Washington ? A church sermon in Texas prodded George W. Bush toward the presidency, but he finally found his mission in the rubble of the World Trade Center.

Standing in the smoldering remains of the twin towers three days after terrorists destroyed them, Bush made a vow that transformed his presidency.

President Bush's presidency was transformed after the terror attacks, experts say.

“I can hear you,” he told rescue workers who greeted him with chants of “U.S.A.! U.S.A.!” “The rest of the world hears you. And the people who knocked these buildings down will hear all of us soon.”

The world now has some notion of what he meant, but it has yet to feel the full impact of his words. Convinced that history has handed him a mission, Bush has set out to eradicate terrorism wherever it hides, whatever the cost and no matter how long it takes.

“This is a time for self-defense,” he told his war council. “This is our time.”

The times have also changed Bush personally.

Always religious, the president turned more deeply to God. When audience members tell Bush he’s in their prayers, the president gets misty-eyed. He views the prayers as “the ultimate act of love,” Bush told one associate.

Associates say he has matured though he is still playful.

“War changes everyone involved,” said Ron Kaufman, political director for Bush’s father. “It changes not your values, but what you value. People call it maturity, but it’s something deeper than that. You’re dealing with life and death every day.”

In the days after the attacks, friends recall him tearing up as he talked about the attacks in private. Some say it was weeks before he had the time or temperament to start joking with them again.

Since the moment terrorists struck Sept. 11 and Chief of Staff Andrew Card whispered in his ear, “America is under attack” Bush has seen his presidency transformed.

“It has given the president a special mission, a special opportunity that comes to few presidents,” said Stephen Hess, a presidential analyst who worked in the Eisenhower and Nixon White Houses. “You can compare him to poor Bill Clinton, who hungered for a legacy more than any other but never got an opportunity.”

Unabashedly, White House officials point to America’s greatest wartime presidents Lincoln and Franklin D. Roosevelt as well as the Vietnam-scarred Johnson presidency to put Bush’s mission in historical context.

“Every president has an agenda, but they are always subject to the whims of history,” senior adviser Karl Rove said.

“The times place demands on them; they give them war, recession and strife or they give them quietude.

“This is what history’s given him,” Rove said.

“It’s a tough time to be president of the United States,” said Republican consultant Ed Gillespie, a former campaign adviser. “There are a lot of challenges before us.”

Bush, however, says he is undaunted.

“There’s a long way to go. We’ve got a lot of work to do,” Bush told a crowd in New Mexico recently. “I understand history has put the spotlight on this country. And so long as I’m the president, this country isn’t going to blink, we’re going to lead.”