It was the summer of 1940, just weeks after a narrow escape by the British armies at Dunkirk, and the United Kingdom was braced for the onslaught of a threatened German invasion.

On the nation’s South Coast, one of many areas in danger of invasion from the sea, towns and villages were transformed by sandbags, barricades, and barbed wire into coastal redoubts where volunteers kept watch on the sea and the sky. The Battle of Britain was yet to reach its peak, but the drone of enemy planes could be heard flying overhead.

In the town of Highcliffe-on-Sea, the story goes, a secretive group of witches and spiritual seekers resolved to do what they could to defend their country. It’s said they arranged to meet in an ancient forest before midnight on August 1, 1940—the eve of Lammas Day, a harvest festival and one of the Greater Sabbats of the neopagan religion known as Wicca.

There, they are said to have staged a magical assault on the mind of Adolf Hitler in distant Berlin, by means of a ritual that became known by the mock military codename "Operation Cone of Power."

According to Gerald Gardner, the retired British civil servant who founded modern Wicca, the magical assault was based on secret knowledge passed down through generations of English witches. In his 1954 book Witchcraft Today, Gardner wrote that invasions had been turned back by magic twice before in English history—the first in 1588, when the Spanish Armada became discouraged after being scattered by storms, and then in 1805 when Napoleon called off his planned invasion of England.

An English folktale relates that the British admiral at the time of the Armada, Francis Drake, had joined a group of "sea witches" at a headland called Devil’s Point, near the naval port at Plymouth, to attack the approaching Spanish ships with a magical storm. It is said that on foggy days at Devil’s Point, the disembodied chants of Drake and the witches can still be heard. And in the early 19th century, Gardner wrote, another group of English witches cast spells to deter Napoleon.

Gardner claimed that similar rituals were used in 1940 against the Nazi leader by a secretive coven of witches who lived around Highcliffe: "Witches did cast spells, to stop Hitler landing after France fell," he wrote in Witchcraft Today. "They met, raised the great cone of power and directed the thought at Hitler's brain: 'You cannot cross the sea' ... just as their great-grandfathers had done to Boney and their remoter forefathers had done to the Spanish Armada …

"I am not saying that they stopped Hitler," Gardner added. "All I say is that I saw a very interesting ceremony performed with the intention of putting a certain idea into his mind … and though all the invasion barges were ready, the fact was that Hitler never even tried to come."

The British author and Wiccan Philip Heselton, who has researched Operation Cone of Power for Witchfather, his biography of Gardner, and several other books, thinks 17 people took part in the Lammas Eve ritual in 1940—including members of a local family said to be descended from witches.

They were joined by several Highcliffe residents, like Gardner, who had met through a local dramaturgical group called the Rosicrucian Crotona Fellowship, which had links to older esoteric groups such as the Co-Masons—a form of Freemasonry that admitted women—and the Hermetic Order of the Golden Dawn.

Heselton believes the group met in the New Forest, a few miles north of Highcliffe, near an ancient gallows-tree called the Naked Man, and made their way by foot to the site selected for the ritual, near a woodland called Ferny Knapp Inclosure.

In a forest clearing surrounded by pines, Heselton wrote in Witchfather, they marked out a witches' circle, the stage for their magical efforts. In place of a traditional bonfire—perhaps for fear of being spotted by enemy aircraft or local air defense wardens—a flashlight or shuttered lantern may have been placed to the east of the witches' circle, in the direction of Berlin, as a focus for their magical assaults. Naked, or "skyclad" as Wiccans say, they began to dance in a spiraling pattern around the circle, building up to the communal ecstatic state that they believed can control magical forces.

As they danced, their chants echoed the magical formula Gardner said had been used in the earlier ceremonies against the Armada and Napoleon, a psychological assault on the mind of Adolf Hitler that they hoped would weaken his resolve to invade England.

Historians have found no direct evidence beyond the writings of Gardner himself for the ritual, but the events he described have become important legends among modern Wiccans, says Professor Sabina Magliocco, an anthropologist and folklorist at California State University, Northridge and an initiated Gardnerian witch.

Magliocco says that frankly, she doesn’t know if the Cone of Power ritual really occurred. "As a folklorist, I'm interested in narratives because of what they tell us about people's values, and what they tell us about what people want to be true, even if the stories are not 100 percent true," she tells mental_floss.

Whether or not the ritual happened, Magliocco says, "it tells us something about what [those] witches wanted to be true … It’s about the power of witches to do something that is nearly impossible. It is also about the patriotism of these witches, and it also talks about the power of witchcraft to channel the energies of the earth, of nature, through their bodies, to create this Cone of Power."

Gardner wrote about Operation Cone of Power in two books about witchcraft in the 1950s. But questions about his version of events arose in the 1970s, when they were challenged by Amado Crowley, a writer who claimed to be the son and magical heir of the famous British occultist and writer Aleister Crowley.

Amado Crowley wrote that the ritual described by Gardner was a fiction based on a real wartime ritual carried out by his father, which he had witnessed as a boy. He claimed that this ritual, dubbed Operation Mistletoe, had taken place in the Ashdown Forest in Sussex in early 1941, with a detachment of Canadian soldiers dressed in wizardly robes and a dummy in Nazi uniform seated on a throne.

(In yet another version of Operation Mistletoe, related by author Richard Spence in his 2008 book Secret Agent 666: Aleister Crowley, British Intelligence and the Occult, the British authorities only wanted the superstitious Nazi leaders to learn that they were being attacked by British magic—but after the plan was dropped, Crowley went ahead on his own.)

Amado Crowley claimed that one result of his father’s magical attack was the bizarre episode in 1941 when the Nazi deputy leader Rudolph Hess made an unexpected solo flight across the North Sea in a Messerschmitt fighter plane, before bailing out by parachute over Scotland because he had lost his way and run out of fuel. Hess made his journey in the misguided belief that he could single-handedly convince the British to make peace with Germany, but he ended up in prison until he died in 1987.

Heselton and the British historian Ronald Hutton of Bristol University, who has written extensively on the history of the neopagan movement, are dismissive of Amado Crowley’s claims.

Hutton’s research, described in his history of modern witchcraft, The Triumph of the Moon, has found that the very detailed diaries Aleister Crowley wrote throughout his life make no mention at all of his supposed son and trainee magician, and no mention of any wartime activities or rituals (although Aleister wrote to Britain’s Naval Intelligence Division in 1939, two weeks after the German invasion of Poland, he was never offered a job).

In fact, there’s no evidence that the writer Amado Crowley had any genuine connection to Aleister Crowley at all.

"Amado Crowley's account of his previous life and his relations with [Aleister Crowley] is unproven in its entirety," Hutton tells mental_floss.

Hutton says it is not possible to know if Operation Cone of Power took place the way that Gardner described it. But he notes that Gardner’s account of Operation Cone of Power at least provided an opportunity to show Gardner’s patriotism when he was writing about the ritual in the 1950s—a time when neopagan witchcraft was routinely associated in the British media with stories of Satanism and ritual murder.

"If it didn't happen, then it was a wonderful way of trying to get people to regard Wiccans as being patriotic and fellow citizens, instead of being some kind of enemies of society," he says.

"Gerald [Gardner] produced the story of Operation Cone of Power after he'd coped with a great deal of barracking from the media about witches being inherently evil and perverted people. So this was one very good way of explaining that they weren't," Hutton says.

Heselton believes that Operation Cone of Power probably did take place as Gardner describes, because such magical ceremonies would have been an important expression of belief for the community of witches who have come to be known as the New Forest Coven.

"I think it's largely true. In fact, I turn the question on its head and reply that I think it extremely unlikely that something like this would not have happened," Heselton tells mental_floss.

Heselton points out that the group that Gardner was involved with, the so-called New Forest Coven of witches, were mostly too old to join the armed military or civil defense forces.

"But they were motivated by the times to take part in the defense of their country, however it could be achieved, so they used what skills they believed they had, which were magical ones," he says. "Operation Cone of Power was just the sort of thing they would have done."