This would make for a particularly vile alternative history.
The truth was that Gruinard Island had been the site of a clandestine attempt by the UK during World War Two to weaponise anthrax, a deadly bacterial infection. The exact details of what had happened there would only come to light when in 1997 the government declassified a film that the military had shot at the time, which detailed the experiments.
The plan was to infect linseed cakes with Anthrax spores and drop them by plane into cattle pastures around Germany. The cows would eat the cakes and contract anthrax, as would those who ate the infected meat. Anthrax is a naturally occurring but deadly organism. Symptoms of infection can take time to fully appear but when they do they are horrific and can become lethal very quickly. The proposed plan would have decimated Germany's meat supply, and triggered a nationwide anthrax contamination, resulting in an enormous death toll.
A military team, under the supervision of scientists, then began to conduct chilling experiments. Using livestock brought over to the island to serve as test subjects, they started a series of trials releasing anthrax spores across the island's terrain. The results were devastating: within days of exposure the sheep started showing symptoms and rapidly began to die. Their infected bodies were autopsied and then incinerated or buried under tonnes of rubble.
In the decades that followed the end of World War Two, attempts were made to decontaminate the site using chemical treatments and controlled burning, but they proved largely ineffective. A series of tests in 1971 showed that while there were no longer anthrax spores on the surface, they still lingered on in the soil underneath, posing a grave risk to anyone setting foot on the island. Years later, scientists returned to try decontamination efforts again, soaking the island in a mixture of seawater and formaldehyde, as well as removing and incinerating contaminated topsoil. This time they were more successful and finally, on 24 April 1990, after 48 years of quarantine, the UK Government declared Gruinard Island anthrax-free.
https://www.bbc.com/culture/article/20240419-britains-mysterious-ww2-island-of-death
