The top secret germ warfare trials, which resulted in the deaths of thousands of animals for little scientific benefit, involved anthrax and the brucella bacteria.

The trials proceeded despite a full dress rehearsal in the United Kingdom throwing up serious problems.

In 1949, a Ministry of Defence team had identified the calm waters of the Caribbean, off the island of Antigua, as the ideal location to carry out field trials on the effects of exposure to the bacteria.

In order to keep the animals away from humans they were placed in containers on dinghies - and had either bombs containing germs dropped on them or were sprayed with the deadly bacteria.

Technical difficulties

But right from the start Operation Harness was beset by technical difficulties, coupled with incompetence.

The sheep and guinea pigs chosen for the experiments proved unsuitable and hundreds had to be shot or "discarded".

The Caribbean also turned out to be rougher than expected and the two converted tank landing vessels used for the operation proved unable to pick up the dinghies in open water.

Risk to locals

Instead, the tests were carried out just offshore from one of the islands in the area - despite the threat to dozens of local fishing boats working there.

On board the scientists' boats, the area set aside for the crews to change into their cumbersome protective clothing was said to be "so cramped as to be dangerous".

The official report of the operation admits that it was "uncommonly lucky" that only one member of the research team became infected by the germs being tested.

Catalogue of errors

The protective suits themselves were so heavy that the crews had to go through a lengthy acclimatisation process so they did not collapse of heat exhaustion.

Meanwhile the remote-controlled sampling equipment intended to test the bacteria emissions released into the air was affected by local radio signals and was apt to activate "spontaneously" at any time during the tests.

Simplicity the key

Finally the conditions at sea meant it was impossible to assess the levels of bacteria actually in the atmosphere - making the results of the tests meaningless.

The official report said: "Operation Harness has shown above all else that the keynote to success in field trials is simplicity. The technique was overcomplicated and impracticable."

Of the 600 sheep shipped from Texas for the trials 500 were shot after it became apparent they were unsuitable while the guinea pigs, sent over in batches of a 1,000, were simply described as "disastrous".

The animals often collapsed from the heat before they even had a chance of being infected by the germs.