In his sprawling, captivating 1972 masterpiece, "The Best and the Brightest",
the journalist David Halberstam asked the central question about America's war in Vietnam:
"What was it about the men, their attitudes, the country, its institutions and above all the era
which had allowed this tragedy to take place?"
They were "the best and the brightest", after all.
Why did it happen?
Halberstam's answer, repeated by countless authors since, contained two parts: hubris and ignorance.
American planners, presiding over the greatest military and economic power in the history of the world,
believed that with the resources at their disposal, as well as their intellectual prowess and deep experience,
they could wage and win the conflict.
They were "swept forward" by faith in their own and their country's invincibility.
But they lacked a sense of history, as well as an understanding of their adversary
and the obstacles that stood in the way of victory.
Robert McNamara, who as secretary of defence was one of the architects of the war,
later offered substantial endorsement of Halberstam's thesis.
Writing in his 1995 memoir, "In Retrospect", he lamented that he and other leaders
were ignorant of Vietnamese history and of Ho Chi Minh's nationalist motivations.
They saw a monolithic communist threat where none existed, and in their arrogance
failed to fully examine the stakes of the struggle and whether success was truly achievable at a reasonable cost.
"If only we had known" became a kind of mantra for the latter-day McNamara.