Charlyne Berens is professor and associate dean at the College of Journalism and Mass Communications at the University of Nebraska-Lincoln. She is the author of Chuck Hagel: Moving Forward, from which parts of this article were drawn.

Having been there makes a difference.

Crawling on your stomach in the pitch dark while you hear the clink, clink of a column of Vietcong troops winding its way through the jungle only a few feet away. Fighting house to house, doorway to doorway in Saigon during the Tet offensive. Being wounded twice and promoted twice and decorated seven times.

Chuck Hagel was there -- in Vietnam from 1967-68, during some of the most intense fighting of the war. Now he is President Barack Obama's nominee to be America's next secretary of defense, and if he is confirmed, Hagel would be the first former enlisted man ever to lead the Defense Department. It's a safe bet that what he experienced in the jungles of Vietnam would make a difference in the way Hagel would approach his job at the Pentagon.

"War is not an abstraction," Hagel wrote in a piece for the Omaha World-Herald in 2004. "I know. I've been to war."

When he was in the Senate, Hagel tried to help his colleagues understand war through the lens of the people who would actually be doing the fighting and dying. "We see war up here in very antiseptic terms," he said. "We see it in bright policy terms. In human suffering terms? No." The terms are different, of course, for someone who has been there.

Years before he arrived in Vietnam at age 21, Hagel had already been interested in international relations. His friends teased him when he started subscribing to Time magazine in junior high.

But his experience in Vietnam intensified and shaped the adult Hagel's internationalist worldview. "Integration of the United States in the world is key," he said when I interviewed him in 2004. War may sometimes be an ugly necessity, but it is international relationships that maintain stability and security, he said.

The war Hagel confronted in Vietnam was ugly, indeed. Funny thing is, he wouldn't have had to go there...