His stories about days in Vietnam as a platoon leader added a certain piquancy to his lectures on Vietnam and American Culture. He told students of patrolling near My Lai shortly before the massacre in 1968, and how, while serving at Gen Westmoreland's HQ in Saigon, he had been surprised to discover the general had six sets of fatigues cleaned and pressed every day.
It gave the students a vicarious thrill. They were not just hearing about history but seeing it through the eyes of a participant. Except that the nationally-renowned Prof Joseph Ellis (57), Pullitzer prize-winning author of a Thomas Jefferson biography, did not serve in Vietnam, as the Boston Globe revealed last week to his stunned students and faculty colleagues. He spent his war teaching history at West Point.
His college, the small all-women's Mount Holyoke in Connecticut, has set up an inquiry and he has suspended his lecture course while the world of historical scholarship has reeled.
While "resume padding" is scarcely new to academia, Prof Ellis's elaborate embroidering of his own role has shocked historians who see themselves as having a special responsibility to intellectual honesty in research and who wonder why someone whose authority was already well-established needed to pull crowd-pleasing tactics worthy of second-rate politician. Prof Ellis has apologised and, apart from one highly publicised lecture in Washington on Friday, has retreated in distress to the comfort of his family - to focus on his "personal shortcoming".
He is not the first. Recently an Oklahoma professor apologised for telling his students he had been a Navy Seal and a judge was found to have lied about a CIA and Vietnam career to get himself appointed.
Mount Holyoke, which has an honour code among students who sit exams unsupervised, is said to be agonising about what to do about a much-loved 30-year staffer who has been dean of its history faculty. The dissembling is seen by many as a personality flaw with no relevance to the professor's writings. The Boston Globe, for example, makes no allegations about their historical veracity.
But some people are wondering whether the author does not inevitably pour a bit of himself into his scholarship, particularly biography. In his Jefferson biography, American Sphinx, more than one commentator has noted, the academic explains his fascination for his subject as a reflection of his sense that the two have much in common. Regarding Jefferson's "talent for self-deception", the writer "learned to disguise my insecurities behind a mask of enigmatic silence".
Prof Ellis wrote: "My affinity for Jefferson is more personal than scholarly." But did he cross the line from the inevitable and essential empathy of the biographer for his subject to the writing of proxy self-justification? Until the Globe story, no-one would have asked the question.