Five years ago today, insurgents bombed the U.N. headquarters in Baghdad. Included in the dead was Sergio Vieira de Mello, the legendary diplomat who showed the world what a new, activist style of U.N. diplomacy could look like. Just out from the Washington Independent: an overview of his legacy.

Vieira de Mello’s biographer, the human-rights expert and former Barack Obama adviser Samantha Power, agrees. "Whether on Darfur or on Georgia," Power wrote in an email sent from Brazil, where she is commemorating the diplomat’s life, "one doesn’t feel today as if there is an international official (unaffiliated with his country’s national agenda) who can be relied upon to be sent into a crisis, suss the scene and, while not a miracle worker, max out on what can be achieved — through negotiations, through the mobilization of international resources (Sergio was a hell of a salesman once he got back to capitols), etc."

Vieira de Mello still looms large five years after his death — and his legacy is a new breed of U.N. diplomat. "Up until the early 1990s, the U.N. was mostly a diplomatic forum," explained James Traub, a writer for the New York Times magazine and author of "The Best Intentions: Kofi Annan and the U.N. in the Era of American World Power." "When it engaged in big nation-building and peace-keeping actions, a whole new generation arose who had real-world experience in unbelievably trying settings, involving deep and difficult issues of sovereignty."

To add one thing to this: I could never have written this piece without the diligent and thankless assistance of my friend Mark Leon Goldberg, who made many wise recommendations to me about where to turn for insight on Sergio and who helped connect me with sources. Mark’s own reflections on Sergio’s life and legacy are passionate and eloquent.