- NLF guerrilla fighters
Build-up to the offensive: 1965-8
The decision that the US would make a stand in Vietnam and not permit a Communist victory was taken not by Johnson, but as early as 1962 by John F Kennedy. Shocked by events like the evolution of the Cuban revolution, the development of of leftist nationalism in the Congo and elsewhere and a series of guerrilla struggles in the Portuguese colonies , the American political and intelligence elites began to worry that ‘Moscow’, ‘Beijing’ or ‘the Communists’ more generally were evolving a strategy of armed national liberation struggles in the third world.
The main danger of ‘Communist aggression’ shifted from an entirely mythical prospect of a Soviet invasion of Western Europe to the very real danger of guerrilla uprisings in Asia, Africa and Latin America. In his inaurgural address Kennedy said the US would “pay any price, bear any burden, meet any hardship, support any friend, oppose any foe, in order to assure the survival and success of liberty”. What this meant, and who exactly would be required to "pay any price" became very clear in Vietnam.
By 1965 there were half a million American soldiers in Vietnam. It was not until US forces had reached this figure that PAVN units were detected in South Vietnam; before that the fighting was done mainly by the part-time guerrillas of the NLF. American strategy revolved around two tactics:
1) An attempt to punish North Vietnamese support for the NLF by destroying the infrastructure of North Vietnam in aerial bombing (Operation ‘Rolling Thunder’).
2) ‘Search and destroy’ missions in the Vietnamese countryside, punishing the Vietnamese peasants for their support of the NLF by destroying hundreds of villages, and trying to force the NLF and PAVN into open battle. The key objective was to inflict maximum casualties in a war of attrition.
Rolling Thunder in its three years of permanent bombing achieved its objective of destroying most of North Vietnam’s infrastructure. By the time Johnson suspended the bombing of the North, US air planners were having difficulties finding targets still standing to bomb. Paradoxically, Rolling Thunder saw one of the most effective anti-aircraft efforts in history. More than 1200 American planes were shot down, including dozens of giant B52 bombers and hundreds of fighter-bombers. Around one thousand US air crew were killed and hundreds taken prisoner. It seems likely that China supplied some anti-aircraft units in the early phase of the campaign, but the decisive surface-to-air missiles were supplied by the Soviet Union. Some US planes were shot down in dogfights with Vietnamese airforce MiGs, but the accusation that some of these planes were flown by Russian pilots is unproven.
Despite the success of the anti-aircraft effort – extraordinary by the standards of the two anti-Iraq wars – the scale of the bombing campaign made it unstoppable. Tens of thousands of North Vietnamese civilians died. Michael Maclear, a Canadian journalist who visited North Vietnam during Rolling Thunder, estimates the number of civilian dead at 180,000 . He says, "The journey showed that five cities had been levelled. These, traveling south, were the cities of Phu Ly, Ninh Binh, Thanh Hoa, Vinh and Ha Tinh, each formerly with populations between 10,000 and 30,000. The North’s third largest city, Nam Dinh - population 90,000 -was largely destroyed but at least recognizable. Another 18 destroyed centers were classified as towns" . But it did not prevent or even seriously interrupt the supply of soldiers and materials southwards via the Ho Chi Minh trail through Cambodia.
America’s attrition strategy in the South smashed the social structure of the Vietnamese countryside and killed up to a million people in the countryside  – most of them civilians While not crushing the insurgency, the war on the peasantry made it much more difficult. The US outdid the colonial savagery exhibited by the British in Malaya and the French in Algeria in its ruthless and systematic massacre of peasant villagers. Many were herded into ‘strategic hamlets’ on the Malayan model; but after this strategy failed, hundreds of thousands fled the bombing and streamed into the relative safety of the major cities which became bloated with refugees .
- Supplies coming down the Ho Chi Minh trail
Between 1965 and 1967 dozens of battles were fought by US soldiers and marines against the NLF and PAVN. Despite escalating claims of military success in the daily ‘body count’, the US commanders were unable to inflict any crushing defeats on the Vietnamese. In this period the anti-war movement grew worldwide – and decisively in the United States – as news of the savagery of the war filtered through and the toll of US dead grew.
Response of the Vietnamese Communist leadership
It’s now clear that a debate broke out inside the Communist Party (VCP) in 1967 about how to confront this situation of stalemate, where the prodigious use of heavy artillery and aerial bombardment, together with highly mobile helicopter transported troops, was both depopulating the countryside and making insurgent victories difficult.
Some writers have attempted to assign different hard-and-fast positions to particular VCP leaders, claiming that Le Duan led the ‘militants’ who eventually won a struggle in favour of a general uprising against those who wanted a ‘protracted peoples war’ (drawn out guerrilla struggle) plus negotiations, or alternatively conventional warfare plus negotiations. Whatever the truth of the precise positions adopted by different VCP leaders, such a debate is entirely normal and indeed closely parallels debates in the Sandinista leadership before 1979 and the FMLN leadership during the Salvadorean insurgency.
- US military police battle to re-take the US embassy.
By mid-1967 the party leadership had embarked on a line of “General Offensive, General Uprising”. This would involve countrywide attacks on the US military, but also an invasion of the cities on a perspective of provoking an urban uprising against the Americans and their South Vietnamese Allies. Gabriel Kolko in his book Vietnam - Anatomy of War says that feelers were put out to non-Communist Vietnamese exiles about the possibility of forming a Provisional Government with the NLF in the event that the offensive scored a major success (which presumably would involve the capture of at least one provincial capital).
Gabriel Kolko argues that the Tet offensive was not launched on the perspective that a general uprising was certain, but only that it was possible. Rather, he argues, the VCP leadership hoped for an uprising but in any event felt the offensive would strike a decisive military blow to the Americans and South Vietnamese army from which they would never fully recover .
There’s a Storm Coming
From September 1967 NLF and PAVN commanders began to be briefed on the coming offensive. Articles in the Vietnamese press analysed the state of the war and military perspectives; according to observers these articles, read carefully, revealed the possibility of a general offensive. Vast amounts of matériel began to be moved southward and new PAVN units set off down the Ho Chi Minh trail. American intelligence, including documents captured in battle, revealed that a major offensive was planned, but the US military was confused about the scope and the timing. Nobody believed that the offensive, if there was one, would be on the scale that eventually happened.
PAVN commander Vo Nguyen Giap, the victor of Dien Bien Phu , planned a series of attacks in the border areas in October and November 1967 to draw the US and South Vietnamese troops away from the cities. At the same time the US base at Khe Sanh was besieged by the PAVN, and remained invested until April 1968, resulting in hundreds of US dead. American planners wondered whether these battles were the offensive; they weren’t, and when the real offensive came it was a complete shock.
The attack unrolled on January 30 as six provincial capitals and many US bases came under attack. This first wave seems to have been an extraordinary mistake because of the use of different calendars by different PAVN and NLF battalions. Next night, 31 January, the real blow was dealt as hundreds of targets were attacked through South Vietnam. NLF fighters attacked key point in Saigon and invaded the US embassy. US military police had to fight a six-hour battle to regain control of the symbol of US power in the country. This caused a news sensation worldwide.
- Punishing the peasantry for supporting NLF
Most of the attacks however were thrown back, sometimes with heavy NLF and PAVN losses. However in the Saigon Chinese suburb Cholon the NLF fighters could not be shifted. This battle was televised and reverberated worldwide. The NLF were driven out only after a massive aerial bombardment which killed hundreds of civilians.
PAVN troops held the northern provincial capital Hue for 26 days, a battle that provoked the spectacularly inept comment b y a US commander that “we had to destroy the city to save it”. Indeed, with a huge toll in civilian lives. After the city was retaken by US troops, the Americans claimed that mass graves had been found in which the bodies of hundreds of civilians executed by the PAVN were deposited. Subsequent research has shown that after the city was retaken South Vietnamese ‘revenge squads’ executed anyone suspected of collaborating with the PAVN.
The attacks during Tet had been spectacular, but they had not given rise to a popular uprising. Why not? The civilians who flooded into the cities because of US bombing were in general outside the reach of NLF propaganda and agitation. In any case, it is incredibly hard for an urban population to ‘rise up’ against a well-armed and brutal enemy if it has no prior form of organisation, has no weapons and no way of physically defending itself, particularly if there is no sign of the insurgents scoring a decisive victory. That it also the lesson the attempted general uprising by the FMLN  in El Salvador in 1979; the insurgents lacked the means to defend the civilian population that they were asking to rise up.
More generally the offensive showed the difficulty of defeating huge armies that are very mobile  and have superior weaponry in head-on pitched battle. Knocking out the US and South Vietnamese armies was too big a target for a single blow. In any case, the whole history of national liberation guerrilla warfare from Algeria to Mozambique shows the colonial powers were driven out by a long and difficult guerrilla struggle (including a vital urban element in Algeria); they were worn down, demoralised, politically defeated in the long run.
Political axes of the insurgency
The political objectives of the insurgency were set out clearly in broadcasts by Hanoi Radio, Dai Giai Phong (Liberation Radio) and by numerous proclamations handed out in leaflets to the population. These announced the formation of a National, Democratic and Peace Alliance Front, putting the emphasis on the national and democratic tasks of the revolution. They also announced the formation of numerous united front committees, appealing particularly to professional people, religious groups, young people and others to join the uprising. Particular emphasis was put on calls to rank and file South Vietnam Army troops to desert. Also crucial were the announcement of Uprising Committees, effectively the NLF, to direct the military struggle.
On 31 January Hanoi radio’s domestic service quoted the Saigon Uprising Committee thus: "The Uprising Committee calls on all the people and the revolutionary forces in Saigon to resolutely stand up to and constantly attack the enemy and win complete victory. The Uprising Committee calls on the compatriots in the areas still under control of the Thieu-Ky-Loan clique’s temporary control to firmly and vigorously oppose terrorism, to help the revolutionary forces track down the dishonest and cruel lackeys, to form patriotic forces and patriotic neutralist forces, and to contribute to liberating our beloved city. The Uprising Committee also calls on the puppet troops of the general reserve forces and ranger and police forces and the armoured and artillery forces not to die uselessly for the country-selling and bloodthirsty Thieu-Ky-Loan clique, to fire on it, and to swiftly join the revolutionary ranks in scoring achievements for the fatherland." 
In Hue, as in many other places, the National, Democratic and Peace Alliance Front made a specific appeal for the people to rise up: "The National, Democratic and Peace Alliance Front urgently calls on all groups and all forces of patriotic people, youths, women, college students, and high school students in Hue city, to rise up to conduct an armed uprising, to overthrow the traitorous Thieu-Ky clique, to force the Americans to withdraw from the South, to wrest back the administration to the people, and to achieve peace and independence for the country. The fatherland and nation call on all people in Hue city to rise up as one man".
Numerous similar broadcasts and leaflets were monitored by US intelligence. They revealed at least the public objectives of the offensive - to create a broad front of all forces opposed the South Vietnamese regime and hostile to the American occupation, to overthrow the Thieu-Ky South Vietnamese government, to win over substantial sections of South Vietnamese troops, to form popular organisations for every major social sector and to unite these into a provisional government that would negotiate with the NLF about peace and national reunification. The violence of the US response, and its willingness to inflict huge civilian casualties to drive the NLF-PAVN out of towns and cities made these objectives unobtainable.
To the ‘losers’ the spoils
Anti-Communist commentators were not slow in proclaiming Tet to be an enormous defeat for the Communists. Walter Schwartz was given two pages in the London Guardian to prove that the military losses incurred by the insurgents were so huge that they had lost the war. But after Tet proclamations by American commanders suffered from what became known at the time as the ‘credibility gap’. General Westmorland had regularly briefed the world’s press on the major defeats suffered by the NLF and PAVN; such optimistic accounts excluded the possibility of such nationwide attacks. In particular US public opinion was utterly shocked, not only by the scale of the offensive but by the brutal scenes in Saigon shown on their television screens. The eventual withdrawal of US troops was made certain by this event.
For the Vietnamese Communists the outcome was both much more and much less than they expected. Military it was less successful than expected; one result seems to have been a disproportionate rate of casualties among the units of the NLF who, as the people with local knowledge, were the first to enter the cities. After Tet the NLF was never again so prominent in the fighting, which became increasingly a conventional war in which many North Vietnamese units used heavy artillery and tanks - not the weapons of guerrilla war.
- This picture of the execution of an NLF fighter shocked world opinion
Politically the offensive was successful beyond the wildest dreams of the VCP leadership. Not only was the Washington government confused and humiliated, a big boost was given to anti-war opinion worldwide.
More than that, the Tet offensive outcome was politically appropriated by the Left internationally, and formed an essential part of the backdrop, the political spirit of the times, which suffused the events in other countries later that year. The February 1968 Berlin international Vietnam conference and demonstration was held in the immediate wake of the offensive beneath a banner proclaiming “The duty of the revolutionary is to make the revolution”. Politically Tet showed the imperialists were not invincible; moreover those fighting them in Vietnam, unlike Iraq, were politically of the Left. Socialists of many types could sympathise with these fighters, even if they had criticisms of the VCP. Vietnam was also widely seen as a social revolution, not just a national liberation struggle. Tet was a further boost to the Left’s interpretation of the world and helped generate an atmosphere favourable to discussion to anti-imperialist and revolutionary socialist themes, especially amongst young people.
Richard Nixon took office in January 1969 and began negotiations in earnest, leading to the withdrawal of most American troops by 1973. From then on it was just a matter of time before the South Vietnamese government collapsed and the country was reunified, finally accomplished in May 1975.
British social commentator Will Hutton  claims that the real result of the Vietnam war was that the ability of the Americans to hold off the VCP until 1975 prevented a swathe of South East Asian states from succumbing to Communism. Like most counterfactual history, there is no way of proving that one way or another. Even it that were true, it was achieved at an enormous price. The United States’ ability to intervene elsewhere was stymied for a generation. Military deficit spending caused huge inflation in the world economy and the decline of the dollar, which in turn were major contributors to the 1975-5 world slump. The US was forced into a shockingly brutal imperialist war that transformed the words “US imperialism” from a leftist cliché into a vivid reality for hundreds of thousands. The war brought forth a mass anti-war movement within which the traditions of international solidarity were rebuilt after being largely absent since the Spanish civil war. And by no means least, it put the forces of revolutionary socialism in the imperialist countries to the fore in a mass movement for the first time since the 1930s.