Top secret War Office papers have revealed a strange and macabre weapons project tested by the Allies during World War II.
Lethal clouds of tiny poisoned darts were to be tipped with mustard gas to kill enemy troops without damaging nearby buildings or equipment.
The file has been released by the National Archives.
Test results were inconclusive and although the scientists remained enthusiastic, the project was shelved.
The concept was developed between 1941 and 1945 at the Porton Down research base in Wiltshire.
Research scientists thought clouds of poison darts, blasted from canisters high above the battlefield, could be even more lethal against enemy troop concentrations than high-explosive shells.
Mustard gas compounds in the needles would ensure anyone whose skin was broken would die a swift and horrible death, or at least have terrible injuries.
Assessing the effectiveness of the darts one report notes: "If penetrating into the flesh, will cause death if not plucked out within 30 seconds.
"If plucked out within this time, will cause disablement by collapse.
"Collapse occurs within one to five minutes, and death within 30 minutes."
A hand-written comment written next to this observed: "I doubt whether the darts can be plucked out. The paper tail would come off."
The scientists later pooled their knowledge with Canadian and American research teams.
In one experiment, the Canadians had dressed sheep and goats in two layers of battledress material and positioned them across a wide area, some in trenches, to be exposed to the killer darts.
Scientists predicted that symptoms displayed by the animals would be similar to those affecting humans.
"The pulse becomes very slow and the blood pressure falls. The subject collapses and lies on its side with twitching muscles.
"Where the dose is lethal, death occurs on 30 minutes, usually preceded by convulsions."
Despite some initial success, the project did not always run completely to plan.
When the scientists came to procure the needles needed for their experiments - it seems they caused not a little confusion.
An exchange of letters between Singer Sewing Machine Co. Ltd in Bristol and the Biology section at the experimental station in Porton Down illustrates how the need for secrecy stopped scientists explaining exactly what they needed the needles for.
One letter from Singer, dated December 24 1941, begins: "In reply to your letter of the 23rd instant, we are afraid we do not quite understand your requirements.
"From your remarks, it would seem that the needles are required for some other purpose, other than sewing machines."
Historians looking at the files today said they provided a "fantastic insight" into what the Allies were prepared to do to win the war.
Mark Dunton, a contemporary history specialist at the National Archives, said: "I have never heard of poisoned darts being used as a weapon of war in this way before.
"To our modern sensibilities it seems shocking and there's a real sense of viciousness about this weapon.
"But it shows the Allies were prepared to consider anything - no matter how gruesome - to secure a victory."
The file shows the darts were never used because they were a "highly uneconomical weapon" and only a small proportion of people would have been killed.