On May 29, 2003, 50 days after the fall of Baghdad, President Bush proclaimed a fresh victory for his administration in Iraq: Two small trailers captured by U.S. and Kurdish troops had turned out to be long-sought mobile "biological laboratories." He declared, "We have found the weapons of mass destruction."

The claim, repeated by top administration officials for months afterward, was hailed at the time as a vindication of the decision to go to war. But even as Bush spoke, U.S. intelligence officials possessed powerful evidence that it was not true.