The Queen and other members of the Royal Family will attend the annual Royal Festival of Remembrance on Armistice Day.
This year the event at the Royal Albert Hall will mark the centenaries of women's service in the regular Armed Forces, the Battle of Passchendaele, the creation of the Commonwealth War Graves Commission and the 100th birthday of forces' sweetheart, Dame Vera Lynn.
It will also commemorate the 75th anniversary of the Battle of El Alamein and the creation of the RAF Regiment.
Other royals attending the service on Saturday include the Duke of Edinburgh, the Prince of Wales, the Duchess of Cornwall, and the Duchess of Cambridge who is pregnant with her third child.
They will be received by Jon Moynihan, president of the Royal Albert Hall, and Air Marshal David Walker, president of the Royal British Legion.
Other events taking place, as the UK marks Armistice Day, include an outdoor service of remembrance within the walls of the Armed Forces Memorial at the National Memorial Arboretum in Staffordshire.
The Western Front Association will also hold their annual service of remembrance at the Cenotaph in Whitehall on Saturday, where a two-minute silence will be held and wreaths laid.
On Sunday the Queen will watch from a balcony along with the Duke of Edinburgh as Charles lays a wreath on her behalf at the Cenotaph.
Charles will lead the nation in honouring the country's war dead in what is believed to be the first time the Queen has broken with tradition and not performed the symbolic duty when at the Whitehall service.
The change is seen as an example of the subtle shift of head of state duties from the 91-year-old sovereign to the heir to the throne.