This article is part of the Foreign Affairs Iraq Retrospective.

Ten years ago this week, the United States and a few of its allies invaded Iraq, writing the final chapter in Washington’s checkered decades-long relationship with Saddam Hussein. Thanks to problems of both conception and execution, the Iraq war ended up becoming the most egregious failure in half a century of American foreign policy, costing a vast amount of blood and treasure for all concerned and tarnishing the United States’ reputation for international leadership, honesty, morality, and even basic competence.

A swift and successful invasion dissolved into chaos once Baghdad fell: liberation turned into occupation; local uncertainty turned into insurgency and then civil war. Four long years after the toppling of Saddam’s statue in Firdos Square, a new and better-resourced American strategy managed to build on some positive local trends and stabilize the situation, so that by the end of the decade Iraq had pulled back from the brink and gained a chance at a better future. But even then nothing was guaranteed, as low-level violence and political turmoil continued; the withdrawal of the last American troops in December 2011 left behind a deeply troubled country.

How could this happen? How could the strongest power in modern history, fighting a rematch against a much lesser opponent at a time and place of its own choosing, find itself yet again woefully unprepared for a war’s aftermath and stumble so badly as a result?

The perversity of such an outcome belies simple explanations, which is why neither the George W. Bush administration’s most passionate defenders nor its most passionate critics are good guides to the case. The problems that emerged after Saddam’s ouster cannot be written off as random acts of God. They were entirely predictable, and indeed were repeatedly predicted by many people inside and outside the U.S. government. This makes the failure to plan carefully for avoiding or at least mitigating them an act of gross negligence, whatever else about the war might have gone well. Yet the Bush administration itself was one of the casualties of its blunders: the mess in Iraq blackened the reputations of almost everybody involved, helped cost the president’s party control of Congress in 2006, and contributed to Bush’s leaving office with the lowest approval ratings in history. If it was all some nefarious self-interested conspiracy, it was a bafflingly inept one.

The true story is more complex, with several elements required to explain how events played out as they did. The decision to go to war was driven by the psychological impact of 9/11 on key administration officials, together with their pre-existing beliefs about the dangers that Saddam posed. The administration’s scorn for “nation-building,” meanwhile, led it to believe that postwar commitments could be kept limited without ill effect. A dysfunctional national security decision-making process allowed the operation to proceed without serious questioning of heroically optimistic assumptions or proper contingency planning. And the combination of American hegemony and the trauma of 9/11 removed any significant foreign or domestic check on the administration’s actions.

There were numerous points before and during the conflict at which U.S. policy could have been different, with potentially dramatic consequences. For example, the “surge” -- the new U.S. counterinsurgency strategy -- helped reverse the course of the war in 2007 and 2008. Might a similar approach embraced at the outset, securing and stabilizing the country right after the toppling of Saddam’s regime in April 2003, have forestalled or mitigated many of the problems that emerged? And going back further, if the Bush administration had squarely confronted the question of just how difficult it would be to midwife the birth of a new Iraq, and just how much time it actually had to deal with the problem, would it have chosen to invade so precipitously in the first place?

Historians will long debate these and other questions, with the perspective that hindsight and better information provide. We at Foreign Affairs were participating in the debates in real time, and it is appropriate to reflect on how we did. There were four main sets of questions surrounding the war: whether to launch it; how to handle the aftermath of the invasion; how to respond to the failure of the initial American postwar strategy; and how to handle the exit. In terms of offering readers a thorough airing of all significant arguments on all important issues, we did better on the last two sets of questions than we did on the first two -- in part because we were less imaginative than we should have been in considering the possibility that the U.S. government could act as recklessly and incompetently as it eventually did. We presented competing arguments for and against the war, along with some sensible advice on how to address foreseeable postwar problems. But we could have asked tougher questions earlier and more urgently.

On the tenth anniversary of the start of the war, we offer some of the highlights of our coverage. Kenneth Pollack’s “Next Stop Baghdad?” appeared in March/April 2002. The first serious case for a U.S. invasion of Iraq, it became the genesis for his later influential book The Gathering Storm. Fouad Ajami’s “Iraq and the Arabs’ Future” and Richard Betts’ “Suicide From Fear of Death?” appeared in January/February 2003, offering opposing views of the wisdom of the impending conflict.

Larry Diamond’s “What Went Wrong in Iraq,” an anguished memoir of his stint as an adviser to the Coalition Provisional Authority, came out in September/October 2004; it formed the kernel of his later book Squandered Victory. In early 2005, Edward Luttwak made the case for withdrawal in “Iraq: The Logic of Disengagement,” and later that year Andrew Krepinevich sketched out the merits of a counterinsurgency approach in “How to Win in Iraq,” helping to lay the intellectual groundwork for what would become the surge.

In the spring of 2006, we published “Saddam’s Delusions,” by Kevin Woods, James Lacey, and Williamson Murray -- a long essay based on the Iraqi Perspectives Project, the U.S. military’s effort to gather, translate, and learn from reams of captured Iraqi documents. It remains a landmark text for understanding the situation beyond the looking glass, on the Iraqi side.

As the war continued to spiral downward in 2006, we offered readers wide-ranging debates on how Washington should respond. Stephen Biddle’s “Seeing Baghdad, Thinking Saigon” explored the ramifications of understanding the conflict as a communal civil war rather than an insurgency. Two follow-on exchanges -- one with Biddle, Larry Diamond, James Dobbins, Chaim Kaufmann, and Leslie Gelb and the other with Biddle, Christopher Hitchens, Fred Kaplan, Marc Lynch, Kevin Drum, and Diamond -- thrashed out the problems and picked apart all manner of competing solutions.

The Bush administration’s implementation of the surge in 2007 changed the course of the war once again, solving some old problems while generating some new ones. Steven Simon’s critique “The Price of the Surge” took a skeptical view, with Colin Kahl and William Odom flanking his recommendations on either side in their responses. In early 2011, Emma Sky -- who had advised U.S. Iraq commander Raymond Odierno -- traced “Iraq, From Surge to Sovereignty.” And in early 2012, Ned Parker offered a compelling portrait of “The Iraq We Left Behind,” arguing depressingly that it might eventually become “the world’s next failed state.”

An earlier U.S. military fiasco, in Vietnam, also dominated headlines and convulsed the United States and a foreign region for more than a decade. But in the long run, it proved to be less geopolitically significant than either its proponents or its critics could ever have imagined -- a deeply unfortunate episode in Washington’s larger, more successful conduct of the Cold War. For all that the Iraq war was seen at the time as some sort of fulcrum of global history, it too may meet a similar fate, looming larger to contemporaries than it does in the larger history of the post-Cold War international order. But before it goes down the memory hole entirely, its mistakes bear mulling, lest they be repeated yet again, with comparable consequences.

This article is part of the Foreign Affairs Iraq Retrospective.