The nation fell silent on Armistice Day as the passing of the First World War generation was marked at a moving memorial service today.
The Queen, the Duke of Edinburgh, senior politicians and the heads of the armed forces gathered for the ceremony at Westminster Abbey, in central London.
Former and serving military personnel joined members of the public in standing for the traditional two-minute silence to remember the sacrifice of those who have died for their country.
Today's service at the Abbey was held following the deaths this year of the final three veterans of the war living in Britain.
William Stone died in January, aged 108, followed in July by Henry Allingham, 113, and Harry Patch, 111.
The Very Rev Dr John Hall, Dean of Westminster, opened the service by recalling the moment exactly 91 years ago when the guns fell silent in Europe.
He said in his bidding: "The Great War was over. Lives, friendships, families, societies, nations had been shattered. Everything had changed.
"On this day two years later and at this hour, an unknown warrior, chosen at random to represent all those of these islands who had fought and died, accorded the highest honour of a state funeral, was buried here.
"His grave was to become the focus of our national remembrance and to have international significance.
"Now that the last of his comrades in arms has gone to his eternal rest, we are here once more to remember.
"We remember, with grief, the gas and the mud, the barbed wire, the bombardment, the terror, the telegram; and, with gratitude, the courage and sacrifice.
"Never again, they said; the war to end all wars. With resolution we remember."
Prime Minister Gordon Brown and the Duchess of Gloucester, patron of the World War One Veterans Association, were among the British and foreign dignitaries at the service.
The head of the armed forces, Air Chief Marshal Sir Jock Stirrup, attended alongside the chiefs of staff of the Royal Navy, Admiral Sir Mark Stanhope, the Army, General Sir David Richards, and the Royal Air Force, Air Chief Marshal Sir Stephen Dalton.
Members of the public from across the UK with links to the conflict were also invited.
The beginning and end of the two-minute silence was marked by gunfire from the King's Troop Royal Horse Artillery, fired from Horse Guards Parade.
Defence Secretary Bob Ainsworth, who was among the congregation, paid tribute to those who fought in the First World War.
He said: "The war left an enduring impact on those who survived. They were determined that the sacrifices made by those who lost their lives would never be forgotten.
"Today we join together as a nation to honour that promise, and we will always do so".
Sir Jock added: "During the First World War the British military lost some two-thirds of a million dead - nearly 20,000 of those on just one day at the Battle of the Somme.
"These are numbers that are all but incomprehensible to us today. The total amounted to almost one in every 50 people in the land - hardly a community was untouched.
"Such sacrifice must never be forgotten, and today is an important part of that ongoing remembrance".
Also attending the service were former prime ministers Baroness Thatcher and Sir John Major. Tony Blair was unable to attend because he was visiting the Middle East in his role as Quartet envoy.
Others attending included TV presenter Michael Palin, journalist and broadcaster Ian Hislop, and Peter Owen, the nephew of First World War poet Wilfred Owen.
The Archbishop of Canterbury described the First World War as a "huge collective bereavement".
Dr Rowan Williams praised the achievement of the 1914/18 generation in repairing some of the "shattered idealism" that characterised the post-war period.
He said: "Some, at least, of those who tried to make sense of where God had been in all this realised that losing the safe, problem-solving God who protected nations and empires might itself be a gift, a moment of truth that brought the reality of God closer, recognised or not."
The Archbishop used his sermon to warn of the "readiness to forget the hard lessons learned by those who had been on the front line" that was prevalent in the 20th century.
He concluded: "The generation that has passed walked forward with vision and bravery, and held together the bonds of our society, our continent, our Commonwealth, through a terrible century.
"May we learn the lessons they learned, and God save us from learning them in the way they had to."
A Union Flag used to cover the bodies of the fallen during the First World War hung over the Grave of the Unknown Warrior in the Abbey during the service.
The "Padre's flag", as it is sometimes known, was flown daily on the Western Front and draped over makeshift altars at countless religious services, including before the Battle of the Somme, when the altar was a bucket turned on end in the corner of an old trench.
But it was also used by Army chaplain Reverend David Railton to cover hundreds of those killed in action before their burial in shallow graves.
Relatives of some of those who served in the First World War gave readings.
Anne Davidson, the daughter of Mr Stone, a former Royal Navy chief petty officer who fought in both World Wars, delivered a passage from the Bible.
Another reading came from 15-year-old Andrew Orr Ewing, whose family has a long tradition of serving the country in the Armed Forces.
His great-grandfather fought in the Battle of Jutland in 1916, aged just 16, his grandfather was also a Royal Navy officer, and his father, Lieutenant Colonel David Orr Ewing, is currently serving in Afghanistan with the Black Watch, 3rd Battalion Royal Regiment of Scotland.
Andrew, from Bridge of Earn, Perthshire, spoke of his pride in his family's military tradition.
He said: "The First World War should be remembered. It is quite an honour that I have been asked to do a reading when you think of how many people served."
Andrew is in the Combined Cadet Force at his school, Glenalmond College in Perthshire, although he currently has no plans to join the Armed Forces himself.
During the service the Queen placed a poppy wreath on the tomb of the Unknown Warrior.
The ring of scarlet flowers was carried through the Abbey by Victoria Cross holders Lance Corporal Johnson Beharry and Trooper Mark Donaldson escorted by Millie Scott, 17, from Stoke on Trent, and Victoria Newark, 15, from London.
Actor Jeremy Irons read Last Post by poet laureate Carol Ann Duffy, which was written to mark the deaths of the last surviving First World War veterans in the UK.
The choir sang Agnus Dei from Benjamin Britten's War Requiem, which uses the words from war poet Wilfred Owen's At a Calvary Near The Ancre.
Prayers were said for peace, for nations still suffering in war, for veterans, for innocent victims of conflict and for the Armed Forces.
A Royal Marines bugler sounded the Last Post followed by a Reveille, and the bells of the Abbey Church were rung half-muffled in honour of those who died after living through the war years.
Other events to mark Armistice Day were held around the country.
The Earl of Wessex led the congregation at a service of remembrance at the Armed Forces Memorial near Lichfield in Staffordshire.
Other guests included Defence Minister Quentin Davies and Major General Patrick Cordingley, who commanded the Desert Rats in the Gulf War.
The Royal British Legion also held two mass events, in London's Trafalgar Square and Swansea's Castle Square, so people could observe the two-minute silence with others.
The UK's involvement in the First World War lasted from August 4 1914 until November 11 1918.
More than 700,000 British servicemen were killed and some two million were wounded during the conflict.
Few families were untouched by the slaughter, as the long rows of names on war memorials up and down the country attest.
The sole British survivor of the First World War is now former seaman Claude Choules, who is aged 108 and lives in Perth, Australia.