Courageous and optimistic, he knew the country he was assigned to like no other diplomat. His tragic death leaves an enormous hole in the American foreign service—and in Washington’s fitful dealings with the Arab world

Ben Curtis—AP U.S. envoy Chris Stevens attends meetings at the Tibesty Hotel where an African Union delegation was meeting with opposition leaders in Benghazi, Libya, April 11, 2011.

“Salaam alaikum. My name is Chris Stevens, and I’m the new U.S. ambassador to Libya.” With those words Christopher Stevens—the 52-year-old diplomat who was killed along with three other Americans in a September 11 attack on the U.S. consulate in Benghazi, Libya—began an online video introducing himself to the people of Libya. Though he only took up his position in May, he wasn’t new to the region. An Arabic and French speaker, Stevens had been a Peace Corps volunteer in Morocco, and after working in international trade law in Washington, served in Israel, Egypt and Saudi Arabia during his 21 years with the State Department.

But it was in Libya—where he also served as the number two U.S. diplomat from 2007 to 2009—where Stevens made his mark. His experience and credibility in a country that had long been off-limits proved invaluable during the chaotic Libyan revolution, and his work helped convince the Obama Administration to provide conclusive support to the besieged rebels. That made Stevens’s death all the more ironic—as President Barack Obama said after the attacks “it is especially tragic that he died in Benghazi because it is a city he helped to save at the height of a revolution.”

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It’s telling that less than three hours after Stevens’ death in Benghazi, Libyans had started an Arabic-language Facebook tribute page for him. On it they shared photos of the ambassador, for example, slouching down with Libyans eating local food with his hand. They also posted pictures of themselves holding candles lit in his memory.

By all accounts, Stevens wasn’t one to sit at a desk. He preferred being out of Washington and preferably out in the field. An avid hiker who grew up in California, he would often escape the embassy to roam Libya’s Roman ruins. “We served together in Syria,” says principal deputy Secretary of State Liz Dibble, “and I remember him describing a trip he took to Saladin’s castle. This was way off the beaten path in a country that was way off the beaten path.”

But if those discoveries were solitary – or done with an ever-changing lady friend – Stevens was known for his gregariousness. “He could be a party boy from time to time,” says Janet Sanderson, who first served with him in Cairo in the 1990s. “He was extremely popular and very personable. He was a lot of fun to be with. He loved sitting around talking politics until 2 a.m. and drinking endless cups of coffee and tea.”

He used his people skills to set the stage at meetings or in speeches, drawing people in. “He could hold his audience in the palm of his hand,” recalls Sanderson. “He could hold his audience on the Hill. He was great at explaining complex political environments. And he had the answers to the questions lawmakers asked, even before they asked them. Like on Libya: who were the rebels? Could they be unified? He knew all the factions, the whole landscape.”

Stevens’ knowledge of the Hill perhaps came from serving as a Pearson fellow, a yearlong exchange program for Foreign Service officers on the Hill, in Senator Richard Lugar’s office. Lugar was the top Republican on the Foreign Relations Committee.

In Cairo, Stevens made a name for himself as a tennis player. “He was this tall, blond guy,” says Sanderson. “He cut quite a figure in Cairo. It was only his second tour but he was the go-to tennis player when the ambassador wanted to impress visitors and play tennis.”

(MORE: Egypt, Libya: Fundamentalisms Unleash Havoc)

Stevens was ambitious without being cutthroat. “Type A with California laid over it,” says Dibble. He was the first in his Foreign Service class to make chief of mission. And he was fearless. As the U.S. was evacuating its embassy staff from Tripoli during the height of last year’s revolution, Stevens was negotiating to get dropped off by barge in Benghazi so he could work with the opposition leaders to help form a new government. He knew Benghazi perhaps better than any U.S. diplomat. “Oh, we had to go through all sorts of machinations to get him to Benghazi,” recalls Sanderson, who recently left her post as deputy assistant secretary for Near Eastern Affairs. “But he took to it like a duck to water. He became so integral on the ground.”

He was known particularly for his calm under fire. “Even when things were sort of crazy and we’d be talking on the phone he could make me laugh,” says Sanderson. Adds Dibble, “he never ran, never rushed. I never saw him flap or get fussed.”

Stevens was also known for mentoring younger Foreign Service officers. “From our perspective as we’re coming up the ranks when folks get to be ambassadors, they become very very serious and sometimes lose a little bit of the vitality and idealism and optimism that they had when they were younger,” says Aaron Snipe, a spokesman for the Bureau for Near Eastern Affairs who was friends with Stevens. “Chris had that optimism and he took that with him.”

Echoed Dibble, “He felt that he could make a difference, without being Pollyanna ish about it. He did it one step at a time. I think he’d probably be embarrassed by what people are saying about him. I think he’d probably say he was just being himself, doing his job. His outlook in life was ‘the glass is half full’ in any situation, no matter how tough. And he has served in some of the toughest places that we have.”

The American diplomatic community will mourn Stevens, who became the first U.S. envoy to be killed in the line of duty since 1979. But the world may miss him more. Libya and the other nations remade by the Arab Spring are in the midst of historic change. “He had a dream of making a difference in Libya and I think he was,” says Dibble. “I think he had a lot of hope for Libya, for this tremendous transition it’s going through.” The new democracies of the region need to rebuild free societies out of the ashes of autocracy, while shunning the temptation of religious extremism. Stevens could have helped that process along. As Secretary of State Hillary Clinton put it: “The world needs more Chris Stevenses.” And it needs them now more than ever.

MORE: Before Libya: U.S. Ambassadors Killed in the Line of Duty