Four World War I veterans have laid wreaths at the Cenotaph in London to mark the 90th anniversary of Britain's declaration of war on Germany in 1914.
108-year-old Henry Allingham lays a wreath at the Cenotaph
The men - all aged over 100 - also read poems and prayers at the ceremony.
They were accompanied by deputy prime minister John Prescott, veterans minister Ivor Caplin and Commonwealth high commissioners to London.
Mr Prescott and Mr Caplin also laid wreaths on behalf of the Queen, the government and the Commonwealth.
Veterans Henry Allingham, 108, from Eastbourne, East Sussex, William Stone, 103, from Watlington, Oxfordshire, John Oborne, 104, from Porthcawl, Bridgend, and Fred Lloyd, 106, from Uckfield, East Sussex took part in the ceremony.
The service started at 1100 BST, when Mr Allingham, Mr Oborne and Mr Lloyd were escorted in their wheelchairs from the Foreign Office to the Cenotaph by serving members of the Armed Forces.
Mr Stone walked behind his colleagues, as hundreds of people looked on.
WORLD WAR I FACTS
Some 900,000 soldiers from the British Empire died and two million were wounded during the war
British and German forces laid down their arms on Christmas Day 1914 for a game of football
In 1915 women took up men's jobs while they fought
The attack at Flers-Courcelette, at the Somme in 1916 saw the use of the first British tank
The Royal Family changed their name to Windsor from the German sounding Saxe-Coburg-Gotha in 1917
Over the course of the war Britain mobilised almost nine million soldiers
Following the lament of the Last Post and a minute's silence, the four men laid wreaths for those slain between 1914 and 1918.
Mr Allingham, Britain's oldest known surviving World War I veteran, struggled free of his wheelchair and bent down in front of the Cenotaph unaided to lay his wreath.
Mr Stone led the service by delivering the exhortation before Mr Allingham and Mr Oborne read the Lord's Prayer.
Mr Lloyd recited John McCrae's haunting 1915 poem In Flanders Field.
After the ceremony, the men received veteran's badges at the Ministry of Defence.
Dennis Goodwin, secretary of the World War One Veterans' Association, paid tribute to the veterans.
"These are very brave men, as witnessed by the fact that they made this journey to London today to stand in front of the country's, the Queen's monument to our glorious dead," he said.
"They are here to remember their survival and to pay homage to those who were less fortunate than they."
Mr Lloyd, who lost both his brothers between 1914 and 1918, said: "War is not a wonderful thing to be remembered, but those who died must never be forgotten."
Other guests at the Cenotaph service included Lord Kitchener, a great nephew of Kitchener, the head of the war ministry who rallied an army of a million men with his war-call "Britain needs you".
Germany declared war on France on 3 August, 1914, and Britain declared war on Germany on 4 August.
Some 900,000 soldiers from across the British empire died in action in the conflict, and more than two million were wounded.