WASHINGTON - In a cramped nuclear shelter deep beneath the White House, President Bush stared across a spare wooden table and told his national security team, "Get the troops ready."
Twelve hours after the terrorist strikes, moments after his nationally televised address, Bush was preparing for a war that would transform and define his presidency - with a historic mission, broad new presidential powers and a federal government overhauled to protect against terrorism.
"This is a time for self-defense," he told his war council. "This is our time."
The times have also changed Bush personally.
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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.
A longtime health nut, Bush intensified his exercise regime to burn off stress. Unconsciously, he may have been trying to prove himself disciplined enough to meet the extraordinary challenges, associates say.
The president is said to be more fatalistic about his own safety. Reminded recently that assassination is a constant threat, Bush shrugged and said, "It's not my job to worry about it."
Associates say he has matured and is more sober-minded - though he is still playful, sometimes silly.
"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.
"The events, I suppose, have hardened him," said Joe Allbaugh, director of the Federal Emergency Management Agency and a longtime Bush associate.
Though he has always had swagger, Bush gained confidence in the past year. Critics call it arrogance; they point to his penchant for secrecy and a record of angering allies with unilateral foreign policies.
An effective delegator - critics call him lazy and out of touch - Bush began passing on even more chores after the attacks.
"He had to delegate issues that might have risen to him that now can be managed by others," White House chief of staff Andrew Card said.
Since the moment terrorists struck Sept. 11 - and 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.
History's gift to Bush was the opportunity to shed his image as an unprepared, narrowly elected president to a wartime leader with record-breaking popularity. For weeks after the attacks, he was politically untouchable.
As they rallied around the commander in chief, Americans hardly noticed domestic policies stalling.
Most jarring, Bush has overseen a huge explosion in government deficits, compared with surpluses during the Clinton years.
Bush's hoped-for Department of Homeland Security - with 170,000 employees - would lead to the largest government overhaul since President Truman revamped national security agencies.
Some analysts say Bush is overseeing the largest expansion of presidential powers since FDR's New Deal.
In addition to homeland security, he has proposed "first strike" powers for the U.S. military, refuses to seek a declaration of war from Congress and dramatically increased law enforcement powers.
Bush has recalibrated his foreign policy since Sept. 11.
A vocal opponent of "nation-building," he now promises to get the new Afghanistan government on its feet. Overthrowing Iraq's Saddam Hussein moved to the front burner.
Never a big advocate of foreign aid, Bush has proposed major increases in programs intended to eliminate breeding grounds for terrorism.
Paul Begala, a Democratic strategist, said voters retain doubts about Bush, even as they support him - an opinion privately shared among some White House aides and GOP strategists.
"We were pulling for him then. And we're pulling for him now," he said. "But even the way we're pulling for him is a little patronizing. We've all given Bush a pass because we want to believe he's up to the job."