These days, you can almost hear this administration struggling to find its own combination of domestic and foreign programs — Supreme Court appointments and education initiatives, tinkering with domestic liberties in the name of facing down foreign enemies — that makes the difference between an FDR and a Franklin Pierce.

What if Iraq in a few years is a muddle of its own, neither a great democratic success nor the battleground of a sectarian civil war? Or if it takes decades to sort out? The history of American interventions is littered with such examples. In the Philippines, victory in 1898 was followed by more than a decade of insurgency, and democracy did not begin to take full root for nearly a century.

And is fighting Islamic radicalism really akin to fighting fascism and communism, as Bush insists?

Even some of Bush's aides wonder if, in a few years, the battle against al-Qaida might look more like the fight a century ago against anarchists who set off bombs and even managed to kill an American president and a host of European heads of state. Of course, those anarchists operated in a prenuclear age when only states could kill hundreds of thousands of people at a time. Bush argues, in effect, that he is the first president to reorient the country to face superempowered fanatics seeking weapons Hitler dreamed about and Stalin possessed.

So he may have the raw ingredients needed: a big idea, driven by a big event, 9/11. "One thing that makes for great legacies are great crises, and we have had that," said John Lewis Gaddis, the Yale historian who just published "The Cold War: A New History" (Penguin, 2005). "But it then requires not only the right diagnosis of the problem but a strategy that proves durable enough that it survives the end of the administration that invented it, and is picked up by subsequent administrations of either party."

The prime example comes, not surprisingly, from Truman's time: containment.

Over the years, with input from the likes of George Kennan, that strategy evolved to exploit the divisions behind the Iron Curtain. Gaddis said the White House is starting to do the same among the jihadist groups. "The question historians will be asking is whether the Bush people will have established a similarly durable legacy," he said.

Clear victory helps a legacy, too. The Cold War took decades. As Bush's poll numbers began to fall last year, his aides clearly decided he couldn't afford the wait. So they put "victory" backdrops behind the president, and for the first time he described what victory against a shadowy enemy might look like. It comes in three stages.