The Roman Fort at Dura, SyriaFrom Live Science:
A fierce battle between Roman defenders and invading Persians took place at Dura, a garrison city on the Euphrates River in what is now Syria. That was around a.d. 256, nearly seventeen centuries before the 1925 Geneva Protocol outlawed the use of poison or asphyxiating gas in warfare. The ban might have altered the outcome at Dura had it been in force at the time.
Twenty Roman soldiers died quickly in a tunnel when the Persians forced in hot, sulfurous gas, says archaeologist Simon T. James of the University of Leicester in England. The Roman tunnel was intended to head off one that the Persians were digging to undermine a city wall. James points to sulfur crystals and pitch found in the Roman tunnel near its interception of the Persian one. When ignited, the substances produce an asphyxiating gas.
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