Centenary commemorations for Canadians who gave lives for peace in Europe
The sacrifice of First World War Canadian soldiers who helped forge peace in Europe and a national identity for their country has been praised by world leaders at a ceremony.
The Prince of Wales described the efforts of Canadian troops who fought at the Battle of Vimy Ridge, launched 100 years ago to the day, as setting "an extraordinary example of selflessness for our future generations".
While Canada's prime minister Justin Trudeau said: "The burden, they bore. And, the country they made.
"Because this, too, is why we're here. Why we remember."
Charles told thousands of Canadians gathered along with France's president Francois Hollande and other dignitaries that: "The long shadows of the thousands who fell here still touch us today."
The battle is fundamental in the history of Canada as on a snow-swept French hillside four military divisions from the nation attacked together for the first time as the Canadian Corps, and their bravery in breaking German defences earned them the respect of the world.
The battle, begun on April 9 1917, was part of a larger British-led offensive, featuring Australian troops and Scottish regiments, known as the Battle of Arras, which was a diversionary move to help a major French attack further south.
Delivering part of his address in French Charles added: "We honour those who served so gallantly, and who gave so much.
"Their loss inspires us to do all in our power to prevent such senseless loss from ever happening again."
The event was staged in the shadow of the towering Canadian National Vimy Memorial built on Hill 145, the highest point of Vimy Ridge captured by Canadian and British troops after four days of fighting.
Among the guests was the Duke of Cambridge and Prince Harry who laid the final pair of thousands of boots left at the monument to symbolise the 3,598 Canadians killed in the major operation.
In his tribute to his countrymen who fought and died on Vimy Ridge Mr Trudeau told the thousands attending the ceremony in blazing spring sunshine: "But this monument is also symbolic of Canada's birth and our enduring commitment to peace.
"As I see the faces gathered here, veterans, soldiers, caregivers, so many young people, I can't help but feel a torch is being passed.
"One hundred years later, we must say this, together. And we must believe it: Never again."
In his speech Mr Hollande made a veiled criticism of far-right French presidential candidate Marine Le Pen who has been promoting an anti-immigrant, nationalist agenda.
France votes in the first round of the presidential election in two weeks time with the controversial politician expected to reach the run-off.
The president said: "Those that fought at Vimy tell us that nationalism only leads to war and that fundamentalism only leads to destruction."
And speaking about French-Canadian co-operation on the world stage he appeared to attack the recent chemical attack on Syrian civilians that has been widely attributed to the Assad regime.
He said: "It's what we do when we condemn chemical massacres committed by a criminal regime."
The Canadian-led victory at Vimy Ridge was not only due to the bravery of the men, with four Victoria Crosses being awarded, but detailed infantry training.
The troops practised in dummy Germany trenches and a pinpoint British artillery bombardment allowed the men to advance behind the raining shells giving them the upper hand over the pinned-down enemy.
On a stage at the memorial the human side of the conflict was brought to life with actors playing the part of soldiers and music and dance adding an artistic dimension to the tributes.
The Last Post was played by a bugler using an instrument that had been sounded in the very area, as it had belonged to George William Shaw, a member of the Canadian Armed Forces who served at Vimy Ridge, and was loaned by his grandson.
Earlier the Queen had sent a message to the people of Canada telling them it was everyone's duty to remember the sacrifices of their countrymen who served in the 1917 battle.
When they left the ceremony with Mr Trudeau and the French president, William and Harry were mobbed by Canadians, youth groups, military veterans and relatives of Vimy Ridge troops.
There were dozens of shouts of "thanks so much" and "thanks from Canada" as they moved towards their official cars.
William was asked to pose for a selfie with one woman who had flown from Alberta and he quipped: "You had better be quick."
And he told another visitor pointing to his face "you've been in the sun a long time".