At the end of January 1968, on the first day of a mutually agreed upon truce for the Tet lunar new year holiday, “the Communist forces in Vietnam opened a series of ferocious attacks on Saigon and thirty provincial centers. Thousands of civilians were killed and maimed and nearly a half-million people left homeless.” 
The Vietnam War was Part 2 of the Bay of Pigs. The Bay of Pigs fiasco had been initiated by the CIA. Then things went wrong and the new president, John F. Kennedy (JFK), was pressured to openly commit U.S. forces so as to wipe the ass of CIA and save it from embarrassment. But JFK would not agree to do this. Later, when CIA was up to more “fun and games” in Vietnam, again things went wrong. But this time the new president, Lyndon Baines Johnson (LBJ), agreed to cover the ass of CIA.
Before the time Bay of Pigs was being fomented, President Dwight D. Eisenhower and Secretary of State John Foster Dulles had been impressed by Ramon Magsaysay’s successful campaign against the Communist Huk guerrillas in the Philippines. They thought the same tactics might work in Vietnam. 
Edward Lansdale, an Air Force colonel, briefed Eisenhower and Dulles on the possibilities. Lansdale received a mandate from Dulles: Find a popular person in Vietnam to serve as puppet for the Invisible Government. Chosen as the stooge was Ngo Dinh Diem. 
Lansdale in Vietnam was “represented under a pseudonym in the book The Ugly American.”  That book is constantly being mentioned by persons who have obviously never read it. Get this straight: “The Ugly American” WAS A GOOD GUY! He was called “ugly” in the book just because of his appearance, as contrasted with the suave and fashionable diplomats.
Author Graham Greene patterned Lansdale as the protagonist in his book, The Quiet American. 
Around 1955, Lansdale warned Diem that he must give political freedom to opposition parties. Otherwise Vietnam would be “plagued by conspiracy.” But Diem refused to do this. 
So Lansdale flew to Washington and tried to persuade the Dulles brothers (Alan, of CIA, and John Foster, of State) to pressure Diem into political reforms. But the Dulles brothers said, “No.” 
And so it was that the influence of “ugly American” Lansdale began to fade and the CIA took his place as emissary of the Invisible Government to Vietnam. There followed from this further buildup of military and economic aid to Diem’s repressive regime. By February 1962 around 4,000 U.S. soldiers were serving secretly in Vietnam. By 1963, more than 16,000 U.S. troops were there. 
The CIA screwup for Part 2 Bay of Pigs was becoming harder to sweep under the carpet. And JFK was reluctant to pour more and more soldiers in just to enable continued CIA dysfunction.
Ah! But then occurred the assassination of JFK and the elevation of LBJ. “Gentlemen, you shall have your war,” famously says LBJ to the Joint Chiefs in Oliver Stone’s movie, JFK. (Stone, by the way, co-wrote a book which provided support for his assertions. See: JFK: The Book of the Film, by Oliver Stone and Zachary Sklar.)
Then, in 1968, fifty years ago now, came the Tet offensive. Soon thereafter, LBJ made the surprising announcement that he would not seek re-election.
——- Sources ——-
 The Ordeal Of Otto Otepka, by William J. Gill. New Rochelle, NY: Arlington House, 1969.
 The Invisible Government, by David Wise and Thomas B. Ross. New York: Random House, 1964.