ON THE morning of September 12th 2001, Americans woke up to a
changed country. They had seen the twin towers of the World
Trade Centre reduced to rubble, the Pentagon aflame and a field
in Pennsylvania transformed into a graveyard. Almost 3,000
people had been killed and twice as many injured, in the
bloodiest day on American soil since the battle of Antietam in
1862. They had seen their president—the most powerful man in the
world—flitting from pillar to post. And they had seen the face
of a new enemy. Before September 11th few people even in the
administration had heard of al-Qaeda. After that day there was
no getting away from the images of Osama bin Laden and his
agent, Mohammed Atta.  That September 11th changed America
dramatically is hardly open to debate: George Bush's presidency
has been about little else since then. But some of the changes
have been unexpected. Who would have guessed, as a shocked
country rallied round the flag, that five years later partisan
divisions would be deeper than ever? Who