On Jan. 31, 1968, Lt. Col. Roy Flint arrived at a village 80 miles north of what was then called Saigon to take command of a United States Army battalion. That same day, the Tet offensive exploded across Vietnam and into Colonel Flint's war. A rocket and a mortar attack accompanied Flint's first hours in his battalion command center. Shortly thereafter an ammunition dump blew up.
At noon the next day, Flint saluted the outgoing commander, stepped into a command post helicopter, and found all four of his battalion companies already engaged in fighting the enemy.
``That was really kind of a surprise,'' says Flint, now a brigadier general and dean of academics at the US Military Academy.
Flint was far from the only American commander in the country then experiencing that reaction.
The 1968 Tet offensive, a series of bold communist attacks throughout South Vietnam, startled a US High Command that had judged the North Vietnamese and their Viet Cong guerrilla allies to be almost shattered.
By stretching their forces thin to hit many places, the Communist Vietnamese almost ensured that Tet would be a military defeat. But by graphically demonstrating the extent of their commitment, they raised a specter of endless bloodshed that daunted the US public.
``Tet 1968 ended any hope of a US-imposed solution to the war,'' writes retired Gen. Bruce Palmer Jr., former Army vice-chief of staff in his book, ``The 25 Year War.''
In the months prior to the Tet attack, US analysts had suspected that trouble of some sort was coming, according to General Palmer, who at the time was Army deputy in the country. But their estimates as to the power the enemy would be able to bring to bear were, for the most part, far too low. A number of military intelligence analysts, for instance, were wrongly judging that Viet Cong guerrillas were so hard pressed in many sectors that their groups had fragmented and were being forced to lie low.
Estimates changed overnight at the end of January. Violating a truce they themselves had declared for Tet, the Lunar New Year holiday, some 70,000 Communist troops launched a chain of surprise attacks against 100 targets.
US bases, as well as cities and towns, were hit. At the Bien Hoa air base near Saigon, fighter jets were unable to take off for 48 hours as Viet Cong shelled the runways.
Even the capital, Saigon, was not safe. Four thousand troops in small teams created havoc in and around the city, with a suicide squad fighting their way into the US Embassy compound.
It was perhaps this fighting, easily accessible to TV cameras, that most deeply affected the US public - and US soldiers.
Col. Carl Gustafson, chairman of the Department of Military Strategy at the Army War College, was then an Army major assigned to a public affairs office in Saigon. He remembers mingling in street markets, feeling perfectly safe, on one day - and then on the next, standing guard on city rooftops.
``There was a roof garden at the Rex Hotel,'' he says. ``We'd stand up there in the evening and watch tracers being fired outside of town. It looked like the whole skyline was aflame. You sat and said to yourself, `I don't know what's going on,' because at that time we felt we had the war pretty well won.''
The initial shock of the majority of the attacks was over in about a week. American firepower rolled back the Viet Cong, and even the North Vietnamese regular Army, by sheer weight of metal. Fighting in the bitterest battles, such as the fight for the ancient city of Hue, lasted somewhat longer. By early March the US command in Vietnam judged that the enemy had lost some 50,000 troops, as opposed to 2,000 US and 4,000 South Vietnamese dead.
US officers who were there remember that at the time the Tet attacks were beaten back they felt American forces had won an important victory.
``The local forces and the Viet Cong main force units were virtually destroyed,'' said Gen. William Westmoreland, Army chief in Vietnam during Tet, to the Associated Press last week. ``The North Vietnamese Army took a terrible beating. It took them about two years to recover.''
Yet Tet turned out to be a strategic victory for the Communists. Merely by demonstrating their own will, they attacked the resolve of the American people and political structure.
In explaining why Tet was a strategic US failure, retired Army Col. Harry Summers Jr. in his book ``On Strategy'' quotes the 19th-century military analyst Karl von Clausewitz: ``Not every war need be fought until one side collapses. When the motives and tensions of war are slight, we can imagine that the very faintest prospect of defeat might be enough to cause one side to yield.''
Tet alone didn't alter US public attitudes toward the war. As Stanley Karnow notes in his book on the war, US public support for the conflict as measured by opinion polls had already been sliding downward for two years.
But Tet deepened the feeling that Vietnam was a bottomless pit, and it caused President Lyndon Johnson's popularity to plunge. On March 31, President Johnson announced that he would not run for reelection.
General Flint now teaches a course on the Korean and Vietnam wars to West Point cadets. He calls Tet a ``midcourse correction,'' the psychological impact of which forced a number of changes by the US government. Among other things, the US began the process of turning more of the war over to the South Vietnamese after the offensive started.
Some US officers still believe that distorted media coverage of Tet snatched defeat from the jaws of victory. Flint, for his part, says that today he remembers the week of Tet fighting as a time of great intensity.
``We were keen. Our senses were sharp as a fine clock. You sensed noises,'' he says. ``You sensed changes in shading in the jungle.''
Chronology of the Tet offensive The Tet offensive was the major turning point in the United States war in Vietnam. For the US, it was a military victory in the field - but a political defeat at home. Some key dates: Jan. 27 National Liberation Front (Viet Cong) starts a traditional week-long cease-fire for Tet, or Lunar New Year. Jan. 30 Allied truce period begins. More than half of South Vietnamese troops in Saigon return home for holidays. Jan. 31 Viet Cong fighters launch surprise assault on more than 100 cities and towns, including 36 of 44 provincial capitals. In Hue, 7,500 Viet Cong and North Vietnamese troops storm ancient provincial capital. Feb. 7 Viet Cong capture Lang Vei outpost near Khe Sanh and hold positions in Hue and the outskirts of Saigon. They had already withdrawn from other urban areas. Feb. 18 Viet Cong launch second round of attacks. Mortar bombardments hit 45 towns and military installations. Feb. 24 After more than three weeks' occupation, North Vietnamese pull out of Hue under heavy pressure from US Marines. March 31 US President Lyndon Johnson, in first nationwide speech since Tet, announces that the US will halt bombing over three-quarters of North Vietnam. He bids Hanoi to start peace talks, and unexpectedly says he will not run for reelection.