The last two installments of the Burns-Novick documentary, The Vietnam War, broadcast last Thursday and last night, dealt with 1967 and 1968 in Vietnam. I was there part of both years and was deeply involved the Dak To battle (1967) and the Tết Offensive (1968). The Burns-Novick film suggested broadly that U.S. forces were alerted in both instances before the North Vietnamese attacked. I can verify that. I was instrumental in issuing the warnings, derived from signals intelligence—now declassified.
I wrote some months ago in this blog about the Cassandra Effect, the failure of U.S. commanders to believe or act on warnings from signals intelligence. It happened to me so often that I coined the term. The Cassandra Effect was in full force for both Dak To and Tết. General Westmoreland at MACV and the commanders of both the 4th Infantry Division and the 173rd Brigade were briefed on the signals intelligence evidence of North Vietnamese plans. They took no action to prepare. The rest is history.