(AP Photo/Patrick Semansky)

Every year on Veteran’s Day my thoughts turn to Donovan Campbell, a former student at the center of one of the most unexpectedly emotional moments I’ve experienced in my 25 years as a professor at Harvard Business School. His story highlights for me the debt of gratitude we owe those who serve our country. It has also served as a personal reminder of the important role business schools should play in enabling members of the military to transition successfully back to civilian life.

The incident took place in 2006 in a first-year MBA course on leadership and organizational behavior. We had asked students to watch the 1949 film “Twelve O’Clock High,” starring Gregory Peck, about a World War II Air Force squadron making daylight bombing runs against heavily fortified German factories. Peck’s character is charged with turning around this unit whose morale is plummeting in the face of repeated high-risk missions and horrible casualties. At one point in the film, he and his medical officer debate how to demand “maximum effort” from soldiers who could die at any moment.

One of the standard questions I ask when teaching the class is: “Does anybody really know what it means to ask a team for maximum effort?”

As soon as I asked the question, Campbell’s hand shot up. I didn’t yet know him very well, but I knew he’d attended Princeton and was gifted intellectually. I also knew he'd been commissioned in the Marine Corps post-9/11 and had come to Harvard Business School after a tour in Iraq. I’d learned to use his experience judiciously. Whenever the class was flagging, I called on Campbell, as typically his thoughtful comments would reinvigorate the discussion.

When I called on him this morning, however, something unusual happened. He started to speak about his experience with war, but after a moment stopped and began to shake. Then he began to cry. This wasn’t a trickle of tears; it was uncontrollable sobbing. After about a minute, he ran out of the classroom. One of his closest friends, a former Army Ranger, ran after him.

Campbell returned the next day embarrassed, but everyone rallied to support him. As a class, we thanked him—not only for his service to our country, but for the emotion he showed us a day earlier. It was a vivid illustration that vulnerability is not incompatible with leadership. Too often, students think leaders must be strong for others or "the rock" of their organizations. We've instead come to realize that expressing and understanding the full range of human feeling is a critical component of leadership development, and that your own leadership approach should align with your most deeply held values.

In the coming months, I got to know Campbell much better. I learned that he’d been a lieutenant in charge of one of the first platoons of Marines in Ramadi. They had arrived during the period when it appeared the United States had won the war. But in fact, his unit became one of the first to experience the insurgency’s growing strength and sophistication, as evidenced by the use of children as decoys, IEDs and remote detonators. Campbell’s unit suffered extraordinary casualties. In short, he’d experienced a real-life version of “Twelve O’Clock High.”

Campbell ultimately did a great job in his classes. He also used his time in business school to process what he’d experienced in battle and spent much of his second year writing a memoir about his time in Iraq—a book called “Joker One” (the radio call sign of his 40-man infantry platoon), which examines issues of leadership, faith and courage. It was published in 2009 and became a New York Times bestseller.

In my time at the school, I have met many other veterans like Campbell who have served and sacrificed in inspiring ways. Roughly 50 new MBAs every year come from the military, many having been in active combat duty. Still, it is a group that all of us who lead this country’s business schools need to think about even more.

Business school can be a pathway for integrating our service members back into civilian life, and for finding new ways to engage their intellect, integrity and leadership at home. While a few return to the military after graduation, most take jobs in the private sector—and in those jobs, many of them become advocates for hiring other veterans, doing their own small part to solve the challenge of post-military employment. In their civilian lives, these veterans continue to provide leadership in service of society. Donovan, for instance, accepted a job as a manager for Pepsico after graduation, then became COO at a smaller printing company, and is now director of operations for an energy company.

“When I encourage young, talented veterans to consider applying to Harvard, they have trouble conceptualizing an Ivy League institution that isn’t reflexively anti-military,” Donovan once said. While Harvard Business School’s relationship with the military goes back many decades—during World War II, our campus was converted to a training school for managers and officers heading the U.S. war effort—breaking down the divides, both real and perceived, is still something our business schools have to work on.

As I look back, I feel privileged to have witnessed the way a single moment in the classroom could have such a profound impact on both a veteran’s readjustment and his classmates’ greater understanding of what leadership really is. It’s also a reminder to me that enduring ties between our business institutions and the military are crucial if we want, ultimately, to develop leaders who make the world a better place.

Nitin Nohria is dean of the Harvard Business School.

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