The violence in Iraq, which was peaking in almost every category in the first months of 2007, steadily dropped after that. That decline was true across the board, including attacks by insurgents, civilian deaths, U.S. soldiers killed, Iraq security forces killed, car-bomb attacks and IED explosions.

In December 2006 the U.S. military map of "ethno-sectarian" violence in Baghdad was colored mostly yellow, orange and red, indicating medium to intense violence. The same map two years later was mostly colored green, indicating that the sectarian violence in Baghdad had largely subsided.

Of course, not all of this was due to the generalship of Petraeus. Other important factors such as the tribal revolt against al Qaeda's Iraqi affiliate worked in Petraeus' favor.

The Sunni Awakening movement had begun in 2006 before Petraeus arrived in Iraq, but he and his top commanders deftly managed it.

The tribal fighters of the Awakening movement ended up on the American payroll in the "Sons of Iraq" program, which by the spring of 2009 had grown to around 100,000 men. Many of those men had once been shooting at Americans; now they were shooting at al Qaeda.

Iraq today remains a dangerous place, but it is not in the grip of a civil war, and political differences are more likely to be decided by parliamentary maneuvers than by violence.

Certainly, Petraeus can claim a large share in the achievement of that outcome.

Petraeus was later tapped to try to turn around another war that wasn't going well, this time it was the war in Afghanistan and the call came from President Obama in 2010.

The jury is still out on what level of success Petraeus achieved during his tenure as the commander of U.S. and other NATO troops in Afghanistan.

As a result of the operations resulting from the "surge" of 30,000 U.S. troops into Afghanistan authorized by Obama and led in its latter stages by Petraeus, longtime Taliban havens in the southern Afghan provinces of Helmand and Kandahar have now been eliminated.

Special operations forces also have decimated the ranks of mid-level Taliban commanders to such a degree that last year the average age of Taliban commanders dropped from 35 to 25, according to U.S. military sources.

That said, the increased military pressure on the Taliban did not bring them to the negotiating table in any meaningful way as had once been hoped. And the Taliban continue to control many rural areas of the country.

Arriving at any judgment of Petraeus' record at the CIA is complicated by the fact that he was there for only around a year and, of course, most of the activities of the CIA are secret.

Some light will be shed on the agency's recent activity when the acting director of the CIA, Michael Morell, testifies next week before the Senate Intelligence Committee about the attack on the Benghazi consulate in September that killed four Americans, including the U.S. ambassador to Libya and two men who were recently revealed to be CIA employees.

It was Petraeus who was supposed to be delivering that testimony.

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