Together, the emphasis on transition and elections effectively armed one side in a violent communal struggle. A low-grade, tit-for-tat civil war between Sunni insurgents and Shia militias was thus well under way when the February 2006 bombing of the Golden Shrine in Samarra by AQI-one of the holiest sites in Shia Islam-tipped the country into all-out sectarian warfare. After that, Shia militias went on a rampage and set about systematically cleansing Baghdad of Sunni. The newly formed "unity" government led by Prime Minister Nouri al-Maliki was beholden to both the Sadrists and the Supreme Council for the Islamic Revolution in Iraq (SCIRI), and therefore did little to reign in the militias. The isf proved incapable and unwilling to quell the violence, and, in some areas, were perpetrators. In this landscape, Filkins writes,

there were Shiite police killing Sunni insurgents, Sunni police killing Shiite politicians. The Americans lost track. The Iraqis lost track. . . . So many groups and so many guns and so many uniforms. So many patches. It was like the final scene in "The Sneetches," the Dr. Seuss story that ends in a frenzy of Sneetches having stars planted and removed from their chests. At the end of the story, none of the Sneetches could remember who had had a star in the first place.

Neither could the Americans. All they had were the bodies.

LIKE MOST book-length accounts of the Iraq War, Filkins's text ends in 2006. Into this narrative void steps Linda Robinson, a reporter for U.S. News and World Report, who chronicles the origins and effects of the surge in Tell Me How This Ends. Robinson's account draws on extensive interviews with administration officials and senior military commanders, as well as reporting from some of Baghdad's most dangerous neighborhoods. If the book has a flaw it is perhaps that it relies too much on interviews with General Petraeus and his inner circle, at times giving it the feel of an official history. As such, it will not be the final word on this important period of the war, but is nevertheless an excellent early entry.

As Robinson documents, the surge emerged out of a critique of ongoing military operations in Iraq. In many respects, the story begins in November 2005, when the White House released the "National Strategy for Victory in Iraq" (NSVI). Written two-and-a-half years into the conflict, it was the first public statement outlining the administration's road map to success. The "security track" in the NSVI recognized the critical importance of population security and called for U.S. forces to employ a "clear, hold, and build" model. But there remained a substantial mismatch between the administration's stated strategy and the war on the ground. Applying clear-hold-build in Baghdad (let alone the rest of Iraq) would require substantial numbers of American troops-troops that President Bush, Secretary of Defense Donald Rumsfeld and the Joint Chiefs of Staff remained reluctant to send. General Casey, General John Abizaid (Casey's immediate superior) and Secretary Rumsfeld all believed that a large-scale U.S. military commitment fostered a dangerous dependency among Iraqi security forces and was the primary source of the insurgency. Instead they consolidated U.S. forces on large outlying bases, and focused on rapidly handing over security responsibilities to the Iraqis as U.S. forces made plans to withdraw.

With a handful of important exceptions in the 2005-2006 period, the majority of U.S. military units did not employ the entire clear-hold-build package. Instead, they focused on "clearing" and occasionally short-term "building," but largely left it to Iraqi forces to "hold" areas and depended on civilian entities and the Iraqi government to provide long-term economic assistance.

As the violence in Baghdad escalated in 2006, Robinson notes, a discussion about U.S. strategy emerged within the NSC. The conclusion was that the current strategy had failed because the ISF and Iraqi government were not capable of executing the "hold" and "build" portions of the clear-hold-build model. Despite ad hoc strategic reviews at the Pentagon and NSC, the administration delayed a full-scale rethink until after the November congressional elections, so as not to provide Democratic critics of the war with extra ammunition. By December though, Bush sided with those calling for a troop surge and a fundamental change in strategy.

In January 2007, Bush announced he was sending five additional combat brigades to Baghdad and two Marine battalions to Anbar Province. These forces were supposed to partner with the Iraqi Army and police to provide population security, tamp down sectarian and insurgent violence, and thereby provide "breathing space" for political compromises among Iraq's warring factions. Bush also announced that General David Petraeus would replace Casey and implement the new strategy.

Most of Robinson's book recounts what happened next. In 2006, Petraeus had championed an effort to fundamentally rewrite U.S. counterinsurgency doctrine. And, upon his arrival in Baghdad in February 2007, Petraeus and a brain trust of advisors produced a major revision of the "Joint Campaign Plan" guiding U.S. actions in Iraq. The new plan, completed in late May, framed the war as a communal struggle for power and security rather than simply an insurgency. It envisioned the surged troop levels-and a new push on the political and economic fronts-as prerequisites for population security, political accommodation and a bridging strategy after which the United States would once again move toward a transition to an Iraqi lead in security operations. It also recognized that there were too few U.S. troops to police the whole country, and so called for engaging "reconcilable" combatants to forge accommodation from the bottom up.

THE SURGE coincided with a huge improvement in the security situation, as attacks against Iraqi civilians and coalition forces declined dramatically, but whether or not it was the cause is up for debate. The significant increase in U.S. forces in Baghdad and surrounding areas, coupled with much-improved counterinsurgency practices and a growing ISF capability to hold cleared areas, was certainly one critical factor. Particularly important, according to Robinson, was the decision by U.S. commanders to establish dozens of combat outposts and Joint Security Stations to partner with the ISF deep within communities ravaged by insurgent and sectarian strife. Perhaps the best chapters in Robinson's book chronicle in great detail the heroic efforts of U.S. forces to tame violence in two of Baghdad's toughest neighborhoods.

But the most decisive reason for improved security was the Sunni Awakening: the successful effort to recruit Sunni tribes and former insurgents to cooperate with U.S. forces against AQI. The Awakening began in late 2006, when a group of tribal sheikhs revolted against AQI atrocities, power grabs and encroachments into tribal economic activities. So, the movement predated the surge and was spurred, in part, by increasing concerns that U.S. forces might withdraw and leave Sunni vulnerable to AQI and Shia militias. The end result was a dramatic reduction in violence in Anbar, once the hotbed of the Sunni insurgency.

Nevertheless, Robinson details how the surge helped spread the Awakening outward from Anbar to Baghdad. "The insurgents," she writes, "made the decision to stop fighting. But the U.S. troops' measures played an important part by setting the conditions for the volunteers to come forward. They would not have done so, at least in such numbers, had the U.S. soldiers not been out meeting with sheikhs, imams, and other intermediaries." The real cause, however, was not the additional troops per se, but rather a change in strategy. During the summer of 2007, General Petraeus and Lieutenant General Raymond Odierno encouraged commanders to apply the Anbar model elsewhere by striking financial deals and forging cease-fires with Sunni combatants. The effort quickly spread in greater Baghdad and elsewhere, contributing to the rapid growth of the so-called Sons of Iraq (SOIs). By mid-2008, approximately one hundred thousand individuals, 80 percent of them Sunni, were collecting a monthly stipend from U.S. forces to man checkpoints and patrol neighborhoods.

Also crucial to improving security was Sadr's decision to rein in his militia. In Karbala in August 2007, a ferocious gun battle erupted between JAM and the Badr Organization-a militia associated with the Islamic Supreme Council of Iraq (ISCI, the rebranded SCIRI party). The clash killed dozens and wounded hundreds. The following day, Sadr announced a six-month freeze on all armed actions by JAM. In February 2008, the truce was extended for another six months. Sadr undoubtedly sought to avoid a direct clash with U.S. forces at the peak of the surge. But his decision was also intended to improve JAM's image in the face of growing accusations of criminal behavior and to solidify control over his fractious organization. The fragile cease-fire temporarily collapsed this spring as a consequence of al-Maliki's decision to launch an offensive in Basra, resulting in an escalation of fighting between JAM and U.S. and Iraqi forces in both Basra and Sadr City. But, a pair of agreements-brokered, in part, by Iran-eventually helped calm the situation and reestablish the freeze on armed activities.

A final source of declining violence was the displacement of hundreds of thousands of Iraqis during the height of the civil war. The acceleration of sectarian cleansing in 2006 and early 2007 had the perverse effect of driving down subsequent attacks by exhausting combatants on both sides and segregating groups in Baghdad into defensible enclaves. And, as Robinson notes, these enclaves were then walled off from one another by concrete barriers erected by U.S. forces.