Christian Appy jokes that, to many of the students who take his class about the Vietnam War, the long struggle seems almost like “ancient history.”

But as the University of Massachusetts Amherst history professor sees it, the Vietnam War has left a long, tangled legacy that is still very much with us today.

Appy, who teaches a number of courses on modern American history, is the author of three books on Vietnam, including “Patriots,” an acclaimed 2003 oral history of the war in which he interviewed some 350 people — Americans, Vietnamese, soldiers and generals, journalists, antiwar protesters and government officials — who had been touched by a bitter struggle that cost more than 58,000 American lives and more than 3 million Vietnamese ones.

Appy’s newest book, “American Reckoning: The Vietnam War and our National Identity,” offers a different look at the war and its aftermath. Part history, part essay, part cultural study, “American Reckoning” examines how the war affected our national self-perception and how it has come to be viewed today — as well as how it’s shaped our foreign policy in a new century that, so far, has been marked by our involvement in long, indecisive wars in Iraq and Afghanistan.

Among a number of positive reviews, Kirkus Reviews calls “American Reckoning” an excellent introduction to, and reappraisal of, the Vietnam era: “For generations who know the Vietnam War largely through movies and fiction, this well-informed and impassioned book is an antidote to forgetting and an appeal to reassess America’s place in the world.” ...