Christian Appy writes in Salon.com: ‘My main argument is that the Vietnam War shattered the central tenet of American national identity—the broad faith that the United States is a unique force for good in the world, superior not only in its military and economic power, but in the quality of its government and institutions, the character and morality of its people, and its way of life.

A common term for this belief is “American exceptionalism.” Because that term has been bandied about so much in recent years as a political slogan and a litmus test of patriotism, we need to be reminded that it has deep roots and meaning throughout our history. In many ways the nation was founded on the faith that it was blessed with unrivaled resources, freedoms, and prospects. So deep were those convictions they took on the power of myth—they were beyond debate. Dissenting movements throughout our history did little to challenge the faith.That’s what made the Vietnam War’s impact so significant. Never before had such a wide range of Americans come to doubt their nation’s superiority; never before had so many questioned its use of military force; never before had so many challenged the assumption that their country had higher moral standards.’