On February 7, 1965, at the height of the Vietnam war, one of President Johnson's aides wrote a memo: "The prospect in Vietnam is grim. The energy and persistence of the Viet Cong are astonishing. They can appear anywhere—and at almost anytime. They have accepted extraordinary losses and they come back for more."

A few years later, around early March 1968, President Johnson finally admitted that the war, which had already gone on too lon