Hillary Clinton's Last Tour as a Rock-Star Diplomat Jessica Dimmock/VII, for The New York Times Secretary of State Hillary Rodham Clinton at a senior staff meeting in Washington. On May 3, the day after an artful deal to end the diplomatic crisis over Chen Guangcheng, China's now-famous dissident, unraveled spectacularly, Hillary Rodham Clinton followed a scrum of Chinese ministers around an exhibition of clean cookstoves. These are safer, portable alternatives to the crude stoves used by hundreds of millions of women in the developing world - at grave risk to themselves, their children and the planet. Not long after becoming secretary of state in 2009, Clinton took up the cookstove cause, one of what she describes as "smart power" issues - though skeptical veterans of American foreign policy tend to deride them as soft more than smart. Clinton with Laura Bush at the U.S.-Afghan Women's Council 10th-anniversary luncheon at the State Department. In September 2010, Clinton announced the creation of a partnership led by the United Nations Foundation to provide 100 million cleaner and more efficient stoves around the world by 2020, and she has since used every opportunity to implore world leaders to adopt policies to encourage their use. Among them was China's top foreign-policy official, Dai Bingguo, with whom she first raised the issue over lunch at the State Department in May 2011. Clinton can recite the arguments by rote: The smoke from poorly ventilated stoves kills nearly two million people a year, more than malaria. Foraging for wood consumes the time and effort of women and children and exposes them to attack. The stoves are a significant source of black carbon in the atmosphere, contributing to climate change. After a year of discussion, Dai agreed to put it on the agenda for their annual meetings this year in Beijing, raising the prospect that China, which accounts for more than a quarter of the world's deaths from the old stoves, would become the 33rd country to join the partnership that Clinton started. The Chinese are fussy about diplomacy and protocol - they like neither surprises nor confrontation - and months of preparation went into the meetings in Beijing. Then late at night on April 25, a week before Clinton was to arrive, she held an emergency conference call over secure lines with her top advisers at the State Department, arriving at a decision that put the entire visit at risk, not to mention years of effort to improve relations with China. Chen, a blind, self-taught lawyer who endured a prison term and ongoing harassment, had escaped house arrest in his village in Shandong Province and made his way to the outskirts of Beijing. An American diplomat secretly met with him there and reported back to Washington that he needed urgent medical treatment in the only safe place imaginable: the American Embassy in Beijing, where a doctor could examine him. After her aides briefed the White House, which traditionally does not involve itself in consular affairs, Clinton agreed. Hours later, the Americans spirited him in. The next challenge was to resolve Chen's fate in a way that wouldn't scuttle essential Chinese cooperation on the nuclear ambitions of Iran and North Korea, the worsening conflict in Syria, the fighting between Sudan and South Sudan, cyberattacks emanating from China - and cookstoves. No one close to her would dare put it quite this way, but a question at the heart of her legacy is this: As important as the plight of Chen might be, what is it compared to the deaths of nearly two million people a year from toxic smoke in their kitchens? What has been most striking about Clinton's tenure as secretary of state is at once how suited for the job she has proved to be and how improbable it once seemed, even to her. "Not in a million years," she replied by e-mail in November 2008 when her political aide Philippe Reines first told her that President-elect Barack Obama was considering her appointment, despite having derided her experience in foreign affairs as first lady during the campaign. His experience, Obama said during the primaries, was "grounded in understanding how the world sees America, from living overseas and traveling overseas, and having family beyond our shores" and "not just of what world leader I went and talked to in the ambassador's house, who I had tea with." It's true that Clinton lacked the foreign-policy experience of recent secretaries like Condoleezza Rice, Colin L. Powell or Madeleine K. Albright. Nor was she personally close to Obama in the way James A. Baker III was to President George H. W. Bush. What she possessed was energy, the dogged loyalty she displayed campaigning for Obama after she lost and, not insignificant, her fame. Clinton vacillated for days, at one point deciding to decline. Her aides say Obama would not take no for an answer; he avoided at least one phone call from her, the story goes, by having an aide explain he was in the bathroom. Ultimately, as the chief of protocol of the United States, Capricia Penavic Marshall, who has worked with Clinton since she was first lady, told me: "When asked to serve, she does. And her president asked. An earlier version of this article misspelled the surname of the foreign-service officer Aaron D. Snipe as Snipes. An earlier version of this story misstated which round of the U.S-China Strategic and Economic Dialogue Hillary Rodham Clinton attended this year. It was the fourth round, not the third.