As a prelude to Tet, on 20 January 1968, nearly 40,000 North Vietnamese troops besieged the U.S. Marine base at Khe Sanh near the DMZ. U.S. Marines and Army troops, supported by air bombardment and artillery plus airborne supply, responded to mount a successful 77 day defense of Khe Sanh, finally broken on 6 April by the Army’s 1st Cavalry Division. While Khe Sanh ultimately resulted in the loss of about 10,000 NVA troops, it had the effect of drawing attention to the north and thinning out support near the South Vietnamese cities. This dovetailed with the plans of N. Vietnamese General Vo Nguyen Giap who sought a confrontation and "knockout blow" in the population centers of South Vietnam. Giap and other N. Vietnamese leaders believed that the population in S. Vietnam was ready to revolt and join the Communist cause, if given the opportunity. Optimistic American planners did not understand that Giap would pay any price in blood to achieve his objectives. Allied intelligence failed to recognize the changing enemy strategy.
In late January 1968, Vietnam prepared for the annual Tet (Lunar New Year) celebration. As in prior years, a cease fire was arranged with Communist forces (the North Vietnam Army (NVA) and the Viet Cong (VC)). Most South Vietnamese Army units (ARVN) were under strength as soldiers were granted leave to attend family events arranged for Tet, while American and allied units were at low alert, expecting a period of quiet.
ARVN troops during the Tet Offensive, 1968.
Early in the morning of 31 January 1968, more than 80,000 NVA and VC erupted from carefully infiltrated positions to attack six major cities, thirty six provincial capitals and twenty three airfields and military bases, almost every important location and target in South Vietnam. Major assaults were conducted on Saigon, Da Nang, Qui Nhon, Quang Tri, Kontum, Ban Me Thout, My Tho, Can Tho, Ban Tre and other places. At ten of these locations, the Communists temporarily wrested control from the ARVN and Americans holding them. In Saigon, where 4,000 Viet Cong guerrillas had infiltrated during Tet festivities, these forces attacked almost simultaneously throughout the city. The previously invulnerable U.S. Embassy in Saigon was overrun and held by Viet Cong for eight hours before U.S. Marines and Military Police could retake the complex. It took another three weeks for U.S. troops to kill or evict most VC from Saigon.
The largest battle of Tet, and the whole war, was in Hue, where the city was in enemy hands and under fire from 31 January until an assault regained control on 25 February. Four NVA battalions and six VC battalions took the city and it required the massing of four US Army battalions, three USMC battalions and eleven ARVN battalions, plus supporting air, naval and artillery assets, to retake Hue, with heavy casualties on both sides. While in control of Hue, the Communists executed about 5,800 civilians in reprisal for cooperation with the South Vietnamese government and the Americans. Returning ARVN then executed many more as VC collaborators. The house to house fighting and destruction of the ancient city by bombardment left over 100,000 homeless.
During the acute period of the Tet Offensive, 31 January to 31 March 1968, other large battles took place at the Bien Hoa air base and at the American stronghold of Tan Son Nhut. The Tet Counter-Offensive period continued through 1968 with clearing operations as U.S. units were committed in the populated areas to oppose the enemy units that had penetrated and in the uninhabited areas to block the enemy's withdrawal and to prevent reinforcement of crumbling Communist forces.
By the end of 1968 the pre-Tet level of security had been restored.
Tet Was a Disaster for the Communists
Enemy losses from allied operations during Tet were estimated to be 45,000 dead with up to 170,000 total casualties, mostly Viet Cong. American deaths were about 1,500 plus another 2,800 among Allies and ARVN. Tens of thousands of civilians died in the clashes and reprisals creating bitterness toward the VC, adding to Communist setbacks, as Tet also failed to spawn either a civilian uprising or material support among the South Vietnamese. In military terms, the Tet Offensive was a disaster for the Communists but political gains nevertheless accrued mostly to their side.
Gen. Westmoreland thought that the Communists were almost finished and asked for an increase in troop strength by 206,000 to finish them off. But, in the U.S. Tet galvanized opponents of the war who now had proof that the optimism of late 1967 was unfounded and that the war would go on indefinitely. Pres. Johnson was now influenced by new Sec. of State Clark Clifford and his panel of "wise men" who made the case that Vietnam was hopeless and it was time for the U.S. to disengage.
Rather than grant Westmoreland's requests for more troops, which would have been against most advice and would have required a politically unacceptable reserve call-up or drawdown in Europe, Johnson recalled Westmoreland to Washington, replacing him with General Creighton Abrams, Westmoreland's deputy commander, in July 1968. With Abrams U.S. policy went into reverse, moving toward a return to the pre-1965 arrangement of U.S. advisors supporting ARVN units who would bear the combat responsibility. Under the new name of "Vietnamization" the objective was to withdraw Americans from Vietnam.
On 31 March 1968, Johnson announced he would pursue peace talks with North Vietnam, and would not run for re-election, setting the stage for Richard Nixon to run for President on a platform of "Peace with Honor".