Heroes of the liberation of Europe were joined by world leaders as tens of thousands of people remembered the courage and sacrifices of servicemen on the 70th anniversary of D-Day.
British veterans, most making their final pilgrimage to Normandy to revisit the scene of their momentous invasion, took part in events to honour those who fell in the pursuit of freedom.
This week troops, now in their late 80s and 90s, returned to the beaches, cemeteries and villages of northern France through which they helped defeat Nazi tyranny.
Some 156,000 Allied troops landed on the five invasion beaches on June 6, 1944, in an operation which wartime prime minister Winston Churchill described as: ''Undoubtedly the most complicated and difficult that has ever taken place.''
It marked the beginning of an 80-day campaign to liberate Normandy which involved three million troops and cost the lives of 250,000 people.
To mark the 70th anniversary, the Queen issued a message to veterans, saying their "brave actions and dogged determination" established a vital foothold in occupied Europe.
In Arromanches, the Duke of Cambridge, said: "It is vital that the sacrifice - and the reasons for that sacrifice - are never forgotten by our generation and generations to come."
Prime Minister David Cameron, who was in Normandy along with Nick Clegg, Ed Miliband and Scotland's First Minister Alex Salmond, said he felt a mixture of "awe and gratitude" after meeting veterans.
He said: "I think the clear evidence of what happened in 1944 and 1945 is the importance of standing up together for freedom and security."
Today the commemorations were brought to a climax with an international ceremony attended by a host of world leaders at Sword Beach.
French president Francois Hollande issued a rallying cry to the world, calling on nations to fight against threats to peace just as the D-Day troops did 70 years ago.
In a moving address, Mr Hollande said people needed the same courage as the Allied forces who fought and died to end Nazi tyranny.
To loud applause from veterans and heads of state - including the Queen - Mr Hollande also said he wanted to see the beaches of Normandy become a Unesco World Heritage site.
Mr Hollande said it was the world's duty to fight extremism and fundamentalism adding: "It's up to us to have the same vision, the same courage, to be just as bright and have the same determination as those who came to these beaches 70 years ago."
He said the threats to cohesion today ranged from terrorism to global warming and mass unemployment and that they could cause conflict.
Archive black and white movie footage and performers were used to tell the story of the atrocities of the Nazi regime and the exploits of the Allied troops whose invasion of mainland Europe would eventually lead to the downfall of Hitler's regime.
Among the heads of state who attended were US president Barack Obama, Russia's president Vladimir Putin, King Harald V of Norway and President Milos Zeman of the Czech Republic.
There had been speculation that a potentially awkward encounter might occur between Charles and Mr Putin, following the prince's recent remarks about the Russian president.
He reportedly criticised Mr Putin to a woman during a tour last month to Canada, comparing him with Adolf Hitler after she told him how she fled Nazi persecution.
But the two men did not meet in the large VIP stand as the heir to the throne arrived after the Russian leader.
And, in what might be seen as a conciliatory move, Mr Putin lightly applauded as the Prince walked up to meet Mr Hollande.
In Arromanches, the Duke and Duchess of Cambridge applauded as veterans paraded in front of them yards from Gold Beach in a Normandy Veterans' Association service.
He said: "It is, of course, correct and fitting that we honour today the veterans of all nations who took part in Operation Overlord.
"It is essential, too, that we never forget the friends and companions of those veterans who gave everything for our freedom on the sixth of June, and during the days and months that followed."
Earlier the Queen paid her own tribute to those who made the ultimate sacrifice for "freedom in Europe'' laying a wreath in a military grave - the last resting place of many British D-Day troops.
She left her floral tribute during a solemn open air ceremony at the Commonwealth War Graves Commission cemetery in Bayeux, the first town to be liberated following the Normandy landings.
Charles also laid a wreath as did Prime Minister David Cameron and other world leaders.
The US president marked the contribution of his nation's forces to D-Day when he paid tribute to their sacrifices at the Normandy American Cemetery and Memorial, where nearly 10,000 servicemen are buried.
Mr Obama said the American commitment to liberty, which is ''written in blood'' on the beaches of Normandy, endures with a new generation.
And he told D-Day veterans gathered above Omaha beach that their legacy was in good hands.