In a move that surprised many Yale undergraduates and several historians at rival institutions, the University has denied tenure to popular history professor Mary Habeck GRD ’96, a military historian.

The senior faculty of the History Department voted last week not to tenure Habeck, who is completing her ninth year of work at Yale, several professors said this week. Sources would not say whether the decision was unanimous or split, citing the department’s confidentiality rules. Habeck is still scheduled to teach next year, but she will leave Yale in 2005 due to a University policy requiring untenured professors to leave Yale after their 10th year.

“I regret it tremendously,” history professor Cynthia Russett said Tuesday. “She did wonderful service to the Yale department. She’s really an admirable colleague and I regret that she won’t be with us.”

History chairman Jon Butler and several other senior professors, as well as Habeck, declined to comment for this article.

When evaluating tenure decisions, departments at Yale and many other universities judge a professor’s scholarship, teaching ability and citizenship in the school. Habeck, some Yale professors said, has been “wonderful,” at least as a teacher and department citizen.

Several Yale professors declined to comment on the specifics of Habeck’s case and the evaluation of her scholarship and said they receive “very strong instructions about confidentiality.” But some historians at other institutions said Habeck’s scholarship is on par with the best in her field.

Stanley Payne, a senior history professor at the University of Wisconsin-Madison, has reviewed Habeck’s prospectus for her upcoming book on the Spanish Civil War and said it broke new ground in an impressive way.

“She has really opened up materials from there like no other scholar, particularly with regard to Spain but also to other places as well,” Payne said. “The originality of her work is important — It’s not just a matter of simply doing work, but the intellectual level of her analysis is of a height and a quality that really makes it very special work.”

Habeck’s departure will leave the department without a military and weapons specialist, said Marcus Jones GRD ’00, a long-time Habeck teaching assistant.

This will not be the first time in recent years that a Yale military historian has left for another position. In the spring of 2000, political science professor Allan Stam, who taught a popular lecture course called “Society and War,” left Yale for a promised tenured position at Dartmouth University after teaching at the University for four years.

“I think every indication has been that Yale is trying to move out of the business of military history altogether, no matter how big an appeal it has for undergraduates,” Jones said. “I think it’s a mistake myself. This institution used to have a major face in military history. We don’t really have one outside of Mary Habeck.”

Jones said it is “ridiculous and naive” not to have a military historian among the department’s senior ranks. But he added that Habeck has still not hit her stride as a scholar and suggested that may be why Yale declined to tenure her.

“She’s a good academic. Whether she’s a great military historian is open to question,” Jones said. “You can’t tell at this point in her career.”

Habeck’s undergraduate courses on military strategy, weaponry and war have been wildly popular. Her lectures have nearly filled the Law School Auditorium and SSS 114, two of the University’s largest lecture halls, some of her students said.

Jeremy Ershow ’06, a history major who took Habeck’s “U.S. Military, War and Society” last year and is one of Habeck’s sophomore advisees, called Habeck “the most compelling lecturer that I’ve had at Yale.”

“I’ve heard a lot of history lecture classes, and what does it say when you allow your best lecturer to walk?” Ershow said. “There’s a tremendous interest and a tremendous appetite on this campus for the courses that she teaches — there’s clearly a great demand for Mary Habeck and her courses.”

Habeck has developed a strong rapport with students on the men’s heavyweight crew team. Many rowers enroll in her seminars together and frequently eat dinner with Habeck, rower Matt Brown ’06 said.

History Director of Undergraduate Studies Frank Snowden said the department has not decided whether it will hire a military historian to replace Habeck in the junior ranks.