Ancient Persians were the first to use chemical warfare against their enemies, a study has suggested.
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A UK researcher said he found evidence that the Persian Empire used poisonous gases on the Roman city of Dura, Eastern Syria, in the 3rd Century AD.
The theory is based on the discovery of remains of about 20 Roman soldiers found at the base of the city wall.
The study shows that the Persians dug a mine underneath the wall in order to enter the city.
They also ignited bitumen and sulphur crystals to produce dense poisonous gases, suggested Simon James, an archaeologist at the University of Leicester.
The Roman assault party was unconscious in seconds, dead in minutes
Dr Simon James,
University of LeicesterHe added that underground bellows or chimneys probably helped generate and distribute the deadly fumes.
The Romans apparently responded with counter-mines in an effort to thwart the siege.
