What are the lessons of the Iraq War? In the midst of the coronavirus pandemic and widespread civil unrest, that question seems as distant and of as limited relevance to current public policy as a debate among historians about the causes of the First Crusade in the 11^th century. At some point, however, the United States will have to grapple with the recurrent questions of whether, when, and how to use military force under conditions in which, unlike those of today, force has a chance of achieving national goals. In those temporarily suspended but certain-to-return circumstances, the Iraq War and its legacy will once again command the nation’s attention.

The passage of time—it was 17 years ago in April that President George W. Bush dispatched American troops to Iraq to unseat its dictator Saddam Hussein—affords the basis for some historical perspective on the conflict that followed, making it possible to separate what is significant from what is marginal and to distinguish the enduring from the ephemeral. The publication of a compelling new book—The Great Rift: Dick Cheney, Colin Powell, and the Broken Friendship that Defined an Era by James Mann, the author of several excellent studies of American politics and foreign policy—provides an opportunity to revisit the issues at the heart of that war.

The book records the rise and fall of the friendship of two of the central figures of that era: Vice President Cheney, a strong advocate of deposing Saddam, and Secretary of State Powell, who expressed serious reservations about the wisdom of doing so but never explicitly opposed the war. What had been an effective partnership between the two foundered on their disagreements about Iraq policy.

Much of the book describes the workings of the George W. Bush administration and makes clear that on Iraq it did not function smoothly. The procedure for deciding whether to go to war did not merely lack rigor: It was all but nonexistent. Mann’s account confirms Richard Haass’s observation that the choice for war was “not a decision that was made so much as it ‘happened.’” Nor did the upper echelons of the American government engage in serious planning for postwar Iraq. When Saddam was defeated and the United States found itself responsible for governing the country, the Bush Administration had to improvise. Even when it settled on governing arrangements, moreover, its senior officials, including both Cheney and Powell, bickered over specific policies in ways that made the overall effort less effective than it might otherwise have been.

Still, in government as in other areas of human endeavor, procedure isn’t everything. Franklin D. Roosevelt often conducted his presidency in an erratic, secretive fashion, and yet he managed to implement the New Deal and to preside over victory in World War II. On the other hand, as demonstrated by the classic study by Leslie H. Gelb and Richard K. Betts of the performance of the American government during the Vietnam War—The Irony of Vietnam: The System Worked, whose argument is expressed in its subtitle—policy failure does not necessarily stem from procedural malfunction.

In Iraq, two major mistakes of policy rather than procedure contributed to what was for the United States an unsuccessful outcome. First, the Bush Administration greatly overestimated the threat that terrorism posed to American interests and to the United States itself. Senior officials, Cheney prominently among them, conceived of it as a challenge comparable in magnitude to those the country had faced in the 20^th century from fascism and communism. The Iraq war came about, among other reasons, because these officials concluded that a sharper, larger response than merely chasing the Taliban out of Afghanistan was needed to the terrorist attacks of September 11, 2001.

In the immediate aftermath of those attacks it was perhaps inevitable for them to arrive at such a conclusion. Over time, however, it became clear that terrorism did not pose an existential threat to the United States. It was, and is, a chronic, annoying, but ultimately manageable problem. The war to remove Saddam Hussein may have increased rather than reduced the number of anti-American terrorists worldwide and, as John Mueller has persuasively argued, the United States has surely spent more than was necessary on the domestic front of the war on terror.

In addition, the Bush Administration overestimated the feasibility of the mission that the occupation of Iraq involved: nation-building. The United States attempted to give the country it was occupying a stable, democratic political system and a working free-market economy. These efforts came up short at best. The reasons had less to do with the inadequacy of the American approach—although in retrospect it seems far from flawless—than with the inherent difficulty of the task. Democratic politics and free-market economics require a particular set of values, historical experiences, skills, and institutions that Iraq conspicuously lacked. Nor can these be imported and implanted by outsiders, no matter how powerful. They must be home-grown, which takes time—generations rather than months or even years.

Indeed, the failure to transform Iraq, as well as similar post-Cold War failures in Somalia, Haiti, Bosnia, and Afghanistan, offer an even larger lesson about foreign policy, especially when contrasted with American policy during the Cold War. In that protracted conflict the United States successfully discouraged the Soviet Union from attempting to invade Western Europe. This policy of deterrence bought time for the Western Europeans to build, over the decades after 1945, free and prosperous societies. The powerfully attractive example that the countries of Western Europe set for the people living under communism did more than any other development to bring about the collapse of communist rule to the east. American foreign policy, that is, prevented a bad outcome so that favorable trends could flourish; but while the United States protected, it did not directly cause those favorable trends. (The American example did play an important role.)

In general, the instruments of American foreign policy—guns, money, and statements that imply that either or both will be brought into play—have their uses, but they cannot, in and of themselves, transform other countries to make them more like the United States. Such a transformation depends on the people of the other countries, as was the case in Iraq.

The war in Iraq lost favor with the American public for the same reason that the 20^th-century wars in Korea and Vietnam became unpopular: The costs of the war, measured in American casualties, exceeded what the public was willing to pay for the mission. Americans did not reject the Bush Administration’s goals for the war. Rather, they decided that the conflict had become too expensive to pursue them and punished the administration at the polls, electing a Democratic Congress in 2006 and an anti-war Democratic president in 2008.

The loss of public confidence affected both of The Rift’s protagonists, from which a final lesson of Iraq emerges, this one concerning political careers. Able public servants, each with a sterling record of accomplishment at the highest levels of the American government, both Cheney and Powell saw their power reduced and their reputations tarnished by the war. For all their differences, their common experience recalls a melancholy, but in these cases sadly appropriate, observation by the 20^th-century English politician Enoch Powell: “All political lives, unless they are cut off in midstream at a happy juncture, end in failure.”