He attended the McBurney School and earned bachelor’s, master’s and doctoral degrees from New York University. He taught at the Massachusetts Institute of Technology and the Carnegie Institute of Technology before joining the University of South Carolina faculty in 1972. He retired as distinguished professor emeritus of history in 2008.

His marriage to Daphne Newman Stassin ended in divorce in 1975.

He wrote two biographies of Henry R. Luce, the Time magazine magnate, but was best known for his Nazi-era scholarship in books that included “Roosevelt and Hitler: Prelude to War,” “The War That Hitler Won,” “Adolf Hitler and the German Trauma” and “Waldheim: The Missing Years,” which was published in 1988.

In reviewing “Waldheim” for The New York Times Book Review, the novelist Shirley Hazzard, who had written about Mr. Waldheim’s past in The New Republic, described the book as “important” but also “at times obtuse and often trivial.” She said Mr. Waldheim would have most certainly been aware of Nazi atrocities committed in Russia and the Balkans and concluded, “While Mr. Herzstein is probably right in assuming that Mr. Waldheim took no pleasure in such abominations, nothing in his temperament or story suggests he was affronted by them.” Mr. Waldheim retired as secretary general in 1981.

Four years later, when he was the right-wing People’s Party’s candidate for the largely ceremonial post of president of Austria, Profil, a leading magazine, published details of his wartime past. On March 4, 1986, The New York Times reported on Mr. Waldheim’s wartime service in the Balkans and his prewar Nazi associations. A few weeks later, the World Jewish Congress announced Mr. Herzstein’s findings.

Mr. Waldheim said he had never belonged to any Nazi-affiliated groups, but, in fact, he had joined the National Socialist students’ league and later enrolled in the Sturmabteilung, the paramilitary Nazi organization of storm troopers. He served under a general who led the Germans and their Croatian allies in slaughtering more than 60,000 suspected Yugoslav partisans and their families at Kozara, in western Bosnia, in 1942. Mr. Waldheim maintained at first that he had never been there, then said the medal he received for the battle had been handed out “like chocolates” to all German officers.