The Queen led the tributes to Britain's war dead at the Cenotaph in London on Remembrance Sunday.
The Queen laid a wreath along with other Royals and MPs
Following a two-minute silence, the Queen laid a poppy wreath in memory of the dead, including 21 troops killed in Iraq this year.
Her grandson Prince William took part in the National Service of Remembrance for the first time.
Political leaders, including Tony Blair, joined some 9,000 veterans from 20th century conflicts at the event.
The Queen, dressed in black, emerged from the old Home Office building in Whitehall just before 11am and took up her position facing the Cenotaph.
At the first stoke of Big Ben at 1100GMT, a single round was fired from a field gun to signal the start of a two-minute silence.
The boom of a second round of cannon fire, from the King's Troop Royal Horse Artillery positioned on Horse Guards Parade, broke the silence.
The Prince of Wales, who is 56 on Sunday, laid a poppy wreath, along with the Queen, the Duke of Edinburgh, the Duke of York, the Princess Royal and Duke of Kent.
Mr Blair and other political leaders, including for the first time Northern Ireland's Rev Dr Ian Paisley, then laid wreaths, followed by Commonwealth High
Commissioners and military top brass.
When all the wreaths had been laid, there was a short religious service conducted by Bishop of London Richard Chartres.
Prince William, with Sophie, Countess of Wessex, was watching the wreath-laying and march past from a first-floor balcony in the Foreign Office, overlooking Whitehall.
The Normandy veterans led the march as the military mass bands played the March of the Veterans of Normandy.
Representatives of the War Widows' Association marched with the ex-service contingent.
As well as the 9,000 veterans marching or taking part in wheelchairs, some 1,500 civilians were also on parade.
And the Princess Royal, who is Commandant-in-Chief of the Women's Royal Naval Services, took the salute at Horse Guards of the columns of ex-servicemen and women taking part in the traditional march pass.
Across the rest of the UK, cities and towns held their own services.
Prince Edward led the laying of the wreaths in Edinburgh.
First Minister Jack McConnell said it was important to honour those who had made the ultimate sacrifice.
In Northern Ireland the main service was held in City Hall in Belfast.
Almost 50,000 people from Ireland died in the First World War.
In Llandudno, north Wales, the brother of Llywelyn Evans, the first Welsh solder to die in the Iraq war, laid a wreath.