Remembrance Sunday services are to be held across the country in tribute to members of Britain's Armed Forces who have died in major conflicts.
The Queen will take part in a service at Whitehall's Cenotaph where she will lay a wreath in memory of those who paid the ultimate sacrifice.
The event is the focal point of the country's Remembrance Sunday ceremonies and will see other senior royals, Prime Minister David Cameron and opposition party leaders leave floral tributes at the memorial.
Lieutenant General Sir John Kiszely, the Royal British Legion's National President, said: "Remembrance Sunday is a time for the nation to unite in its reverence for the British Armed Forces past and present.
"When we bow our heads in reflection, we remember those who fought for our freedom during the two World Wars, but we also mourn and honour those who have lost their lives in more recent conflicts. Today, with troops on duty in Afghanistan and other trouble spots around the world, remembrance, and the two minute silence, are as important as ever."
The Queen will lay the first floral tribute followed by the Duke of Edinburgh, the Prince of Wales, Duke of Cambridge, the Duke of York, the Earl of Wessex, the Princess Royal and the Duke of Kent.
Next to pay their respects will be Mr Cameron, Liberal Democrat leader Nick Clegg, opposition leader Ed Miliband, leaders of other parties, High Commissioners from Commonwealth countries and defence chiefs. The ceremony is also attended by thousands of ex-service men and women who will stage a march past the Cenotaph.
At Saturday night's annual Festival of Remembrance in London the Queen and senior members of the Royal Family joined an audience of veterans and their families to honour Britain's war dead at the Royal Albert Hall.
The evening was hosted by the Royal British Legion and was both a moving tribute to the fallen and a celebration of their memory through music and song. X Factor star Joe McElderry, singer Katherine Jenkins and Sir Cliff Richard performed at the Festival.
The televised event included a performance by a choir whose members all have partners serving in Afghanistan. The Military Wives Choir from the Royal Marines Base Chivenor in north Devon sang Wherever you Are. The women have been led by choirmaster Gareth Malone who formed the group for his BBC Two television series The Choir.