Gruinard Island: Scotland’s 'Anthrax Island'

In 1942, the UK government sought to counter a potential Nazi-created biological bomb by developing germ weaponry of its own – and one focus of these experiments was the deadly anthrax bacterium.

However, the scientists knew how dangerous such experiments could be and they didn’t want to infect humans or livestock with this fatal disease.

That was why the uninhabited, tiny Gruinard Island seemed an ideal location to test the effects of an anthrax bomb. Located in the Scottish Highlands, the island was considered near enough to the mainland to allow easy travel there, but not near enough to spread infection.

Sheep were the living subjects of the anthrax experiments on Gruinard Island. The methodology was simple. A small detonation that released anthrax spores was set off near caged sheep. When the cloud of spores reached the sheep, the animals inhaled the spores and were infected. It took only a few days for the sheep to die, proving the method effective.

In fact, some farm animals on land nearby also died, although the true cause of their deaths was not revealed by the authorities.

Anthrax can infect humans and animals in several ways – by entering their bloodstream, by being eaten, or by being inhaled. The deadliest of these infection methods for humans is inhalation of spores, which results in death 95% of the time.

In nature, however, anthrax spores do not travel in large clouds floating through the air. Animals usually pick up anthrax infection through contact with anthrax spores in the soil or grass. That might be by eating the grass or breathing in air near the soil.

In turn, humans typically get anthrax through contact with infected animals or products of those animals, like wool.

The Gruinard Island experiments sought to see whether the lethal spores could be made into a bioweapon to infect large numbers of people or animals rapidly through an unnatural method of infection – blasts of spores on the wind.

In fact, the experiments on Gruinard Island were part of Operation Vegetarian – a broader investigation into germ warfare using anthrax.

Operation Vegetarian involved a plan to infect German cows with anthrax through a different method – consumption. Anthrax spores would be put into linseed cakes, which would then be dropped from the air into fields. Cows would eat the cakes and become infected. That would in turn infect and kill humans and dramatically harm Germany’s food supply.

While the infected linseed cakes were actually created, they were eventually destroyed without ever being used.

Once the experiments proved successful, the scientists burned or buried the infected animals to prevent them from spreading the infection.

But this did not remove the hardy anthrax spores from the island’s soil. Even burning Gruinard Island’s vegetation did not effectively clean up the spores, and nor did the passage of time.

The island was named a 'sacrifice zone' – as land that was permanently damaged. For decades, Gruinard Island was simply abandoned, and no-one was allowed to go there. Initially, the government did not even acknowledge that anthrax was present.

However, in the 1980s, Gruinard Island’s condition was brought into the public eye for the first time.

In 1981, a mysterious organisation calling itself the Dark Harvest Commandos began to write to newspapers and take action to draw attention to the contamination at Gruinard Island. They removed contaminated soil at the island and left it in meaningful places in England, such as at Porton Down, the birthplace of the experiments. Police were unable to find out the identity of the group members or how they had transported the soil so far from Gruinard Island.

Although the group concluded its protests on its own before any action was taken to clean up the island, its efforts were enough to prompt another clean-up.

This time, formaldehyde and water were sprayed over the island, and some of the soil was removed. The treatment was effective. For the first time since the 1940s, sheep were placed on the island – and they survived.

In 1990, the government announced that anthrax was gone from Gruinard Island. There was even a public ceremony in which a warning sign on the island was removed.

At last, the public got to see the details of the Gruinard Island experiments in 1997, when a film of the experiments was declassified.

Decades after Gruinard Island was set afire in the first clean-up process, it was on fire again.

In 2022, the island made headlines when a vast blaze covered it. Although the fire took place at a time of high risk for wildfires, the reason for the fire was never precisely determined.

Today, Gruinard Island still shows the effects of the 2022 wildfire. It has sheep, but no trees. Now, this small, unremarkable island shows few signs of its dramatic history.

To learn more about the non-biological weapons that were used in the war, take a look at our article on the deadliest weapons from World War Two. Or for more details about secretive endeavours, try our list of World War Two’s biggest deception campaigns.