Harry, Meghan Become Husband, Wife in British Royal CeremonyBritain's Prince Harry, who is sixth in line to the throne, and American actress Meghan Markle married Saturday in a ceremony in Windsor, just outside London. Beneath cloudless skies, hundreds of thousands of people lined the streets of the historic town to catch a glimpse of the bride-to-be as she arrived at Windsor Castle in a Rolls-Royce Phantom. There were cheers from the crowd as she stepped onto the grounds of the castle's Saint George's Chapel, revealing for the first time her choice of wedding gown. The simple yet elegant pure white dress was designed by Clare Waight Keller, the first British designer for the French fashion house Givenchy. The sweeping 5-meter train was carried by 7-year-old pageboys John and Brian Mulroney, the twin sons of one of Meghan's best friends. The bride walked up part of the aisle by herself, before being met halfway by her now father-in-law Prince Charles, who led her to the altar to a waiting Prince Harry. Markle's father, Thomas, was too ill to attend the ceremony, having reportedly undergone heart surgery this week. In Photos: The Royal Wedding The Archbishop of Canterbury, Justin Welby, conducted the ceremony and proclaimed the royal couple husband and wife shortly after 12:30 local time. The Most Reverend Michael Curry, the head of U.S. Episcopalian Church, gave an address, beginning with a quote from civil rights leader Martin Luther King Jr.: "We must discover the redemptive power of love, and when we do that, we will make of this old world a new world." Soprano Elin Manahan Thomas sang during the service. The 600 guests included Meghan's mother, Doria Raglan; Hollywood actor George Clooney and his lawyer wife, Amal; talk-show host Oprah Winfrey; tennis star Serena Williams; David and Victoria Beckham; Sir Elton John and his husband, David Furnish; and several fellow members of the cast of Markle's former television program Suits, including her on-screen husband, Patrick J. Adams. Two of Prince Harry's former girlfriends, Cressida Bonas and Chelsy Davy, also attended. The newlyweds emerged onto the steps of St. George's Chapel and received a huge cheer as they kissed in front of the crowds. A horse-drawn carriage then took them through the streets of Windsor, delighting onlookers, many of whom had been camping out for days to secure the best spots. Many fans began chanting Meghan's name. "It was beautiful, to be part of history, to be part of history, to see that up close like that. She was absolutely radiant, she was sparkling. Harry just looked so happy — you could see the joy in his eyes. We were this close and it was just wonderful," said royals fan Lindsay Hainer. Queen Elizabeth bestowed new titles upon the royal couple. They will now be known as the Duke and Duchess of Sussex. In Photos: Crowds, Stars Gather for Royal Wedding The U.S. ambassador to Britain, Woody Johnson, took to Twitter to offer his congratulations, writing: "On behalf of all Americans, I want to wish HRH Prince Harry & Meghan Markle a very happy future as they begin married life together." Elton John performed at the reception in Windsor Castle, where the canapes included Scottish langoustines, British asparagus and Windsor lamb. The wedding cake was flavored with Italian Amalfi lemon curd and British elderflower buttercream. Hundreds of millions of people around the world were thought to have watched the ceremony unfold on television. Observers said there would be relief within the royal household that the ceremony went off without a hitch, following the uncertainty in the run-up to the big day over whether Markle's father would attend. Speaking to the celebrity news site TMZ from Mexico, Thomas Markle said after the ceremony, "My baby looks beautiful and she looks very happy." "I wish I were there and I wish them all my love and happiness," he added. The marriage of the new Duke and Duchess of Sussex marked a further modernization of the ancient British institution. In past generations, members of the royal family usually married other members of European aristocracy. The new duchess will receive plenty of help and training on how to get by in one of the most high-profile positions in global public life. Founder of the British Monarchist Society Thomas Mace-Archer-Mills said the former actress was well-prepared for life in the limelight: "The skills on screen will carry over to the royal stage. So when she's on parade with the rest of the royal family, she will have it down to a T." ​Both Harry and Meghan have voiced their desire to continue to work together on their shared passion for charity, particularly in Africa. First, though, comes the honeymoon, with much public speculation about their choice of destination. African countries topping the list of favorites included Botswana, Namibia and Malawi, while the new duchess was thought to be a fan of Italy, the Philippines and Turkey.