The Tet Offensive of 1968 was widely described as the turning point of the war:

taking the American command by surprise, the Vietcong surrounded the Marine base at Khesanh and actually got as far as the U.S. Embassy compound in Saigon. The Allies quickly rallied and drove them back--but not before America had been convinced that we had suffered a serious defeat. Now Peter Braestrup had written a 1,500-page book analyzing the American press's reporting and its effects. An illuminating discussion, from which one sample. Mr. Braestrup: "Adding to the pressures was the terrible fear among the civilians in the White House. You remember that none of these men--including the President--had ever fought in a war on the ground. None of the whiz kids in the Pentagon had ever fought in a war on the ground. They were all defense intellectuals. They saw the big picture, but when the little picture got bloody and smoky, this made them nervous, and it made the President nervous."