Prince Charles and Nicolas Sarkozy lay wreaths in north-east France
Ceremonies have been held across the globe to mark the 90th anniversary of the end of World War I.
At a service in Verdun, north-east France, President Nicolas Sarkozy paid tribute to the millions who died during the four-year conflict.
French and German troops fought for eight months at Verdun in the longest battle of a war that reshaped Europe.
In the US, politicians took part in the annual Veterans Day ceremony at Arlington cemetery, near Washington.
Vice-President Dick Cheney and Defence Secretary Robert Gates were among those to participate in a wreath-laying ceremony at the national cemetery's Tomb of the Unknowns to honour those who have died in service to the US.
President George W Bush marked his final Veterans Day as commander-in-chief with a speech at a decommissioned aircraft carrier, the USS Intrepid, in New York.
He paid tribute to the armed forces and thanked veterans across the US for "standing up when your nation needed you the most".
President-elect Barack Obama, meanwhile, honoured fallen troops by laying a wreath at a memorial in Chicago's Soldier Field.
Earlier in London, three of the four surviving British World War I veterans attended a ceremony at the Cenotaph.
Henry Allingham, 112, Harry Patch, 110, and Bill Stone, 108, represented the Royal Air Force, Army and Royal Navy respectively.
At 1100 GMT, a two-minute silence was observed, marking the time - at the 11th hour of the 11th day of the 11th month - when the Armistice Treaty came into effect to end the war.
Earlier on Tuesday, President Sarkozy took part in an Armistice Day service in Verdun, and paid tribute to those who had died.
France will never forget the children who have fought for her
Mr Sarkozy, Prince Charles, Australia's Governor-General Quentin Bryce and Peter Mueller, president of the German Bundesrat, the upper house of parliament, laid wreaths in a field of 15,000 graves in front of the building.
A respectful silence was held and the bell tolled inside the ossuary, where Mr Sarkozy lit a memorial flame and a male choir sang the French national anthem.
Since the war, Verdun has become a symbol of Franco-German reconciliation.
But its hillside has come to symbolise World War I's awful savagery, says our correspondent. During the fighting, more than 60 million shells fell on the land, transforming it into a pitted piece of hell on earth.
As well as services across Europe, Iraq and Afghanistan, remembrance ceremonies have been held in Australia, which lost 60,000 men in the conflict.
Services were held across Australia to remember the dead
Australian Prime Minister Kevin Rudd used a speech at the Australian War Memorial in Canberra to issue a call for peace.
"We have all endured a most bloody century," he said.
"Let us resolve afresh at the dawn of this new century... that this might be a truly pacific peaceful century."
A lone bugler then played the Last Post, which is used to to commemorate the war dead in Commonwealth countries.
Meanwhile, German Chancellor Angela Merkel was in Warsaw to mark the anniversary of Poland's independence - which also came on 11 November 1918.
World War I was the world's first industrialised war.
It toppled four European empires, led to the creation of the Soviet Union and marked the end of Europe's long global hegemony.
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