Prince George and Princess Charlotte attended their great-grandmother Queen Elizabeth II's funeral on Monday, Sept. 19.
Two of the three children of William and Catherine, the Prince and Princess of Wales, were seen inside a car and later walking inside Westminster Abbey during the service.
William and the former Kate Middleton's other child, Prince Louis, was not in attendance.
World leaders from more than a dozen countries also attended Elizabeth's funeral, including President Joe Biden and first lady Jill Biden, French President Emmanuel Macron, New Zealand's Prime Minister Jacinda Ardern, Australian Prime Minister Anthony Albanese and Canadian Prime Minister Justin Trudeau.
Elizabeth, Britain's longest-serving monarch, died on Sept. 8 at her beloved Balmoral Castle in the Scottish Highlands at age 96. The United Kingdom has spent more than 10 days mourning her death, with her coffin spending several days in Scotland before traveling by train to Britain.
Elizabeth's eldest son, Charles, became king after her death. In his first address as monarch, he shared his love for Prince Harry and Meghan, Duchess of Sussex, and unveiled new titles for William and Kate, who were formerly known as the Duke and Duchess of Cambridge.
William and Harry were among the members of the royal family who received the queen's coffin on Sept. 13 when it arrived at Buckingham Palace.
The pair walked behind the queen's four children, King Charles III, Princess Anne, Prince Andrew and Prince Edward, on Sept. 14 as the coffin traveled from Buckingham Palace to Westminster Hall, where it stayed to lie in state for several days to allow the British public to pay their respects before the funeral.
William told a group gathered outside of the royal estate of Sandringham on Sept. 15 that the walk was "challenging" and that it "brought back a few memories." Many were reminded of the two brothers walking side by side during the same walk for the funeral procession for their mother, Princess Diana, 25 years ago.
Kate and Camilla, the queen consort, followed behind the procession in a car, while Meghan and Sophie, Countess of Wessex, traveled in a separate vehicle.
Over the weekend, the line to pay respects to the queen meant at least a 24-hour wait, according to the British Department for Digital, Culture, Media and Sport.
William and Harry stood vigil before the queen's coffin for 15 minutes, one day after Elizabeth's four children also stood vigil. Both Andrew and Harry were permitted to wear their military uniforms at the vigils despite being nonworking royals and previously not wearing them.
Following the funeral, Elizabeth's coffin will go to Wellington Arch in Hyde Park before it heads to Windsor Castle, her final resting place. She will be buried next to her husband, Prince Philip, who died on April 9, 2021.