WASHINGTON -- As the nation mourned, America's political leadership gathered at Washington's National Cathedral at noon yesterday: to pray, to remember, and to gird for the war to come.

"This nation is peaceful but fierce when stirred to anger," U.S. President George W. Bush told a nationally televised memorial service for those killed in Tuesday's air attacks on the World Trade Center and the Pentagon. "This conflict was begun in timing and terms of others. It will end in a way and at an hour of our choosing."

Former presidents Bill Clinton, George Bush, Jimmy Carter and Gerald Ford joined members of cabinet, Congress and representatives of the armed services in a ceremony of prayers, homilies and martial hymns.

There were elements of great poignancy to the service -- the readings from the Old and New testaments and the Koran; the congregation, in full voice, singing The Battle Hymn of the Republic, the tears of many who mourned as they worshipped.

There were moments of fell purpose. "Today we say to those who masterminded this cruel plot, and to those who carried it out, that the spirit of this nation will not be defeated by their twisted and diabolical schemes," Rev. Billy Graham, 83, declared in his sermon. "Some day, those responsible will be brought to justice."

But there was also a plea from Rev. Nathan Baxter, Dean of Washington National Cathedral, that "we not become the evil that we deplore."

Neither inside nor outside the cathedral, however, was there much of a spirit of forgiveness. George West, 31, was one of about 200 onlookers who gathered outside to watch the cavalcade of dignitaries, and to show support. Mr. West carried a sign: "Today we mourn, Tomorrow we avenge."

"After our mourning period is over we're going to unleash hell," he said. "I just hope that they can see the sign when they're coming through."

The service at National Cathedral was just one of hundreds in churches, mosques, synagogues and temples across the United States, after Mr. Bush asked all Americans to pause at noon to attend a memorial service.

At a morning service in Connecticut, Gov. John Rowland spoke of a Roman Catholic priest he knew who died on United Airlines Flight 175 from Boston to Los Angeles, which crashed into the Trade Center. If Mr. Grogan were still here, he would ask us to be "persuaded by our better natures," Mr. Rowland said.

In Providence, R.I., about 100 gathered at the Central Congregational Church. "If there can be any good that comes from this horrific tragedy, it's that we come together and put our differences aside," said Maura Mullaney of Providence. Members of the Islamic Center of Long Island, stunned by the many revenge assaults on Muslims, were planning to hold the second of three services for victims. They also will collect donations for the American Red Cross.

"We're hurting, too, and we're also Americans," said Arshad Majid, a member of the center. "There were Muslim lives lost in that building, as well. We're all human and we need to get together."