WASHINGTON — This was another year of the vanishing center in America. Despite the election of a president who promised to govern across party and racial lines, partisan division seemed to engulf nearly every important institution and topic — with one notable exception, and that was the U.S. military.

So at year’s end, I want to examine the person who came to symbolize the military’s apolitical unity, Adm. Mike Mullen, the chairman of the Joint Chiefs of Staff. A year from now, I’d love to be able to say there are more Mullens in our national life and fewer Rush Limbaughs.

Mullen managed the military’s transition from George W. Bush to Barack Obama, from surging in Iraq to withdrawing U.S. troops. He worked with the new president while Obama painstakingly made the decision to escalate in Afghanistan. Through it all, Mullen managed to remain out of the limelight most of the time, which is where a military leader ought to be.

Mullen isn’t a flashy operator. He botches his syntax, and he doesn’t always finish his sentences. A friend of Mullen’s likens him to the actor Walter Matthau — a big man with a meaty face; fit, but slightly rumpled; at once wry and grandfatherly.

In a speech several months ago in New York, Mullen described himself as the military version of Rodney Dangerfield. He noted that when a woman asked at a dinner party what he did at the Pentagon, he told her that he was the president’s top military adviser: “’Oh my goodness, Gen. Petraeus, I’m so sorry,’ she blurted. ‘I did not recognize you.’”

Mullen made his way up in one of the unglamorous parts of the Navy — the destroyer fleet’s engineering branch. His nickname back then was “Midnight Mike,” because he worked so hard. His father had been a Hollywood publicist, handling the likes of Ann-Margret, which probably helped the young officer cope with the big egos of Navy commanders.

Mullen got the chairman’s job because he had developed a reputation as an unselfish leader — something that isn’t always true in a Pentagon where each service struggles to protect its turf. When Mullen was chief of naval operations back in 2007, a top aide to Defense Secretary Bob Gates asked Mullen what worried him most. His generous answer — “the U.S. Army” — is said to have convinced Gates that he was the right person for the chairman’s job.

Mullen knew there would be a presidential turnover during his watch as chairman, and he began preparing for it early. He wrote an article in July 2008, when some soldiers were nervous about having a Democrat in the White House, stressing that “the U.S. military must remain apolitical at all times and in all ways.”

Advising the new president on the Afghanistan War has been the trickiest part of Mullen’s job. An early challenge was replacing Gen. David McKiernan as commander. When McKiernan didn’t answer an important question during a video briefing for Gates, the chairman advised his boss: “I don’t think we have the right guy there.” Gates concurred, and Mullen recommended Gen. Stanley McChrystal as a replacement.

During the long White House review of Afghan policy, Mullen had the delicate task of advising, but not pushing, the president. In congressional testimony in September, he expressed his personal view that more troops were needed — for which he was rebuked by Rahm Emanuel, the White House chief of staff. Mullen kept his head down after that.

The Afghanistan decision tested the civilian-military balance. Some liberals worry that Mullen and the generals co-opted the president; conservatives argue that Mullen unwisely endorsed the president’s July 2011 withdrawal timetable. But the decision achieved that rare Washington moment of a consensus both sides could live with.

Mullen has his critics: Some argue that he has been too much the “good cop” with the Pakistani military, leaving other administration officials to prod them for more help against al-Qaida. And his problem-solving temperament will be tested next year by Iran. Mullen very much wants to avoid another war in the region, but he told commanders last week: “Should the president call for military options, we must have them ready.”

Meeting with troops this month in Afghanistan, Mullen offered some advice that revealed a lot about his own leadership style — modeled on his hero, Gen. George C. Marshall. “Lead quietly,” he told them, “lead listening.” That’s a sentiment that wasn’t heard often enough in 2009 in a noisy Washington.

David Ignatius is a Washington Post columnist. His e-mail address is davidignatius@washpost.com.