The Tet Offensive 40 years ago on Thursday is seen as the decisive battle of the Vietnam war, a wave of urban attacks that broke the will of a superpower bogged down in a faraway conflict.
In the early hours of January 31, 1968 an estimated 70,000 North Vietnamese regulars and guerrillas simultaneously attacked more than 100 towns and cities in South Vietnam, including the former Saigon and some 35 provincial capitals.
The audacious offensive, which violated a truce marking the traditional Tet Lunar New Year, caught US and South Vietnamese forces off-guard and took the war from the countryside into the cities and towns. Although a military disaster that saw tens of thousands of communist soldiers killed, it proved a psychological victory by shattering the morale of the American public and their leaders, historians say.
As the US anti-war movement grew, President Lyndon B. Johnson recalled General William Westmoreland and announced his own retirement. By May Washington and Hanoi had started the Paris peace talks.
"After the offensive, the American soldiers were fighting to withdraw with honour, they were no longer fighting for victory," said Lieutenant General Nguyen Dinh Uoc, former head of Vietnam's Institute of Military History. US historian Larry Berman agreed Tet blew away LBJ's and Westmoreland's assertions that there was a light at the end of the tunnel and victory was around the corner.
"If 550,000 American forces in-country could not secure Saigon and other cities from this type of surprise attack, what was it going to take? The American public and the president were not willing to find out," Berman said.
The offensive technically started with several attacks early on January 30. The battle raged for more than 3 weeks in the old imperial capital of Hue, where communist troops killed hundreds before South Vietnamese troops and US marines took back the central Citadel.