WASHINGTON -- Last summer, as the fighting in Syria raged and questions about the United States' inaction grew, Secretary of State Hillary Rodham Clinton conferred privately with David H. Petraeus, the director of the C.I.A. The two officials were joining forces on a plan to arm the Syrian resistance.
The idea was to vet the rebel groups and train fighters, who would be supplied with weapons. The plan had risks, but it also offered the potential reward of creating Syrian allies with whom the United States could work, both during the conflict and President Bashar al-Assad's eventual removal.
Mrs. Clinton and Mr. Petraeus presented the proposal to the White House, according to administration officials. But with the White House worried about the risks, and with President Obama in the midst of a re-election bid, they were rebuffed.
A year earlier, she had better luck with the White House. Overcoming the administration's skeptics, she persuaded Mr. Obama to open relations with the military rulers in Myanmar, a reclusive dictatorship eager to emerge from decades of isolation.
As she leaves the State Department, the simplest yardstick for measuring Mrs. Clinton's legacy has been her tireless travels: 112 countries, nearly a million miles, 401 days on the road. Historians will point to how she expanded the State Department's agenda to embrace issues like gender violence and the use of social media in diplomacy.
"We do need a new architecture for this new world: more Frank Gehry than formal Greek," Mrs. Clinton said in a speech last week that served as both a valedictory and a reminder of why she remained the nation's most potent political figure aside from Mr. Obama.
And yet, interviews with more than a dozen current and former officials also paint a more complex picture: of a dogged diplomat and a sometimes frustrated figure who prized her role as team player, but whose instincts were often more activist than those of a White House that has kept a tight grip on foreign policy.
The disclosures about Mrs. Clinton's behind-the-scenes role in Syria and Myanmar -- one a setback, the other a success -- offer a window into her time as a member of Mr. Obama's cabinet. They may also be a guide to her thinking as she ponders a future run for the presidency with favorability ratings that are the highest of her career, even after her last months at the State Department were marred by the deadly attack on the American Mission in Benghazi, Libya.
"Secretary Clinton has dramatically changed the face of U.S. foreign policy globally for the good," said Richard L. Armitage, deputy secretary of state during the George W. Bush administration. "But I wish she had been unleashed more by the White House."
In an administration often faulted for its timidity abroad, "Clinton wanted to lead from the front, not from behind," said Vali R. Nasr, a former State Department adviser on Afghanistan and Pakistan who is now the dean of the Johns Hopkins School of Advanced International Studies.
Mrs. Clinton made her first official trip to Asia, a choice that spoke to her diplomatic ambitions as well as her recognition from the start that many big-ticket foreign-policy issues in the Obama administration -- Iraq, Iran and peacemaking in the Middle East -- would be controlled by the White House or the Pentagon.
In Afghanistan, several officials said, Mrs. Clinton hungered for a success on the order of the Dayton Accords, which ended the Bosnian War. But when her special representative, Richard C. Holbrooke, who had negotiated that agreement, fell out of favor with the White House and later died, those dreams died with him.
Then came the Arab awakening, a strategic surprise that eclipsed America's shift to focusing on Asia and plunged Mrs. Clinton into a maelstrom. It tested her loyalty to longtime allies like President Hosni Mubarak of Egypt and reinforced her conviction that anger at decades of stagnation, fueled by social media, would sweep aside the old order in the Arab world.
After Britain and France argued for intervening to defend Libya's rebels against Col. Muammar el-Qaddafi, Mrs. Clinton played an important role in mobilizing a broad international coalition and persuading the White House to join the NATO-led operation.
But it was Syria that proved to be the most difficult test. As that country descended into civil war, the administration provided humanitarian aid to the growing flood of refugees, pushed for sanctions and sought to organize the political opposition. The United States lagged France, Britain and Persian Gulf states in recognizing that opposition as the legitimate representative of the Syria people, but by December, Mr. Obama had taken that step.
Still, rebel fighters were clamoring for weapons and training. The White House has been reluctant to arm them for fear that it would draw the United States into the conflict and raise the risk of the weapons falling into the wrong hands. Rebel extremists affiliated with Al Qaeda had faced no such constraints in securing weapons from their backers.
When Mr. Petraeus was the commander of forces in Iraq and then-Senator Clinton was serving on the Senate Armed Services Committee and preparing for her 2008 presidential bid, she had all but called him a liar for trumpeting the military gains of the troop increase ordered by President Bush. But serving together in the Obama administration, they were allies when it came to Syria, as well as on the debate over how many troops to send to Afghanistan at the beginning of the administration.
Mr. Petraeus had a background in training foreign forces from his years in Iraq, and his C.I.A. job put him in charge of covert operations. The Americans already had experience in providing nonlethal assistance to some of the rebels.
The plan that Mr. Petraeus developed and Mrs. Clinton supported called for vetting rebels and establishing and arming a group of fighters with the assistance of some neighboring states. Defense Secretary Leon E. Panetta was said by some officials to be sympathetic to the idea. Mr. Petraeus and a spokesman for Mr. Panetta declined to comment.
Wary of becoming entangled in the Syria crisis, the White House pushed back and Mrs. Clinton backed off. Some administration officials expected the issue to be joined again after the election. But when Mr. Petraeus resigned because of an extramarital affair and Mrs. Clinton suffered a concussion, missing weeks of work, the issue was shelved.
In an interview last week, Mrs. Clinton declined to comment on her role in the arms debate and emphasized other steps the United States had taken. "We have worked assiduously, first to create some kind of legitimate opposition," she said. "We have been the architect and main mover of very tough sanctions against Assad."
She added: "Having said all that, Assad is still killing. The opposition is increasingly being represented by Al Qaeda extremist elements." She also said that the opposition was getting messages from the ungoverned areas in Pakistan where some of the Qaeda leadership was believed to be hiding -- a development she called "deeply distressing."
If Syria and Benghazi were low points for Mrs. Clinton, then the diplomatic opening to the military government in Myanmar, also known as Burma, was perhaps the biggest highlight. There, too, she initially met resistance from the White House and Pentagon, as well as the prospect of opposition from the Senate minority leader, Mitch McConnell of Kentucky, a stalwart supporter of Myanmar's prodemocracy leader, Daw Aung San Suu Kyi.
Once she secured Mr. McConnell's acquiescence, Mrs. Clinton sent her assistant secretary for East Asian affairs, Kurt M. Campbell, to meet the generals. When he returned, persuaded that Myanmar was poised for change, Mrs. Clinton convened a full review of whether to ease American sanctions and establish diplomatic ties.
White House aides remained wary about rewarding a repressive government. So Mrs. Clinton, in effect, made an end run, seeking out Mr. Obama directly and persuading him to send her on a historic visit to Myanmar in December 2011.
"We didn't know what was going to happen," she said. "The president basically said, 'Look, I'm behind you on this.' "
While Myanmar's progress has not been without bumps, things have progressed enough that Mrs. Clinton accompanied Mr. Obama on his own visit last fall. And it was not the only bold move of Mrs. Clinton's focus on Asia. In July 2010, she provoked a sulfurous reaction from China when she announced that the United States had an interest in helping to resolve territorial disputes between China and its neighbors over the South China Sea.
"There had been a lot of rhetoric about the pivot to Asia, but here was an issue where more U.S. engagement meant a lot to the region," said Benjamin J. Rhodes, a deputy national security adviser.
And yet, Mrs. Clinton's involvement has done little to quell the tensions. China feuded recently with the Philippines over a rocky shoal claimed by both countries, and farther north, in the East China Sea, it is enmeshed in a dispute with Japan over islands.
Mrs. Clinton insisted that her involvement had put China on notice that it could not brush off international legal norms in pursuing its maritime claims. "There's still going to be belligerence, and there's going to be a lot of very hot rhetoric," she said. "But I think we've helped support a strong case for the kind of framework we believe in."
The fruits of Mrs. Clinton's work were evident last year in the fraught, but ultimately successful, negotiation over Chen Guangcheng, the dissident who sought refuge in the American Embassy in Beijing. When an initial deal fell apart, she said, she passed a note to China's senior foreign-policy official, Dai Bingguo, that said, "You and I need to talk."
Huddling in a small room, she persuaded Mr. Dai to order his deputies to go back to the table with her team. "It was incredibly intense," she said, in an observation that could apply to so many of her days as secretary of state, "but I was always confident."nation
This article originally appeared in The New York Times.