Around AD 256: 19 Romans Died Underground — Persia May Have Used Toxic Smoke

At least nineteen Roman soldiers died in tunnels beneath Dura-Europos.
A Sasanian soldier died there too. Their final moments remain unknown.
Did the Persians use toxic smoke—or did combat and fire kill them?
Follow the excavation records and competing archaeological explanations.
An evidence-led mystery from the siege of Dura around AD 256.