November 8, 2018 12:00 PM EST

This Sunday — Nov. 11, 2018 — marks one hundred years since the signing of the armistice agreement that ended fighting in the First World War. World leaders will host events in Britain, France, Canada and beyond to commemorate the centennial and those that died in the war, holding parades, laying wreaths and keeping minutes of silence. But for many people, remembrance takes a more simple form: the poppy.

The story of how the poppy ended up on millions of lapels begins in the fields where the war was fought.

The conflict began in 1914 when a dispute between Serbia and Austria-Hungary pulled in their respective allies in Russia and Germany, collapsing the fragile peace between Europe’s great powers. As Britain and France got involved on Russia’s side, much of the fighting moved to the war’s western fronts in France and Belgium.

Vast swathes of once pristine countryside were trampled by soldiers and scorched by their weapons, leaving a muddy and seemingly barren mess. But poppies, which grow when their seeds are exposed to sunlight through disturbances to soil, managed to bloom.

In 1915, Lieutenant Alexis Helmer, a 22-year-old officer in the Canadian army, was killed in Belgium by an exploding shell. His friend Major John McCrae, a brigadier surgeon, was inspired by Helmer’s death to write the now famous poem In Flanders Fields, originally titled We Shall Not Sleep. Published in a London magazine in December of 1915, it proved extremely popular, with its three short stanzas glorifying the war dead, beginning with an invocation of the image of those flowers:

In Flanders fields the poppies blow

Between the crosses, row on row,

That mark our place; and in the sky

The larks, still bravely singing, fly

Scarce heard amid the guns below…

Three years later and two days before the armistice agreement was signed on Nov. 11, 1918, an American professor named Moina Michael came across the poem while volunteering at the New York headquarters of the Young Women’s Christian Association. She had the idea to wear a poppy as “an emblem of ‘keeping the faith with all who died,'” she recalled in her 1941 autobiography, The Miracle Flower. She went to Wanamaker’s department store and bought “two dozen small silk red four-petaled poppies,” which she gave to her coworkers before making more to sell.

It wasn’t until later that the poppies arrived in the U.K., the country most associated with their symbolism today.

In 1920, Anna Guérin, a member of the French branch of the YWCA, saw the poppies selling well at the American Legion convention in Cleveland. She realized that selling fabric poppies on a large scale was a practical way to fund charitable projects, particularly in Europe, where much of the population was still dealing with the economic and physical consequences of war.

Guérin traveled the world for her mission, persuading leaders in the U.S., Canada, New Zealand, Australia and Britain to adopt the flowers as a symbol of remembrance. They took off particularly well in Britain, where an initial order by the Royal British Legion of 9 million poppies rapidly sold out on Nov. 11, 1921. That first “poppy appeal” raised £106,000, the equivalent of roughly $6 million today.

Nov. 11 had already become a day of remembrance in the U.K. in 1919, with many Brits observing a minute’s silence at the exact moment the war had ended the year before: the eleventh minute of the eleventh hour of the eleventh month. Poppies were quickly incorporated into the celebration, which eventually became a day of remembrance for those who died in all of Britain’s wars. It is normally celebrated on the closest Sunday to Nov. 11 (the two coincide in 2018).

In 1922, Major George Howson founded the Disabled Society – soon renamed the Poppy Factory – to employ wounded and disabled veterans to make the poppies. Around 30 veterans are still employed in the factory in Richmond, southern England. The charity also supports ex-servicemen in their employment around the country.

In the U.K., the Royal British Legion distributes around 45 million poppies each year, with members of the public making donations in exchange for the flowers that can be pinned on clothes or on wreaths laid at the graves of the war dead. These days, poppies commemorate not only those who died in WWI, but also in WWII and later conflicts.

In the U.S., poppies are also worn for Memorial Day in May.

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