The Somme Offensive, waged in 1916, was intended to hasten a victory for the allies against the German empire, but after four months of trench warfare, more than a million men were dead or wounded and the Great War would go on to last another two years.

In a solemn ceremony at the Thiepval memorial in northern France, Macron and May honored allied soldiers who died at the Somme. The wreath they put down combined the poppy and le bleuet flowers, national emblems of remembrance in Britain and France.

Thiepval’s memorial stands on high ground overlooking the Somme river and commemorates more than 72,000 British and South African soldiers who died and have no known grave. May said the day’s ceremonies were a time to “reflect on our shared history, but also look ahead to our shared future”.

“We remember the heroes who lost their lives in the horror of the trenches. As the sun sets on 100 years of remembrance, we will never forget their sacrifice,” she said.

The two leaders had first held a working lunch in the town of Albert, in the heart of the Somme region, at a time May is intensifying efforts to secure European support for a Brexit deal. A Macron aide declined to comment on the nature of the discussions.

To commemorate the 100th anniversary of the end of the war this weekend, Macron will welcome world leaders including U.S. President Donald Trump, German Chancellor Angela Merkel and Russia’s Vladimir Putin. Macron then hosts an inaugural Paris Peace Forum, which Trump will not attend.

Earlier on Friday, May laid wreaths at the graves of the first and last British soldiers killed in the war at the St Symphorien cemetery near Mons in Belgium, accompanied by Belgian Prime Minister Charles Michel. More than 500 German and British Commonwealth soldiers are buried at the war cemetery.

Among them is Private John Parr, a reconnaissance soldier who was killed on Aug. 21, 1914, when his commanding officer sent him into enemy territory on his bicycle to gather intelligence on German military moves. He was 17 years old.

Parr’s headstone stands opposite that of George Ellison, who died 90 minutes before the Armistice came into effect on Nov 11, 1918.

At Parr’s grave, May left a note: “In that rich earth a richer dust concealed”, words taken from a sonnet written by Rupert Brooke at the start of World War One.