smaller number of enemies disabled, estimating that during the same period 32,000 PAVN troops were killed and another 5,800 captured. According to Max Hastings, the Tet Offensive, including the following "Mini-Tet" offensives in May and August of 1968, resulted in the deaths of 50,000 VC (total casualties drained 60-70% of their strength), while US forces lost 4,000 killed and ARVN 6,000 dead.

The South Vietnamese suffered 2,788 killed, 8,299 wounded, and 587 missing in action. U.S. and other allied forces suffered 1,536 killed, 7,764 wounded, and 11 missing.

According to the best estimates by MACV intelligence officers, the combined Viet Cong and PAVN forces in South Vietnam numbered 262,000 at the end of 1967. Expansion of the forces in preparation for the Tet Offensive increased the figure to 287,000 by the end of January 1968. Both Viet Cong and PAVN forces suffered heavy losses during the following months. They were able to find replacements for some but not all of the losses, and at the end of 1968, the Viet Cong and PAVN forces had an estimated strength of 251,000.

North Vietnam

The leadership in Hanoi was disappointed with the outcome of the offensive. Their first and most ambitious goal, producing a general uprising, was a failure. In total, about 85,000–100,000 PAVN/VC troops had participated in the initial offensive and in the follow-up phases.

According to historian James Willbanks, Hanoi underestimated the strategic mobility of the allied forces. This mobility allowed them to redeploy at will to threatened areas. The battle plan was also too complex and difficult to coordinate, which was amply demonstrated by the 30 January attacks. Hanoi's plan also violated the military principle of mass - attacking everywhere instead of concentrating their forces on a few specific targets - allowing their forces to be defeated piecemeal. When they did use mass, PAVN/VC forces launched attacks directly towards an enemy with vastly superior firepower. According to Trần Văn Trà: "We did not correctly evaluate the specific balance of forces between ourselves and the enemy, did not fully realize that the enemy still had considerable capabilities, and that our capabilities were limited, and set requirements that were beyond our actual strength."

The PAVN/VC effort to regain control of the countryside was somewhat more successful. According to the U.S. State Department, the VC "made pacification virtually inoperative. In the Mekong Delta, the Viet Cong was stronger now than ever and in other regions the countryside belongs to the VC." General Earle Wheeler reported that the offensive had brought counterinsurgency programs to a halt and "that to a large extent, the VC now controlled the countryside". This state of affairs did not last; heavy casualties and military operations of the South Vietnamese and Americans resulted in more territorial losses and heavy casualties.

One historian claims heavy losses inflicted on VC units struck into the heart of the infrastructure that had been built up for over a decade, claiming that 181,149 PAVN/VC troops had been killed during 1968.

Marilyn B. Young writes:

In Long An province, for example, local guerrillas taking part in the May—June offensive had been divided into several sections. Only 775 out of 2,018 in one section survived; another lost all but 640 out of 1,430. The province itself was subjected to what one historian has called a "My Lai from the Sky"—non-stop B-52 bombing.

South Vietnam

South Vietnam was in turmoil both during and in the aftermath of the offensive, as the conflict reached into cities for the first time. As government troops pulled back to defend urban areas, the VC moved in to fill the vacuum in the countryside. The violence and destruction witnessed during the offensive left a psychological scar on the South Vietnamese civilian population, as confidence in the government was shaken, since the offensive seemed to reveal that, even with massive American support, the government could not protect its citizens in urban areas.

A political rivalry had also re-emerged after the 1967 South Vietnamese presidential election, when the coalition between Nguyễn Văn Thiệu, and former Air Force commander and Vice President Nguyễn Cao Kỳ re-emerged. Kỳ would be sidelined by Thiệu for the duration of the war afterwards, retaining his position as Vice President.

The human and material cost to South Vietnam was significant. The number of civilian dead was estimated by the government at 14,300 with an additional 24,000 wounded. Around 630,000 new refugees had been displaced, joining the nearly 800,000 others already displaced by the war. By the end of 1968, one of every twelve South Vietnamese was living in a refugee camp. More than 70,000 homes had been destroyed in the fighting and perhaps 30,000 more were heavily damaged and the nation's infrastructure had been virtually destroyed. The South Vietnamese military, although it had performed better than the Americans had expected, suffered from lowered morale, with desertion rates rising from 10.5 per thousand before Tet to 16.5 per thousand by July. 1968 became the deadliest year of the war to date for the ARVN with 27,915 men killed.

In the wake of the offensive, however, fresh determination was exhibited by the Thiệu government. On 1 February Thiệu declared a state of martial law, and on 15 June the National Assembly passed his request for a general mobilization of the population and the induction of 200,000 draftees into the armed forces by the end of the year (a decree that had failed to pass only five months previously). This would bring South Vietnam's troop strength to more than 900,000 men. Military mobilization, anti-corruption campaigns, demonstrations of political unity, and administrative reforms were quickly carried out. Thiệu also established a National Recovery Committee to oversee food distribution, resettlement, and housing construction for the new refugees. Both the government and the Americans were encouraged by a new determination exhibited by the ordinary citizens of South Vietnam. Many urban dwellers were indignant that the communists had launched their attacks during Tet, and it drove many who had been previously apathetic into active support of the government. Journalists, political figures, and religious leaders alike—even the militant Buddhists—professed confidence in the government's plans.

United States

The Tet Offensive created a crisis within the Johnson administration, which became increasingly unable to convince the American public that it had been a major defeat for the communists. The optimistic assessments made before the offensive by the administration and the Pentagon came under heavy criticism and ridicule as the "credibility gap" that had opened in 1967 widened into a chasm.

At the time of the Tet Offensive, the majority of the American public felt the war was not being won by the United States and its allies, despite assurances from the President and military leaders to the contrary. Even if the PAVN/VC lost about 30,000 of their best troops in the fighting at Tet, they were capable of making up the losses with replacements from North Vietnam. In 1969, the year after the Tet battles, the US suffered 11,780 killed, the second highest annual total in the war. This was a clear indication that the North Vietnamese were capable of ongoing offensive actions, despite their losses at Tet. Most Americans were tired of suffering so many casualties without evidence they were going to stop anytime in the foreseeable future. Walter Cronkite, anchorman of the CBS Evening News, argued for negotiations as an honorable way out in a Special Report based on his journalism in Vietnam broadcast on CBS TV in March.

The shocks that reverberated from the battlefield continued to widen: On 18 February 1968 MACV posted the highest U.S. casualty figures for a single week during the entire war: 543 killed and 2,547 wounded. As a result of the heavy fighting, 1968 went on to become the deadliest year of the war for the US forces with 16,592 soldiers killed. On 23 February the U.S. Selective Service System announced a new draft call for 48,000 men, the second highest of the war. On 28 February Robert S. McNamara, the Secretary of Defense who had overseen the escalation of the war in 1964–1965, but who had eventually turned against it, stepped down from office.

During the first two weeks of February, Generals Westmoreland and Wheeler exchanged messages regarding the necessity for reinforcements or troop increases in Vietnam. Westmoreland insisted he only needed those forces either in-country or already scheduled for deployment and he was puzzled by the sense of unwarranted urgency in Wheeler's queries. Westmoreland was tempted, however, when Wheeler emphasized that the White House might loosen restraints and allow operations in Laos, Cambodia, or possibly even North Vietnam itself. On 8 February, Westmoreland responded he could use another division "if operations in Laos are authorized". Wheeler responded by challenging Westmoreland's assessment of the situation, pointing out dangers that his on-the-spot commander did not consider palpable, concluding: "In summary, if you need more troops, ask for them."

Phase II

To further enhance their political position at the Paris talks, which opened on 13 May, the North Vietnamese opened the second phase of the general offensive in late April. U.S. intelligence sources estimated between February and May the North Vietnamese moved 50,000 men down the Ho Chi Minh trail to replace losses incurred during the earlier fighting. Some of the most prolonged and vicious combat of the war opened on 29 April and lasted until 30 May when the 8,000 men of the PAVN 320th Division, backed by artillery from across the DMZ, threatened the U.S. logistical base at Đông Hà, in northwestern Quảng Trị Province. In what became known as the Battle of Dai Do, the PAVN clashed savagely with U.S. Marine, Army and ARVN forces before withdrawing. The PAVN lost an estimated 2,100 men according to US/ARVN claims, after inflicting casualties on the allies of 290 killed and 946 wounded.

During the early morning hours of 4 May, PAVN/VC units initiated the second phase of the offensive (known by the South Vietnamese and Americans as "Mini-Tet") by striking 119 targets throughout South Vietnam. This time, however, allied intelligence was better prepared, stripping away the element of surprise. Most of the communist forces were intercepted by allied screening elements before they reached their targets. 13 VC battalions, however, managed to slip through the cordon and once again plunged the capital into chaos. Severe fighting occurred at Phu Lam, (where it took two days to root out the VC 267th Local Force Battalion), around the Y-Bridge and at Tan Son Nhut. By 12 May, however, it was all over. VC forces withdrew from the area leaving behind over 3,000 dead.

The fighting had no sooner died down around Saigon than U.S. forces in Quảng Tín Province suffered a defeat when the PAVN 2nd Division attacked Kham Duc, the last Special Forces border surveillance camp in I Corps. 1,800 U.S. and ARVN troops were isolated and under intense attack when MACV made the decision to avoid a situation reminiscent of that at Khe Sanh. Kham Duc was evacuated by air while under fire and abandoned to the North Vietnamese.

The PAVN/VC returned to Saigon on 25 May and launched a second wave of attacks on the city. The fighting during this phase differed from Tet Mau Than and "Mini-Tet" as no U.S. installations were attacked. Instead, VC forces occupied six Buddhist pagodas in the mistaken belief they would be immune from artillery and air attack. The fiercest fighting once again took place in Cholon. One notable event occurred on 18 June when 152 members of the VC Quyet Thang Regiment surrendered to ARVN forces, the largest communist surrender of the war. The attacks also brought more death and suffering to the city's inhabitants. A further 87,000 were made homeless while more than 500 were killed and another 4,500 were wounded. During part of the second phase (5 May – 30 May) U.S. casualties amounted to 1,161 killed and 3,954 wounded,

Phase III

Phase III of the offensive began on 17 August and involved attacks in I, II and III Corps. During this phase only North Vietnamese forces participated and targets were mostly military in nature. The main offensive was preceded by attacks on the border towns of Tây Ninh, An Lộc, and Loc Ninh, which were again intended to draw defensive forces from the cities. A thrust against Da Nang was preempted by the U.S. Marines' Operation Allen Brook. Continuing their border-clearing operations, three PAVN regiments asserted heavy pressure on the U.S. Special Forces camp at Bu Prang, in Quang Duc Province, five kilometers from the Cambodian border. The fighting lasted for two days before the PAVN broke contact; the combat resulted in US/ARVN claiming 776 PAVN/VC casualties, 114 South Vietnamese and two Americans.

Saigon was struck again during this phase, but the attacks were less sustained and once again repulsed. As far as MACV was concerned, the August offensive "was a dismal failure". In five weeks of fighting and after the loss of 20,000 troops, the previous objectives of spurring an uprising and mass-defection had not been attained during this "final and decisive phase". However, as argued by the historian Ronald H. Spector, "the communist failures were not final or decisive either".

The significant casualties and suffering endured by PAVN/VC units during these sustained operations were beginning to have a wider effect. The apparent lack of military gains that might have justified the casualties and effort exacerbated the situation. During the first half of 1969, more than 20,000 PAVN/VC troops defected to allied forces, a threefold increase over the 1968 figure.