SIMI VALLEY, Calif. — Former first lady Nancy Reagan was celebrated in a stately funeral Friday that evoked the majestic splendor of her eight years in the White House and a Washington era that she and her husband defined.

Political, business and Hollywood potentates, a thousand in all, came to pay their respects. Her eulogists spoke of her signature elegance, political influence and withering contempt for those who dared cross her. Most of all, they spoke of the Reagans’ marriage as both an abiding love affair and a partnership in power, with Mrs. Reagan serving as her husband’s chief protector and a leading architect of his legacy.

“My life began when I met my husband,” Nancy Davis Reagan once said, and several mourners noted that the same may have been said of him.

The Reagans were “defined by their love for each other,” said former secretary of state James A. Baker III, speaking in a tent erected on the south lawn of the Reagan Presidential Library high on a hill facing the Topatopa Mountains. “Without her, he wouldn’t have been president.”

Their son agreed. “There likely wouldn’t have been a President Ronald Reagan without a Nancy Reagan,” said Ronald Prescott Reagan of his mother, who died Sunday at 94 of congestive heart failure.

While her husband was alive, Mrs. Reagan kept watch over every aspect of his life. Willing to play the heavy and often acknowledged by her husband and his key aides as a the sharper assessor of loyalty and character, she became a polarizing figure in national politics.

“Her determination was ferocious,” said their daughter Patti Davis, remembering a conversation they had when her mother was personally lobbying members of Congress to approve stem-cell research into Alzheimer’s disease, against the Republican Party position. “Even God might not have the guts to argue with Nancy Reagan.”

The couple’s love story was the theme of the 90-minute service, much of it planned meticulously by Mrs. Reagan, and theirs was a compact that could feel exclusionary even to those closest to them.

“My parents were two halves of a circle. Nobody truly crossed the boundaries of the exquisite space that was theirs,” Davis said. But so visceral was the former first lady’s love for her father, Davis said, that her mother felt both haunted and comforted for weeks after his death — hearing his footsteps down the hall, seeing him at the foot of her bed. She described “the circle of their own private world — indestructible, impenetrable, an island for two.”

Yet a remarkable collection of people were invited to hear the narrative of that world, including representatives of 10 White House families. Shortly before the funeral began in a history-filled first row, former first lady Hillary Clinton and Caroline Kennedy, the U.S. ambassador to Japan, helped frail former first lady Rosalynn Carter secure her seat between them.

Listed on the guest rolls as “Mrs. Bill Clinton,” perhaps in keeping with the social directives of an earlier age, the Democratic presidential candidate and former secretary of state took time from her frenetic campaign schedule to attend the ceremony. Sitting with her were first lady Michelle Obama; former president George W. Bush and his wife, Laura; Tricia Nixon; and Lynda Byrd Johnson Robb and Luci Baines Johnson.

Much of the guest list harkened back to the ’80s, the Reagan decade, including Wayne Newton, Anjelica Huston, Tina Sinatra, Bo Derek (“we shared horse stories”) and Ralph Lauren. Mr. T — a stalwart ally in Mrs. Reagan’s “Just Say No” anti-drug campaign (she famously sat on his lap at a Christmas event) arrived through a side entrance dressed in full camouflage attire, combat boots and an American flag wrapped around his head.

“Theirs was a love story for the ages,” said Brian Mulroney, who served as Canada’s prime minister when Reagan was president. “They had a magnificent sense of occasion. They had style, and they had grace, and they had class.”

In one of the service’s most poignant moments, Mulroney read a 1981 love letter that Ronald Reagan wrote to his wife for their first Christmas in the White House. The president wrote love letters to her regularly, hiding them around the house, which she collected in a shopping bag kept in her closet.

“For there could be no life for me without you,” the letter read. “I love the whole gang of you — Mommy, First Lady, the sentimental you, the fun you and the peewee powerhouse you. Merry Christmas you all — with all my love. Lucky me.”

Mrs. Reagan’s funeral brought together under one immense tent notable Democrats and Republicans at a deeply divisive time — from Newt Gingrich and former California governor Arnold Schwarzenegger to House Minority Leader Nancy Pelosi. Television producer Norman Lear, a major funder of liberal causes, recalled that “she had a civility and appreciation for other people’s points of view.” Also, that Mrs. Reagan “danced well.”

“One of the last great grande dames,” said television host Melissa Rivers, who recalled the countless conversations between Mrs. Reagan and her fashion maven mother Joan Rivers. “She was an elegant, wonderful woman.”

“I probably didn’t call her enough,” said actor Tom Selleck. Mr. T was overheard saying, “I don’t want to talk to the media out of respect for Mrs. Reagan.” Over the weekend, he tweeted: “That was the highlight of my career to be asked to work with the First Family on such a great cause. . . . I will never forget her . . . I will continue her work in trying to keep kids from the Dangers of Drugs.”

The service reflected her sense of unapologetically old-world elegance but also revealed the more playful side of Mrs. Reagan, a woman known for her steely reserve. She enjoyed the company of dashing men — like Selleck, Warren Beatty, her husband — and a delight for gossip. “She told wicked stories of old Hollywood,” Diane Sawyer observed.

The music was gorgeous, the setting full of sunshine and the budding greenery of spring, until the skies opened up with pelting rain as the ceremony concluded. Pallbearers included Mrs. Reagan’s brother, Richard Davis, columnist George Will, and Washington Post publisher and chief executive Frederick J. Ryan Jr., who serves as board chairman of the Ronald Reagan Presidential Foundation. Her mahogany coffin was made by Marsellus Casket Co. in Syracuse, N.Y., similar to the one she selected for her husband.

At the end of all the pomp and tributes Friday, Mrs. Reagan was to be laid to rest next to her husband on a hillside tomb on the library grounds facing the Pacific Ocean. “We think of Nancy reunited finally with her beloved Ronnie,” Mulroney said.

She had one final instruction.

“Don’t say I was tough,” she told her longtime friend and biographer Bob Colacello. “I was strong. I had to be, because Ronnie liked everybody and sometimes didn’t see or refused to see what the people around him were really up to. But everything I did, I did for Ronnie. I did for love.”

Wan reported from Washington.

Related:

Program for Nancy Reagan’s funeral in California

Before she was first lady: Nancy Reagan’s acting career

Nancy and Ronald Reagan, inseparable in life, together again

Meet the astrologer who brought the cosmos into the Reagan White House