28 January is the fiftieth anniversary of the beginning of the North Vietnamese Tet Offensive. When it happened, I was in the Bien Hoa area, just north of Saigon. I had been in the highlands until the previous December, supporting U.S. troops during the battle of Dak To—see my New York Times article about that at https://www.nytimes.com/2017/11/03/opinion/vietnam-tet-offensive.html?action=click&pgtype=Homepage&clickSource=story-heading&module=opinion-c-col-right-region®ion=opinion-c-col-right-region&WT.nav=opinion-c-col-right-region
As an employee of the National Security Agency (NSA), my job during my thirteen years on and off in Vietnam was the intercept and exploitation of the communications of the invading North Vietnamese. When I arrived in the Saigon area in December 1967, I was surprised to see the same patterns in communist communications that I’d seen in the highlands that winter—the establishment of forward command posts and watch nets (staying in contact twenty-four hours a day), movements of forces toward tactical targets, reconnaissance units activated. The same activity was going on all over South Vietnam. North Vietnamese units throughout the country were preparing for battle.
At my behest, NSA pulled together the data and warned that a country-wide offensive was about to begin.
But MACV (Military Assistance Command, Vietnam, the senior U.S. military command in South Vietnam) didn’t believe the warning and didn’t prepare. The country-wide attacks came as a surprise.
According to Wikipedia, “the offensive was countrywide and well coordinated; eventually more than 80,000 North Vietnamese and Viet Cong troops struck more than 100 towns and cities, including 36 of 44 provincial capitals, five of the six autonomous cities, 72 of 245 district towns, and the southern capital. The offensive was the largest military operation conducted by either side up to that point in the war.”
The superiority of the U.S. military meant that not one of the North Vietnamese attacks was successful in the long term. All were eventually defeated, and North Vietnamese losses were enormous. The uprising by the South Vietnamese populace against the U.S forces, expected by the North Vietnamese, never materialized.
Despite the U.S. military victory, the American people turned against the war. The force of the Tet Offensive belied U.S. government assertions that the Vietnamese Communists were about to be defeated. The war in Vietnam became so unpopular that the U.S. withdrew its forces in 1973. I stayed on in Vietnam, heading the covert signals intelligence operation and escaped under fire when Saigon fell to the North Vietnamese two years later.