Historians will likely judge David Petraeus to be the most effective American military commander since Eisenhower.

He was, after all, the person who, more than any other, brought Iraq back from the brink of total disaster after he assumed command of U.S. forces there in 2007.

To understand how daunting a task that was, recall that when Petraeus took over in Iraq, the country was embroiled in a civil war so vicious that civilians were dying at the rate of 90 a day.

Iraq's government itself was fueling the violence because the Iraqi Ministry of the Interior was home to a number of Shia death squads.

Meanwhile, al Qaeda's brutal Iraqi affiliate was recruiting hundreds of suicide attackers from around the Middle East who went on to kill thousands in Iraq.

As a result of this mayhem, some 5 million Iraqis -- around a fifth of the population fled the country or went into internal exile.

After a 2003 tour in Iraq where Petraeus effectively pacified the area in and around Mosul in the north and a second tour where he had a less successful stint trying to reform the disbanded Iraqi army, he was assigned to run the U.S. Army's Combined Arms Center at Fort Leavenworth, Kansas, in 2006.

This was seen as something of a backwater for the rising star general who Newsweek had anointed with a cover story two years earlier headlined "Can This Man Save Iraq?"

But Petraeus saw his tour in Kansas as an opportunity to revamp the Army's counterinsurgency doctrine, something the military hadn't put any real thought into since the Vietnam War. And now it was a complex stew of Sunni and Shia insurgent groups that the U.S. military was fighting in Iraq.

So Petraeus turned his time in Kansas into a year-long exercise to rewrite the strategy and tactics of the Iraq War.

To help him, Petraeus recruited Iraq War veteran John Nagl, a Rhodes Scholar with a doctorate from Oxford who in 2002 published the book "Learning to Eat Soup with a Knife: Counterinsurgency Lessons from Malaya and Vietnam."

In November 2005, Petraeus gave a lunchtime speech at a counterinsurgency conference in Washington. Nagl recalls that Petraeus, his former history professor at West Point, "announced that he was going to write a counterinsurgency manual, and he announced that I was going to be the lead pen, which was the first time I'd heard of it."

Nagl assumed the role of managing editor of the manual and Petraeus recruited Conrad Crane, a military historian and a former West Point classmate, to be the lead writer. But there was no doubt who was in charge. Nagl recalls that Petraeus "was the driver, he was the vision, he was the copy editor, he read the whole thing twice, he turned around chapters in 24 hours with extensive edits and comments."

The writings of the French soldier-intellectual David Galula were quite influential on the group working on the manual. Galula had fought in Indochina and Algeria in the 1950s as an officer in the French army as it was attempting to stamp out nationalist insurgencies in its colonial possessions.

Around a decade later Galula published "Counterinsurgency Warfare: Theory and Practice," which distilled the lessons of fighting and observing insurgencies in the Middle East and Southeast Asia.

Galula laid down a general principle that is recognized as the core of a successful counterinsurgency strategy: "The population becomes the objective for the counterinsurgent as it was for his enemy."

This meant that seizing territory became far less important than it was in a conventional war; ensuring that people felt secure enough so they were not forced to have to side with the insurgents and, eventually, even felt secure enough to provide intelligence about them, became the prize.

Once a first draft of the counterinsurgency manual was completed, Petraeus and the lead writer, Crane, decided to convene a group of outside experts to critique it. Crane recalls, "We had a vetting conference to go over the doctrine, and I agreed with the general that we would do it, and I said, 'Yeah, let's bring in 30 smart people to talk about it'; he brought in 150. It was quite a three-ring circus out at Fort Leavenworth."

Over the course of two days officials from the CIA, State Department and leading academics and journalists such as Eliot Cohen, James Fallows and George Packer were instructed to give their critiques, which generated hundreds of pages of new ideas.

The army and Marines published the final version of the Counterinsurgency Field Manual in December 2006.

The doctrines in this new manual deeply informed how the U.S. military would fight the wars in Iraq and Afghanistan.

The manual pointed to such unsuccessful counterinsurgency practices as overemphasizing killing and capturing the enemy rather than making conditions secure for the populace, conducting large-scale operations as the norm and concentrating military forces in large bases for protection.

This was, in fact, a good description of what the U.S. military had been doing in Iraq for the past three years of the conflict and an explanation of why it was now losing the war.

Successful practices, the new manual emphasized, focused on meeting the needs and ensuring the security of the population.

In a section titled "Paradoxes" the manual made a number of recommendations that were hardly typical of prevailing U.S. military doctrine: "Sometimes doing nothing is the best reaction" and "the host nation doing something tolerably is normally better than U.S. doing it well."