BOOK OF THE DAY: Tell Me How This Ends: General David Petraeus and the Search for a Way Out of IraqBy Linda Robinson Public Affairs 411pp, $27.95
GEN DAVID Petraeus was always an atypical soldier. A gung-ho overachiever, he married the superintendent's daughter at West Point and wrote his doctoral thesis at Princeton on the lessons of the Vietnam War. In Iraq when Saddam Hussein's regime fell in April 2003, Petraeus defied the dominant view that everything would fall into place, the troops would come home and Iraqis would live happily ever after. "Tell me how this ends," Petraeus kept saying.
Gifted with the 20/20 vision of hindsight, Linda Robinson identifies the criminal errors that led to the Iraq debacle. Scarce resources were wasted on the search for non-existent weapons of mass destruction. Then US secretary of defence Donald Rumsfeld deployed inadequate numbers of US troops. An obsession with troop levels and the trappings of democracy - elections, elections, elections - then blinded US policy-makers to the central, political problem: that Iraq's Sunnis, Shias and Kurds could not agree on who would wield power.
Petraeus clashed early with the book's principal scapegoat, the erstwhile American proconsul Paul Bremer, whose firing of all Baathist officials and civil servants and dissolution of the Iraqi armed forces helped create the insurgency. Bremer and the neoconservatives in the Bush administration favoured the majority Shia Muslims whom they'd "liberated" from Saddam, and shunned the Sunnis.
Rumsfeld refused to allow the word "insurgency" to be used around him. As for the Sunni-Shia conflict, hadn't the US freed the Iraqis from their dictator? Now let the Iraqis sort out their problem, Rumsfeld reasoned.
But by 2006 the bloodbath reached civil war proportions. One hundred and fifty bodies were being found on the streets of Baghdad each morning, as Sunni and Shia "ethnically cleansed" each other.
A small group of Bush advisers noticed that where US forces were present in sufficient numbers, violence decreased. "The surgios" prevailed over US generals Casey and Abizaid, and the bipartisan Iraq Study Group, who recommended troop reductions. Bush approved plans for a "surge" of 30,000 US soldiers and in January 2007 appointed Petraeus as top US commander in Iraq.
Under the new Baghdad security plan, the extra soldiers were dispatched to the most violent areas of the capital. Robinson recounts in terrifying detail attacks on US patrols in the Sunni area of Adhamiya, where 200lb bombs exploded under armoured vehicles, incinerating the US soldiers inside.
To isolate the al-Qaeda insurgents, Petraeus walled up entire neighbourhoods, searching everything that went in or out, turning Baghdad into a series of ghettos.
Petraeus's other innovation was the creation of the 90,000-strong Sunni militia known as Sons of Iraq, who are armed, trained and paid by US forces. Suddenly, the Sunnis saw the Americans as protectors, and attacks on US forces fell dramatically.
At the beginning of his Baghdad assignment, Petraeus evaluated his chances of success to be only one in six. Perhaps fortunately for the general, the end of the "surge" has coincided with his move to central command (Centcom).
Two questions now taunt the incoming Obama administration: can the security gains of the "surge" be sustained as troops are drawn down? Is it possible to achieve a legitimate Iraqi government, based on power-sharing between ethnic and religious groups?
Barack Obama has promised to remove all combat troops within 16 months. The commitment is ambiguous, since untold numbers of military advisers, guards and administrators will remain.
Unfortunately for Obama, the arguments against a US departure remain valid: neighbouring Iran will doubtless step into the vacuum; the US cannot afford to lose the world's third largest oil reserves; and conflict between Sunni and Shia risks drawing in neighbours, threatening a regional war. The US is damned if it stays, and damned if it leaves. No one, not even Petraeus, can tell us how this ends.
• Lara Marlowe is France Correspondent ofThe Irish Times . She covered the US invasion of Iraq and its aftermath for the paper