''FORTUNATELY, history is not made up of daily headlines, blogs on websites, or the latest sensational attack," Donald Rumsfeld wrote in a Washington Post op-ed column last week. ''History is a bigger picture, and it takes some time and perspective to measure accurately."

Rumsfeld was arguing that any evaluation of the present catastrophe in Iraq should take a longer view, and I agree with him. Indeed, I have spent the last six years exploring two generations' worth of events and decisions that brought us here. I have written a long history of the Pentagon called ''House of War," which will be published in May. But contrary to what Rumsfeld hopes, such a ''bigger picture" in no way exonerates him or the Bush administration for its grave failures. The disaster in Iraq both recapitulates American mistakes of the past and worsens them immeasurably.