More than 1 million people were killed, wounded or went missing in the Battle of the Somme in northern France, pitting English, Irish, Scottish, Welsh, and French troops against German ones from July 1 to November 18, 1916.
Britain once again held a moment of silence to mark 100 years since the bloodiest day of British military history.
But the main focus for the international commemoration was in northern France. The main ceremony started with the sound of cannon shots shortly after noon at the monumental Memorial of Thiepvalwith the participation of 600 British and French children. Each of them laid a flower crown on the 600 British and French graves of the cemetery.
Many descendants of soldiers, often wearing poppy and cornflower pins — the British and French symbols to remember those who died — attended the event.
Guests and dignitaries, including French President Francois Hollande, Cameron and Britain’s Prince Charles read texts describing the horrific scenes and the devastated landscapes of the front line in 1916, and French, British and Irish songs inspired by the war were sung.
The Memorial of Thiepval, built in 1932 by the British government, is dedicated to the 73,367 British and South African soldiers missing in the Somme area during World War I.
Thousands of petals of poppies and cornflowers were released from the top of the monument in complete silence.
Despite the British vote to leave the EU and their opposite political views, the socialist Hollande and the conservative Cameron seized the occasion to stress their World War I alliance and show their attachment to the ideas underpinning European unity.
“In many ways, there is a link between the current events we’re discussing and what happened 100 years ago. It’s the importance of keeping peace and security and stability on our continent,” Cameron told members of parliament on Wednesday.
“We’re going to be standing together and remembering the sacrifices all those years ago.”
Others at Friday’s event included Prince Charles’ wife Camilla, his sons Prince William and Prince Harry and William’s wife Kate, President Michael D Higgins and former German President Horst Koehler.
“History connects us,” Hollande said Wednesday at a tense EU summit focused on how to cope with Britain’s departure.
“France and the United Kingdom are very close, connected by a tunnel, with a very significant presence of French people in the United Kingdom and of British people in France.”
In cities around Britain, commuters and shoppers were met by the eerie sight of WWI soldiers in uniforms.
Young men in vintage uniforms mingled silently on high streets, in cafes, and in railway stations across the country during the morning rush hour.
Some sang wartime songs, others handed out simple cards, each bearing the name of a soldier killed on the first day of the battle, and the social media hashtag #wearehere.
Later, Charles and Camilla paid tribute to Northern Irish and Canadian soldiers in in Thiepval and in the village of Beaumont-Hamel.
Last month, Hollande and German chancellor Angela Merkel commemorated the centenary of the Battle of Verdun, the longest battle of World War I.
The leaders praised their countries’ friendship, risen from the ashes of two world wars and strengthened through EU cooperation.