It was the last sky at least half a million soldiers – British, French, Belgian and German – would see.
The land has healed now but the scars have not, and as the Royal British Legion launched its annual poppy appeal, a century on from the armistice, the mud became their memorial.
A vast artwork, hewn from the land and infused with poppy seeds, has been installed in time for the Remembrance service, at Ripon Cathedral.
Dan Metcalfe created it from wet soil taken from fields on the outskirts of the city which had once housed one of Britain’s largest military camps, and from battlefield mud collected from Flanders.
He had been moved to design it after hearing stories of Hospital Wood Field on what had become his father’s farm.
“Ploughing the field as a child, objects would come to the surface that just gave a hint of what had gone on there,” he said.
“They say a million men came through there during the four years and it was 30,000-strong. That’s more than double the population of Ripon now.”
Among them was the poet Wilfred Owen, who went there to recuperate from shell shock, before going back to the front to die. The camp, he said, was “awful”.
Mr Metcalfe’s work, created with the illustrator Jeanne Mundy and recalling the style of the 1917 picture by the war photographer Ernest Brooks, depicts five battle weary silhouettes returning from the front, their backs to the past and facing the future.
“The silhouettes are no longer at war, but neither are they yet fully at peace,” Mr Metcalfe said.
Deep within the mud are millions of ungerminated poppy seeds. When the work, which has taken four years to realise and is known as Seeds of Hope, is decommissioned from the Cathedral next month, pieces will be offered to the public to create their own memorial gardens.
“The subject of hope is not immediately obvious when looking at the Great War. You do have to search for it and work at it, but it is there,” said Mr Metcalfe, whose background is in agriculture and landscaping, as well as art.
“Rather like the tenacious poppy seeds, legacy and hope are buried deep and can sit dormant and unseen ready to germinate and flourish from the mire given the correct circumstances.
“The seeds will allow the work to continue indefinitely in another form.”
The launch of the appeal yesterday saw another artwork, a six-metre-high poppy installation, unveiled at the National Maritime Museum in Greenwich.
Barbara Weatherill, a 93-year-old veteran of the Second World War, went to see it before meeting the Prime Minister at Downing Street, to declare the fund officially open.
Ms Weatherill, who is from Selby and was a driver-mechanic with the Royal Artillery, said: “It means a very great deal because it is a continuation of the good work of remembrance.
“I think when the poppies first appeared in Flanders, nobody had any idea of the impact it would have 100 years later.”
She added: “It means a lot to me, it always has done, because my parents served in the First World War, both my mother and father.”
Mrs May said she was proud to be a part of the appeal. “I hope the country will join me in wearing a poppy and giving thanks to the whole armed forces community for their dedication, sacrifice and bravery,” she said.
Founded in 1921, the Poppy Appeal raises funds for servicemen and women and their families. In 2015, more than 11 million poppies were made.
In addition to the Greenwich installation, smaller artworks were unveiled yesterday at Brighton Pavilion, the Library of Birmingham, and Ballyclare Football Club in Co Antrim.