The Queen will lead a remembrance service in the capital today as she lays the first wreath on the Cenotaph at Whitehall.
The event is the focal point of the country's Remembrance Sunday ceremonies and will see other senior royals, Prime Minister David Cameron and London Mayor Boris Johnson also leaving floral tributes at the memorial.
After the wreath laying ceremony and two minute silence at 11am, more than 10,000 military veterans and civilians will march past the Cenotaph.
The Queen and the Duke of Edinburgh will attend the Royal British Legion Festival of Remembrance tonight as the nation begins three days of honouring fallen soldiers.
Other members of the Royal Family will also be present for the event at the Royal Albert Hall, which will feature performances from pop stars James Blunt - a former army officer - and Katie Melua, plus the tenor Alfie Boe and new group the Poppy Girls.
The audience of 4,000, including Legion supporters and military families, will be joined by an estimated 5.2 million viewers on television.
Prince Andrew, the Duke of York, was challenged by armed police in the gardens of Buckingham Palace and asked to verify his identity after an intruder broke in last week.
The Metropolitan Police confirmed that a man was ordered to verify his identity by two officers, with the Sunday Express claiming the 53 year old prince had been told to "put your hands up and get on the ground".
Andrew had earlier attended an engagement in Piccadilly supporting new business ventures.
"The man was satisfactorily identified. No weapons were drawn and no force was used," the police said in a statement.
Two days ago police arrested a man who had been found inside the palace on Monday evening. He was held on suspicion of burglary, trespass and criminal damage.
A second man was arrested outside the palace on suspicion of conspiracy to commit burglary. Both men have since been released on bail.