His Majesty’s Wedding Day is observed in the United Kingdom every April 9, commemorating the marriage of King Charles III and Camilla Parker Bowles, which took place on April 9, 2005. This day is significant as it is a designated flag flying day, during which the Union Flag must be displayed on UK government buildings. The wedding was a civil ceremony held at Windsor Guildhall, with notable attendance from senior royal family members, although Queen Elizabeth II and Prince Philip did not attend. Following the ceremony, a religious service was held at St. George’s Chapel at Windsor Castle, where the Queen and Duke of Edinburgh were present. The anniversary has been recognized since 2023, replacing the previous royal wedding anniversary of Queen Elizabeth II and Prince Philip. Camilla adopted the title Duchess of Cornwall after the marriage and later became queen consort upon Charles's ascension to the throne in 2022.