David Petraeus is the most famous general of his generation and his 21st-century version of "boots on the ground" counterinsurgency saved George Bush's ill-fated war in Iraq, and may yet save President Barack Obama's double-down surge in Afghanistan.
His downfall is all the more stunning given that Mr. Petraeus was a politically savvy heavyweight in Washington with a publicly lauded track record both in Iraq and Afghanistan before taking over the CIA. And on his watch, that CIA emerged as perhaps the primary instrument of power in the war against terrorism, even though the Obama administration has dispensed with that Bush-era term.
As CIA director, Mr. Petraeus was the President's hand-picked commander of America's murkiest and most controversial global assassination effort: the tracking, targeting and elimination – usually by Hellfire missile fired from unmanned Predator drones – of alleged Islamic extremists.
With a confrontation with Iran looming over the Iranian nuclear program, Syria in flames and much of the Middle East struggling with transitions and the impact of the Arab Spring, the CIA's role as American's foremost spy agency is more crucial than ever. And with the agency already at the centre of a firestorm over its handling – or failure to anticipate – the attack by Islamic militants that killed four Americans in Libya, the CIA can ill afford turmoil at the top.
Even before Mr. Petraeus's hasty resignation, Congress was clamouring to hear from the CIA what it knew, and when, about the attack on the U.S. consulate in Benghazi. Now the ex-director will almost certainly be hauled before a hearing to explain not only what he knew, but whom he told.
"I have no doubt now that we will need to talk with David Petraeus and we will likely do that in closed session. But it will be done one way or another," Senator Dianne Feinstein, the California Democrat who chairs the powerful intelligence committee, said Monday.
Mr. Petraeus, who retired from the military to head the CIA in mid-2011, was due to testify Thursday. Not any more, although he may be called later as the probe widens into who knew what and when.
Lurking behind the salacious details of the affair and resignation is the far-more-serious issue of whether Mr. Petraeus disclosed intelligence secrets to his lover, Paula Broadwell, a former homecoming queen, reserve officer and author of the biography All In: The Education of General David Petraeus.
Unconfirmed reports say Captain Broadwell, a West Point graduate who outran all her male classmates to be named the elite's military academy's fittest cadet, didn't become Mr. Petraeus's mistress until the summer of 2011, after he retired. But a recent speech casts doubts on claims the affair ended months ago.
In a speech on Oct. 26 to her alma mater, the University of Denver, she inexplicably knew several details of the attack on the consulate on Benghazi.
"Now, I don't know if a lot of you heard this, but the CIA annex had actually, um, had taken a couple of Libyan militia members prisoner and they think that the attack on the consulate was an effort to try to get these prisoners back. So that's still being vetted," Capt. Broadwell, 40, said during the question-and-answer session at Denver.
Mr. Petraeus was always a high flyer. He famously took then-candidate Obama on an open-door helicopter tour of Baghdad. And when Mr. Obama suddenly needed a new commander in Afghanistan – after the incumbent was caught disparaging the man in the Oval Office – he turned to the wiry, intellectual fitness freak. So Mr. Petraeus, a career military man, went back to a combat command, attempting to do in Kabul what he had done in Baghdad.
When he moved to the CIA just over a year ago, the role was seen as the perfect culmination to a warrior's career. Mr. Petraeus expanded the drone war, sending Predators into more planes against more targets in what may become known as the Obama doctrine. Now it, and the retired general, faces new scrutiny.
David Petraeus, 60. Commanded forces in Iraq and Afghanistan, reaching rank of four-star general. Left the U.S. Army to become Barack Obama's choice as director of the Central Intelligence Agency in September, 2011.
Paula Broadwell, 40. Former graduate student at Harvard's Kennedy School of Government and reserve U.S. Army major working for military intelligence.
Ms. Broadwell meets Mr. Petraeus in 2006 at Harvard where Mr. Petraeus is a lieutenant-general invited to give a speech about his experiences in Iraq.
Ms. Broadwell made her dissertation topic a case study on Mr. Petraeus's leadership and secured his co-operation in 2008 after joining the general for a run along the Potomac River in Washington. She beat him.
The affair began two months after Mr. Petraeus became CIA director, according to friend and former official spokesman Steve Boylan.
"He regrets it on so many levels that I don't think anyone can really imagine how this has affected both his family and himself and, to some degree, the nation," a friend and former official spokesman said.