Somehow, he's always there.

Billy Graham, America's most enduring evangelist, was summoned to the White House Wednesday, arriving roughly an hour and a half after the first squadron of fighter bombers took off from their base in Saudi Arabia. He stayed the night at the White House (a place so familiar he knows to ask for the Queen's Bedroom rather than suffer the rougher mattress of the Lincoln), quickly arranged with Christian military chaplains to hold a prayer service yesterday morning, and preached a 17-minute sermon to the assembled leaders of the country.

"This was supposed to be the Christian century," he told the audience of some 400 people, referring to religious predictions of a peaceful era. "But it has been anything but the Christian century. Why can't we settle our problems in peace?" But, he said, "there come times when we have to fight for peace.

"Our democracy has been built within the framework of the Ten Commandments and the Sermon on the Mount," he said. Perhaps, out of this war "will come a new peace and, as has been stated by the president, a new world order."

Graham reminded the audience, which included the president, vice president, their wives, military brass and most of the Cabinet, of difficulties faced by previous presidents, starting with George Washington, and quoted a prayer of Abraham Lincoln's "that we will be on God's side."

An Army chorus sang "God Bless America," and President Bush and the entire congregation joined in on "Amazing Grace." Graham then returned to the White House with the President for lunch before leaving Washington.

Graham, 72, has known George Bush for 30 years, introduced by Bush's father, Prescott, a Graham spokesman said. Graham and Bush and their wives have vacationed together in Mexico and at the Bush family home in Kennebunkport, Maine. Graham was the only clergyman at Bush's inauguration, giving both the invocation and the benediction. Although Bush is an Episcopalian and Graham a Baptist, they evidently enjoy each other's company to the extent that Graham told a fellow evangelist that "George Bush is the best friend he has in the whole world outside his own immediate staff," according to a 1988 book titled "George Bush: Man of Integrity," by Doug Wead.

If that is the case, it would merely underline Graham's role as unofficial chaplain to the White House, a series of unlikely symbiotic relationships that began with a visit to Harry S. Truman in 1950 that ended unpropitiously. The emerging young preacher arrived at the White House with three Billy Graham Team colleagues, all dressed in white suits and white buckskin shoes, and after a 20-minute chat asked to pray with the president. Graham's mistake, he said later, was to allow himself to be debriefed by waiting reporters, and to then reenact the prayer session for the cameras by kneeling on the White House lawn. He learned better.

Lyndon B. Johnson told one reporter that he summoned Graham whenever he needed some "good tall praying." Johnson would occasionally return the favor by appearing at a Billy Graham Crusade. Graham spent the last night of Johnson's presidency in the White House and stayed over for the first night of Richard Nixon's.

Jimmy Carter chaired one of the Graham crusades when he was governor of Georgia, and had hosted the reverend at his home, although Graham seemed a less visible presence during the Carter presidency. Dwight D. Eisenhower was the first president to actively befriend him, inviting him to the White House many times and on his deathbed asking to see Graham. John F. Kennedy invited him to play golf (Graham had to give up the sport for health reasons more than a decade ago), but the two were not close. Ronald Reagan, who came to power with the help of the conservative evangelicals from whom Graham gently distanced himself, was friendly but not a pal -- although he did make Graham one of his personal guests on Inauguration Day and awarded him the Medal of Freedom.

When Graham was hospitalized for thrombophlebitis in December 1976, three presidents called on one day to wish him well: the incumbent, Gerald Ford; the president-elect, Carter; and former president Richard Nixon.

It was Graham's relationship with Nixon, in fact, that has caused him the most difficulty and, according to some biographers, the most pain. A friend since their first golf game in 1952, Graham was shaken by the revelations of Watergate, and subsequently announced he was "out of politics," turning more toward social concerns such as poverty and the arms race.

In recent days, Bush has also consulted other clergymen, including the bishop of his own Episcopal church, Edmund Browning, who has led protests asking Bush not to use force in settling the Middle East crisis. On Monday, he talked by phone to Robert Schuller, the minister of Southern California's largest Protestant church, who came away with the feeling that Bush "didn't want his own way, he just wanted to make the right decision."

Schuller, the pastor of the Crystal Cathedral in Garden Grove and a well-known television evangelist, said Bush had called him on "a private matter" and that the two of them had then discussed the situation in the Persian Gulf.

"He said to tell the people that I'm praying, that I believe in prayer and really want their continued prayers," Schuller quoted Bush as saying.

But Graham seems to hold a special place in the White House, and it's hard to know why. By all accounts he is gregarious and genuinely decent, and has survived intact both IRS investigations and the religious scandals of recent years. Contributions to the Billy Graham Evangelistic Association were up to $71.6 million in 1989, according to the financial report released at the end of November, an increase over the previous year. Graham enjoys celebrities and is famous enough himself to be accepted on equal terms, always patriotically supportive of the nation's elected leaders.

Staff writer Lou Cannon and wires services contributed to this report.