30 January – 8 April 1968

A young girl soldier fighting for the North Vietnamese in the Cuu Long Delta prepares to fire an anti-tank gun during the Tet Offensive, which was launched in January 1968 against 105 towns and cities across South Vietnam. Though a failure militarily, the offensive stunned the American army stationed in Vietnam and brought North Vietnamese victory a step nearer.

In September 1967, General Vo Nguyen Giap, commander-in-chief of the communist North Vietnamese Army (NVA), announced a strategy to ‘directly hit the enemy in his deepest lair’. The enemy was the Military Assistance Command Vietnam, a force of almost half a million American men and women supporting the South Vietnamese government and the Army of the Republic of Vietnam (ARVN). Rather than engage in a single pitched battle on unequal terms, the North Vietnamese plan was to infiltrate the whole of South Vietnam and attack hundreds of government buildings and military bases simultaneously. For the strategy to work, absolute secrecy was required. The preparation for what became known as the Tet Offensive involved one of the largest and most complex deception plans ever mounted in warfare.

Secrecy was necessary because the North Vietnamese Army and the southern communists, or Viet Cong, were not only greatly outnumbered by American and ARVN forces, but possessed only a fraction of the sophisticated military equipment available to the enemy. The deception involved two approaches: first, it was necessary to persuade the Americans that the real threat came in the North, from NVA incursions across the demilitarized zone between North and South Vietnam; second, it was necessary to infiltrate thousands of soldiers and guerrilla fighters into the towns and cities of the South in order to build up reserves of equipment and ammunition and to dig numerous bunkers and tunnels concealed from the enemy. This was done without divulging the overall plan to those involved, or the date of the operations. Over the winter months an estimated 65–80,000 communist regular and irregular troops moved into position around South Vietnam. To make surprise more certain, the North Vietnamese decided to launch the offensive during the Tet New Year celebrations at the end of January when a period of truce traditionally existed between the two sides. A seven-day truce was agreed from 27 January to 3 February, during which it was assumed that the South Vietnamese armed forces would be on low alert. The assault on the towns would also make it more difficult for the Americans to deploy the tanks, aircraft and helicopter gunships that they used in open country.

On 20 January, the NVA began the active part of its deception by launching a surprise assault on the American Marine base at Khe Sanh, near the northern border of South Vietnam. The redoubts around the base were attacked using rockets, mortars and machine-gun fire. The base itself came under heavy fire and a 1,500-ton ammunition dump exploded. The runway was hit, leaving only a 600-metre (2,000-foot) strip still viable. Using trenches and bunkers dug almost up to the base perimeter, the NVA kept up a remorseless fire. Khe Sanh threatened to become another Dien Bien Phu.

Both deceptions worked up to a point. The Americans’ gaze was directed at Khe Sanh and their efforts went into reinforcing the threatened base. Although intelligence sources suggested that something was going to happen in the rest of South Vietnam, there was no clue as to when or how extensive the offensive might be. The Tet holiday was celebrated in North Vietnam a day early, a decision explained to the population by an apparently favourable configuration of the Earth and the Sun that day. In the South, soldiers began leaving for the annual celebrations, though a state of alert was finally ordered. The surprise was not total, but the scale of the offensive was quite unanticipated. In and around Saigon, the southern capital, two Viet Cong divisions and thirty-five NVA battalions had infiltrated, quite undetected.

In the end the deception was undone by the need for secrecy. The local units in the South did not understand the importance of co-ordination. The date for the attack was changed at the last moment from the night of 30 January to the night following, but some units failed to receive the instruction, and in the early hours of the morning of 30 January attacks began in twelve towns in the north of the country. The American commander, General William Westmoreland, still thought that this was a diversion to mask a greater assault planned across the demilitarized zone. Only when the following night showed communist attacks right across the country did the nature of the offensive become clear. The insurgents hit 5 out of 6 cities,36 out of 44 provincial capitals and 64 out of 245 district capitals. Using automatic weapons, rockets and mortar fire, government buildings and military bases were either bombarded or, once communist sappers had done the work of cutting the wire and removing mines, infiltrated by NVA and Viet Cong forces. Fierce firefights broke out across the country, though in many cases the attacks were halted and the insurgents killed or captured. The strong assault on Quang Tri was defeated in a day of fighting. Only in three towns did a major battle develop, with heavy casualties on both sides.

The longest battles took place in Da Nang, Hue and Saigon. Da Nang, headquarters of the US 1st Corps, was subjected to two weeks of intermittent attack, including the destruction of aircraft on the Da Nang airfield. The American forces suffered 681 casualties in the struggle, the communist forces 1,300. In Hue, the NVA succeeded in taking over and occupying the town citadel. Fighting in difficult conditions around the city, the US Marines assigned to the battle found conditions not unlike Stalingrad. When buildings were cleared of the enemy in the day, they were stealthily reoccupied again at night. Not until 2 March was the city again in South Vietnamese hands. In Saigon, the communists concentrated on the Chinese suburb of Cholon, though attacks were also made on the US Embassy and the presidential palace. The street fighting in Cholon lasted a month, though the rest of Saigon was secured in a few days. Across the South and the Mekong Delta, hundreds of incidents brought a countrywide series of skirmishes and ambushes, but nothing on the scale of the continued battle at Khe Sanh, which more closely resembled a conventional battlefield. Here major redoubts at Lang Vei Camp and Alpha 1 were overrun, with heavy American casualties. At Lang Vei, 300 of the 487 defenders were killed, wounded or missing. Reinforcements battled their way in, but the key effort was made to re-open Route 9, the main road to the base. ‘Operation Pegasus’ involved 30,000 troops, the largest single deployment of the war. On 8 April, the siege was lifted and the NVA retreated back to the North.

The Tet Offensive failed on a military level, leaving an estimated 32,000 communist dead. The communist purpose had been to use the offensive to spark a revolutionary uprising among the South Vietnamese population and this it failed to do. There was, however, one major political achievement: the deception shocked American military commanders and the American public and accelerated the winding-down of the American commitment in Vietnam. By 1972, the Americans had withdrawn altogether. World opinion understood that the American assurances given in late 1967 that the war was almost over were entirely misplaced. In this sense, Tet was a turning point in the communist struggle to create a single Vietnamese nation by attacking the ‘deepest lair’.