The professorial four-star general with an outsized reputation hasn't been chosen as Afghanistan war commander to bring a bold new strategy to the effort. Instead, he is seen as the officer best able to make the current strategy work — and to end the squabbling between diplomats and military leaders that broke into the open and consumed Gen. Stanley McChrystal's career.
If McChrystal's staff resembled a locker room-style boy's club, Petraeus, a Princeton Ph.D., is known for running his team more like a graduate seminar.
But he can set a ferocious pace.
"He is the Energizer general," says retired U.S. Army Col. Peter Mansoor, who was Petraeus' executive officer in Iraq in 2007 and 2008. "But what he'll need is someone on his staff to make him pace himself. That was my job." Mansoor said: "His natural instinct is to run himself into the ground."
Petraeus, 57, rises early for long runs, outgunning officers half his age, and responds to e-mails in the middle of the night. The intensity has sometimes shown. Petraeus briefly collapsed during Senate testimony last week, apparently from dehydration.
He is seen as ablest to pick up the counterinsurgency battle plan exactly where McChrystal is leaving off. Petraeus was McChrystal's boss as head of U.S. Central Command in Tampa, Fla., where he was already keeping tabs on the campaign, with frequent visits to Afghanistan, neighboring Pakistan and Washington.
"He's already completely up to date on the intelligence, knows the political and military actors, and understands the region," says John Nagl, president of the Center for the New American Security.
"He'll have the support of the troops," says Mansoor. "He can just roll up his sleeves and get right to work."
Over the past two years at Central Command, Petraeus has fostered what's been described as a good working relationship with Afghan President Hamid Karzai. He knows Afghanistan's U.S. ambassador, former Gen. Karl Eikenberry, from their years together in the army.
Also important, Petraeus has established a solid relationship with the White House as one who took part in strategy reviews of Afghanistan, Iraq and Iran policies, says Michael O'Hanlon of the Brookings Institution. "He and the president know each other pretty well right now," he said, a personal relationship that was notably lacking between Obama and McChrystal.
The Afghanistan job is technically a demotion from Petraeus' current post, where he oversees U.S. military involvement across the Middle East, including Iraq and Iran, as well as Afghanistan and Pakistan and several Central Asian nations.
Yet no one who has worked with him thinks that's how he'll see it. "He's getting another opportunity to step into a war at a critical inflection point," said Nagl, a retired Army officer who worked for Petraeus in drafting the Army's counterinsurgency manual. "So this is by no means a step down."
Response to his nomination on Capitol Hill has been widely positive, and he is expected to be confirmed quickly by the Senate. Rep. Ike Skelton, a Missouri Democrat, said Petraeus' willingness to step back as a war commander shows "the measure of a man."
"He knows we have to be successful there," Skelton said.
Petraeus is expected to continue McChrystal's strategy in Afghanistan in large part because it is based on Petreaus' own ideas about beating an insurgency. That plan calls for more troops to bolster security, while limiting the use of firepower in order to win the support of the local population.
In Brussels, NATO Secretary-General Anders Fogh Rasmussen said operations in Afghanistan will continue as planned and "will not miss a beat."
The post will mean another long stint overseas for a man who had three tours in Iraq. His return to the U.S. did not mean much more time with his wife, Holly, in Tampa, however. He spent more than 300 days on the road last year, even as he battled prostate cancer. He was later declared free of the disease after a course of chemotherapy.
He has a favorite expression: "Luck is what you call it when preparation meets opportunity."
There's little question he's prepared for his latest opportunity. It remains to be seen whether that will be lucky.
Associated Press writers Anne Gearan in Washington and Slobodan Lekic in Brussels contributed to this report.