By Sarah Bell
BBC News, Whitehall
Almost a million British soldiers died in World War I
Three of the last surviving veterans of World War I were greeted with a round of applause as they arrived to mark the 90th anniversary of the Armistice.
Henry Allingham, 112, Harry Patch, 110, and Bill Stone, 108, are among the last of the five million men and women who served in Britain's forces during the conflict.
The knowledge that this was almost certainly the last significant anniversary the men will attend made the event particularly poignant.
Watched by dignitaries including the Duchess of Gloucester, Prime Minister Gordon Brown and members of the Cabinet, the three men were led down Whitehall by a single piper shortly before 1100.
The veterans looked frail in their wheelchairs and were kept warm with tartan blankets on a bright but chilly winter day.
They were watched by serving officers from the Royal Navy, Army and RAF, whose uniforms created a sea of navy, khaki and RAF grey, punctuated with poppies and medals.
'The lucky ones'
There was a sombre silence as the wreaths were laid one by one by current servicemen on behalf on the men.
Marine Mkhuseil Jones, who has been awarded the Military Cross, laid a wreath for Mr Stone, saluting as he put it down, before returning and placing a hand on the veteran's shoulder.
Speaking before the ceremony about the war, and his friends who died, Mr Stone said: "I shall never forget it. I was one of the lucky ones and I'm thankful for that.
"Of course they should be remembered. If it wasn't for them we wouldn't be here."
He said he would spend the day "thinking of all those who are gone. We must not forget them".
Mr Patch closed his eyes after his wreath was laid by Lance Corporal Johnson Beharry, who was awarded the Victoria Cross during the Iraq conflict.
Mr Patch, the last known survivor of the Battle of Passchendaele in Ypres, said before the ceremony: "I am very happy to be here today. It is not just an honour for me but for an entire generation.
"It is important to remember the dead from both sides of the conflict. Irrespective of the uniforms we wore, we were all victims."
Mr Allingham, whose wreath was laid by Flight Lieutenant Michelle Goodman, who has the Distinguished Flying Cross, also said he was glad to attend the ceremony.
"It means a lot to me. I hope people realise what my pals sacrificed on their behalf," he said.
The three veterans then led a two-minute silence on the stroke of 1100 as the nation stopped to mark the moment - the 11th hour of the 11th day of the 11th month - in 1918 that the war ended.
There have been fears that once the veterans die, their stories may not live on. But the importance of Armistice Day was apparent to people of all ages in the crowd who spoke to the BBC News website.
Thousands of people gathered to watch the ceremomy
Michael Smallcombe spoke during the service about his grandfather William Smallcombe, who spent four years on the Somme with the British Army.
"Events like this are very important, " he said. "People should know what happened. It's very important for us to understand what they did, and why they did it."
Margaret Goddard attended the event with her four-year-old grandson, John Colling.
She said: "I wanted to bring him because I think it's important for younger people to understand what happened."
The continuing significance of the November ceremony was echoed by Poppy Appeal collector Vivienne Toole.
She said: "People have been wonderful, and I have been quite moved by things they have been saying and the amounts of money they have been putting in."
As the three WWI veterans left to enjoy the warmth of a reception in 10 Downing Street, it seems they can rest confident in the fact the memories of them and their comrades will live on.