President Bush sat at his desk in the Oval Office last night, holding in his hands the speech he would read in a minute's time to announce that the nation was at war. Spotting an aide in the audience, Bush pumped his left fist in a gesture of grim determination. "I feel good," he said.

Seconds later, Bush turned to the cameras and announced the war on Iraq, the first such "pre-emptive" war in U.S. history and the most fateful gesture to date of his presidency. Moments after the four-minute speech, Bush retired to the residence for the night. It all seemed oddly efficient.

For a White House that prides itself on discipline, yesterday was a demonstration that even war can be businesslike. The exact timing of the attack's start was, in fact, a last-minute decision. But the public rollout, expected for months and rehearsed for weeks, could only be described as orderly.

"This has been anticipated," a senior administration official said after Bush's speech, modestly understating the year of preparation that has gone into the attempt to oust Iraqi President Saddam Hussein. Although there was "some flexibility in the plans" among White House aides, "everyone was waiting for the predicted event to take place," the official said.

For months, as he wrangled with the United Nations, Bush spoke about the looming war with qualifiers such as "if force is necessary." Between 6:30 and 7:00 p.m. yesterday, Bush dropped all qualifiers. Then, midway through a 3-hour meeting in the Oval Office, after reviewing the latest intelligence reports, Bush directed his national security team to put in place its war-launch plans.

At about 7:20 p.m., Bush closed the meeting and left the Oval Office, met briefly with speechwriter Michael Gerson to go over the long-anticipated speech and sat down to dinner in the White House residence with first lady Laura Bush. As the couple dined, the orders to attack were already working their way through the military under the time line Bush and his national security team had prescribed.

At 8 p.m., the deadline under Bush's 48-hour ultimatum for Hussein to go into exile -- Chief of Staff Andrew H. Card Jr. called to say that, to nobody's surprise, there was no sign that Hussein had left Iraq. Bush stayed nearly two hours more in the residence, returning to the Oval Office just before 9:45, when press secretary Ari Fleischer stepped to the briefing room lectern to announce "the opening stages" of war and say the president would speak to the nation.

Bush's aides, jittery throughout the day, grew tense as the Oval Office speech approached. A young aide gave a stern lecture to cameramen who were about to photograph Bush, warning them not even to whisper and said that if they made noise, "You'll never shoot in the White House again."

Eschewing his usual blue tie for the more formal red, Bush rehearsed his speech for half an hour, then delivered it with furrowed brow. Over his shoulder, the presidential flag was draped in such a way that the quiver full of arrows could be seen in the eagle's clenched talon.

The speech done, the president quickly retired to the residence, while aides donned their coats and headed for the exits.

"That's it for tonight," one said to journalists pleading for more information. "I'm going home. We've got nothing for you tonight." At 10:30, a young press aide told an incredulous press corps that there was a "full lid" for the night -- White House jargon meaning there would be no more news until morning.

In the Bush White House, even war can be given a "full lid" at a decent hour. It was a fitting end to a day that gave a tight schedule even to something as inherently unpredictable as war.

Yesterday morning, Bush arrived in the Oval Office before 8 a.m., placing a congratulatory call to British Prime Minister Tony Blair, who won a vote in support of war in Parliament. Bush took his usual intelligence briefings, then walked downstairs to the underground Situation Room for his first of three National Security Council meetings. The session lasted three-quarters of an hour, followed by a session with Defense Secretary Donald H. Rumsfeld.

As White House staffers watched the clock move toward the 8 p.m. deadline, Bush worked on other matters, meeting with New York City Mayor Michael Bloomberg and Homeland Security Secretary Tom Ridge, and talking with aides about his energy policy, which suffered a defeat yesterday in the Senate.

At 3:40 p.m., Bush met for the third time with his National Security Council. This time, the meeting was an unscheduled one. The decision to launch the attack was kept secret even from relatively senior aides, several of whom believed well into the evening that it would not be last night. But as the meeting progressed, "it became clear to the White House staff outside that meeting what was going to happen," one official said.

After insisting for months that there had been no decision to go to war, Bush and his aides could now say that there was such a decision. After Bush left to return to the residence for the night, an official observed: "He's very comfortable with this."

President Bush's announcement of the commencement of bombing in Iraq culminated an orderly process that took months to unfold.