In summer and autumn of 1917, teenage Elsie Wright and her adolescent cousin, Frances Griffiths, borrowed a glass-plate camera from Wright’s father and tromped to Cottingley Beck, in West Yorkshire. They photographed each other on the bank of the stream and in the grass of a sun-dappled glen—and also captured some special guests.

One image shows Griffiths, looking wistful, chin in hand, with a cavorting troupe of fairies. In another, a smiling Wright greets a gnome high-stepping through the grass.

For those inclined to believe in the existence of small, magical forest creatures, the photos felt like ironclad proof—the ultimate rebuke to the skeptics, clear as day. Some of the most ardent support for the veracity of the images, known as the “Cottingley Fairies,” came from Arthur Conan Doyle. Years after he had dreamed up Sherlock Holmes, the author campaigned for belief in Spiritualism, which boomed during and after World War I. Conan Doyle, who had lost his son Kingsley in the war, seized on the girls’ photographs as evidence of the mystical world. He compiled his arguments into a volume called The Coming of the Fairies. The pictures, he wrote, “represent either the most elaborate and ingenious hoax ever played upon the public, or else they constitute an event in human history which may in the future appear to have been epoch-making in its character.”

Read More For Sale: Legendary Photographic ‘Proof’ of Fairies and Gnomes – Atlas Obscura