The Prince of Wales and his sons joined Canadian PM Justin Trudeau to pay tribute to those lost in the battle of Vimy Ridge a century ago.

Prince Charles, Prince William and Prince Harry were given a guided tour of the trenches in northern France, where Canadian troops, under British command, fought the German military.

Canada managed to capture the strategically-positioned ridge but around 3,600 of its soldiers were killed and more than 7,000 others injured.

The four-day battle was a decisive victory for the Allies and important in the development of Canada's national identity, as its troops attacked for the first time officially as the Canadian Corps.

The Queen was not present at the ceremony, but sent a message reminding that "it is our duty to remember and honour those who served so valiantly and who gave so much throughout the First World War".


Image: Canadian PM Justin Trudeau was met by Princes William and Harry

Prince Charles said victory at Vimy Ridge came "at an unbearably high cost", calling it the "single bloodiest day in Canadian military history", but reminding that it showed "Canada at its best".

The battle of Vimy Ridge began on 9 April 1917, and was part of a larger British-led offensive known as the Battle of Arras, in which around 159,000 Allied troops lost their life.

To mark the victory, all three royal men wore their military medals and also had the Canadian red poppy pinned to their lapels.

Image: British Royals with Canadian PM Trudeau and French President Hollande

In his speech, French President Francois Hollande made a veiled criticism of far-right presidential candidate Marine Le Pen who has been promoting an anti-immigrant, nationalist agenda.

"Those that fought at Vimy tell us that nationalism only leads to war and that fundamentalism only leads to destruction," he said.

While Canada's prime minister Justin Trudeau told the around 25,000 attending the ceremony that "the 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," he said.

"One hundred years later, we must say this, together. And we must believe it: Never again."