As we assess the Iraq war, one observation is painfully inescapable: almost all the original planning was sadly misjudged. The war planners were wrong about the WMD, about the numbers of troops required, about the cost, about the reactions of the Iraqis themselves.
They combined their error with crushing, emphatic certainty. When Army Chief of Staff Eric Shinseki warned that more troops would be needed, he was slapped down by his civilian superiors. When White House economics adviser Larry Lindsey suggested a higher dollar estimate, he was publicly mocked by Secretary of Defense Donald Rumsfeld.
The errors arose from political necessity. The Iraq war resolution was passed by the House by a vote of 296-133 and the Senate by a margin of 77-23. But while support for the war was broad, it was also shallow. Members of Congress, public opinion - and I myself - were all over-influenced by the recent Serbian and Afghanistan experiences, which seemed to promise that bad regimes could be toppled rapidly and easily by remote weapons.
Had the president asked Congress for a trillion dollars to fight a war that would last seven years, Congress would have recoiled in appalled dismay.
Politicians are often accused of saying things they don't believe. That happens less often than you may suppose. What happens more often is that they say what they believe - but they happen to believe what they need to believe. So it was with Iraq. President Bush and his inner advisers believed what they needed to believe.
How could they have been so cocksure in the face of so much contrary opinion from seemingly well qualified people? They had good reason for their self-confidence. Over the previous quarter century, the group around George W. Bush - famously nick-named "the Vulcans" - had joined battles over the Cold War and over the Gulf War against many of the same people who would later oppose the Iraq War. The Vulcans had proved right; their opponents had proved wrong.
And those of us who followed and supported the Vulcans fully expected that history would repeat itself in Iraq: boldness would win.