Ancient Persians who gassed Romans were the first to use chemical weapons

Ancient Persians were the first to use chemical weapons when they gassed Roman soldiers with toxic fumes 2,000 years ago, researchers have discovered.

Archeologists have found the oldest evidence of chemical warfare yet after studying the bodies of 20 Roman soldiers' found underground in Syria 70 years ago.

Clues left at the scene revealed the Persians were lying in wait as the Romans dug a tunnel during a siege – then pumped in toxic gas – produced by sulphur crystals and bitumen – to kill all the Romans in minutes.