SHERYL GAY STOLBERG – It has been nearly half a century since a young antiwar protester named Tom Hayden traveled to Hanoi to investigate President Lyndon B. Johnson’s claims that the United States was not bombing civilians in Vietnam. Mr. Hayden saw destroyed villages and came away, he says, “pretty wounded by the pattern of deception.†Now the Pentagon — run by a Vietnam veteran, Defense Secretary Chuck Hagel — is planning a 50th anniversary commemoration of the Vietnam War. The effort, which is expected to cost taxpayers nearly $15 million by the end of this fiscal year, is intended to honor veterans and, its website says, “provide the American public with historically accurate materials†suitable for use in schools. But the extensive website, which has been up for months, largely describes a war of valor and honor that would be unrecognizable to many of the Americans who fought in and against it.