Ancient Chemical Warfare

Author: James, S., (2008), “Persian Chemical Warfare”, in Current World Archaeology 38, re-published in The Imperial Courier, Volume 5, Issue 2, THE RMRS, pp. 3-8.

Inter-war excavations found the remains of about 20 Roman soldiers in an ancient siege tunnel beneath the walls of the Syrian fortress city of Dura-Europos. No-one was sure how they had died.  Now archaeologist Simon James [1] has pieced together the forensic evidence for the world’s first poison-gas attack.  What follows is reproduced from the article that appeared in Current World Archaeology magazine (Issue 38).

Around the year AD 256, a ferocious siege took place on the Euphrates in eastern Syria.  In burning sun on battlements and siege-ramp, and in stifling tunnels dug beneath the defences, Roman and Persian battled for control of an ancient frontier-city.  Some of them appear to have suffered an especially gruesome end - in ways we tend to associate more with the trenches of the First World War than with the Classical world.

Europos, an old Macedonian-Greek military colony known to Syrians as Dura, ‘the stronghold’, had become the base for repeated Roman military invasions of the Parthian Empire.  Roman aggression - in quest of glory, booty, and territory - proved disastrous, precipitating the collapse of Parthia in the 220s AD and its replacement by the far more dangerous Sasanian Persian Empire, a new superpower spanning modern Iraq, Iran, and beyond.  Around AD 252, the Sasanians invaded Syria, one of Rome’s richest provinces, taking the capital, Antioch, before withdrawing from the region.  In response, the Romans massively strengthened the defences of Dura to block the Euphrates Road into the province.

Probably in AD 256, a Sasanian army attacked the city, intent on destroying this strategic obstacle to their further designs on Roman territory.  The dramatic story of the struggle for the city can be told in detail, but entirely from archaeological remains – there is no ancient written account of what happened.  Because the fallen city was abandoned and never reoccupied, the physical remains of the siegeworks, the weapons and equipment employed, and even the bodies of some of the combatants lay undisturbed until their rediscovery by archaeologists more than 1,600 years later.

The bodies in the mine  The grim details of the siege are still being investigated, not least through renewed excavations under Pierre Leriche and his colleagues in the current Franco-Syrian Mission to the site.  Such work builds on the publications and unpublished records of the earlier excavators, especially those left by Robert du Mesnil du Buisson, a French army officer and archaeologist who focused on digging the siegeworks during the major Yale-French Academy campaigns of 1928-1937.

Simon James’ long involvement with Dura began with the study of arms and armour from the excavations, of which du Mesnil recovered the lion’s share (James, 2004).  The harshest but also most fascinating of his discoveries came from a complex of mines excavated in 1932-1933 under Tower 19.  This lies north of the main city-gate, on the long wall that faced the principal Sasanian siege-camp across a flat plain, the only side of the city not protected by cliffs.  Here, du Mesnil seemed to have found the gruesome ‘holy grail’ of Roman military equipment studies: an entire squad of Roman soldiers who had simply fallen dead where they stood and remained undisturbed with all their equipment ever since.  The more James examined du Mesnil’s drawings and his description of the discovery (there are hardly any photos, and the bodies were neither studied nor kept), the more mysterious it all seemed.  Du Mesnil found about 20 bodies in the tunnel, in a tangle covering only a few square metres.  How did they come to lie here?  And how could so many men have met their deaths in such a small space?

Archaeology works in ways similar to crime-scene forensics.  Whether a “CSI” team confronted with the scene of a recent murder, or archaeologists dealing with an ancient site, investigators look for physical clues to try to work out the sequence of events leading up to the deposition of objects and human remains in their final resting-places.  Indeed, sometimes the two professions come together completely, when archaeologists help investigate modern murders and war-crime cases; recently they have been involved in excavations of mass graves of victims of Saddam in Iraq.  Understanding the mass fatality in the Tower 19 mine-complex at Dura requires just such a “CSI”-like approach, examining the positioning and interrelation of the bodies and associated evidence to help unravel how twenty Roman soldiers met their deaths there.

The siege of Dura-Europos  In AD 254-255, the Roman garrison made drastic preparation for a Sasanian assault. Dura’s relatively vulnerable western city-wall was massively strengthened against rams and undermining with a sloping mudbrick glacis outside and an earth rampart inside, entombing adjacent houses, temples, a synagogue, and a church.

Probably in the spring of AD 256, the Sasanians arrived.  Their assault was massive.  Along the western wall, three points of attack have been identified.  The great Palmyrene Gate saw ferocious fighting.  The Sasanians also began building a huge siege-ramp of earth and brick at the southern corner of the town, in parallel with mining operations designed to destroy an adjacent tower, from which men and catapults were raining projectiles onto the attackers.  It was successfully brought down - but the Romans had not been idle.  They had not only been raising their own walls and rampart to thwart the rising ramp, but they had also tunnelled into it.  As soon as it was ready to bear some massive tower machine, they fired their mine, collapsing the ramp.  Checkmate.

The third locus of attack lay north of the Palmyrene Gate.  At Tower 19, du Mesnil’s excavations showed that the Persians had tried another tactic.  They aimed to bring down a section of city wall, allowing a column of men to charge through the defences.  To effect this, they dug a mine under the tower and 11m of wall on its north side.  The logic is clear: towers were the main source of defensive fire, so the attackers aimed to destroy that closest to their unshielded right sides as they advanced across open ground towards the intended breach.  The spectacular remains left in the mines allow us to reconstruct in detail the struggle in the dark below Tower 19.

Probably starting in a chamber tomb in the necropolis outside the city, the Sasanians cut an approach tunnel through the soft gypsum, and then, once under the defences, dug upwards through the stratum of tough limestone surfacing the plain.  Once inside the body of the Roman rampart, they removed the lower courses of masonry from the wall, replacing them with timber props and combustibles.  However, the mining operations were impossible to conceal on the open plain.  The listening defenders located the tunnel and dug a countermine through their own earth rampart to meet it.  To thwart the intended attack, they needed to capture the Sasanian mine gallery.

But the defenders failed.  We know this because the countermine was found to contain about 20 skeletons, and, from the evidence of their arms and the coins found amongst the bones, we can identify them all as Romans.  The bodies were compressed into an area barely 2m by 3m.  Heavily burnt, they still gave off a ‘charnel reek’ when found.  The adjacent portion of their tunnel had been brought down by burning its pit-props.  Clearly, the Sasanians had defeated the Romans, inflicting many casualties, and then collapsed the Roman mine, preventing further interference with their own mining operation.

Eventually, the Sasanians fired their mine: the props burnt through, and the city’s defences crashed downwards.  The floors of Tower 19 collapsed, entombing a painted shield and horse armours.  But the wall did not topple outwards into the plain as intended.  It sank a metre vertically but stayed upright.  The defensive glacis and rampart had worked; no breach resulted.  Stalemate here, too.

A tangle of bodies  But how did so many dead Roman soldiers end up in such a tightly compressed tangle?  Du Mesnil thought that the Romans had been worsted in an underground fight for the mines, and, as they retreated, their officers outside the tunnel had panicked, and deliberately collapsed the countermine entrance to prevent the Sasanians entering the city.  The remaining trapped Romans stood at bay by the sealed entrance while the Sasanians fired the gallery, and then died on the spot from the effects of smoke and flame.  Simon James has never found this plausible.  Would the Romans really have just stood there while the Sasanians prepared to burn them alive?  Anyway, loss of the Roman mine did not directly imperil the city, so there was no need to collapse its entrance.  The gallery was only about 1.5m wide: the Sasanians could not have emerged more than one at a time, easy targets for the waiting Romans.

Careful re-examination of the surviving drawings of the tangle of Roman bodies shows this was not the result of a huddled group collapsing where they stood.  The bodies had been deliberately stacked.  Already dead - or at least incapacitated - they were piled up by the Sasanians.  First, some were placed slumped against the sides, their legs across the tunnel.  More were laid on top, across the gallery, then yet more piled on those, or laid against the Sasanian side of the growing heap, supplemented with Roman shields, to a height of a metre or more across the barely head-high tunnel.

Why would they do this?  Bodies are often used in war to provide ramparts, barriers, and cover.  Here, it seems, near the still-open entrance to the Roman gallery, the attackers used the bodies of the fallen defenders to make a wall, hindering any renewed Roman attack long enough for them to bring up bitumen, sulphur crystals, brushwood, and straw found at this spot by du Mesnil, and to start the conflagration which definitively collapsed the Roman mine.  Another solitary body that lay nearby is identifiable as a Sasanian.  Simon James guesses that he was the man who started the fire.  Perhaps lingering too long to ensure it was properly alight, he was himself overcome by the noxious fumes from the accelerants he used.

Gas attack  Such, then, was the gruesome fate of the Roman casualties; they lay not exactly where they had fallen, but where the Sasanians dumped them.  Yet this body stack prompts another question, one that implies a final horror.  How had the Sasanians managed to kill 20 Roman soldiers in a space just 10m long, narrow enough to touch both walls, and barely high enough to stand upright?  Perhaps it was terrible and sustained hand-to-hand grappling in the dark, where thrusts could not be easily dodged, and many fell quickly.  But could the Sasanians have poured men up into the gallery fast enough to inflict such a slaughter?  There is another, simpler explanation.  The Romans did not die in a fight at all.  On breaking into the Sasanian gallery, they were asphyxiated.

The Sasanians will have heard the Roman counter-miners.  They would have had time to prepare a deadly surprise.  As the Romans broke through, the Sasanians withdrew, dropping into their approach tunnel, where they had prepared closed braziers of hot charcoal and accumulated stocks of the sulphur and bitumen which they planned to use to burn the Roman mine.  All they had to do was to throw the combustibles onto the braziers.

The chimney effect between the lower approach mine and the higher Roman gallery, perhaps supplemented by the prevailing westerly wind blowing through the now connected tunnels, may have meant that they did not even need bellows.  The Roman tunnel would have filled with and heavy hydrocarbons, and deadly sulphur dioxide, which turns sulphurous acid when inhaled.

Roman soldiers at the back pressing forward will have prevented the escape of those nearest the fumes before they were overcome.  Those nearest the entrance will have realised the danger as dense clouds engulfed them in utter darkness, and tumbled choking back out of the mine, pursued by billowing smoke.  It is little wonder that the Romans hesitated to try to retake their mine, even when the Sasanians doused the smoke and started working feverishly to destroy the Roman tunnel.

The clues offered by the Tower 19 body-stack and the items found nearby appear to comprise the earliest archaeological evidence, albeit circumstantial, for chemical warfare; that is, for the deliberate use of chemical agents to incapacitate or kill enemy soldiers.  This is no idle fantasy.  We know from historical evidence that such methods were an established part of the repertoire of siege warfare techniques.  Livy records how the Greeks used braziers of burning feathers against the Romans in siege tunnels at Ambricia in 189 BC, and such use of smoke in mines was described in Roman military manuals of the following centuries.

High-tech war  The archaeology of the siege of Dura attests a highly dramatic incident, but it also has wider significance for our understanding of the ancient world.  While we know a great deal about the Roman military, by comparison we know astonishingly little, in archaeological or historical terms, about the armies of Rome’s eastern foes, the Parthians and Sasanians.

They were clearly powerful, especially in cavalry warfare on the dry steppe of Mesopotamia, where their horse-archers and armoured lancers long outmatched the legions.  Yet their ‘feudal’ armies are often thought to have been unable to match the engineering skills of the Romans, especially in siege warfare.  Dura gives the lie to this.  The Sasanian attackers knew and successfully employed a wide range of tested siege techniques, including a sophisticated siege ramp, various machines, mines - and, it would seem, gas/smoke generators.  Already in the 250s AD, the Sasanians possessed state-of-the-art siege capability, techniques pioneered by the Greeks and developed by the Romans.  The Dura evidence, then, gives us a vivid glimpse of the power and capability of the early Sasanian army; it also highlights a process of mutual influence and exchanges in military technology and techniques between the Greco-Roman and Iranian worlds.

During the siege, Romans and Sasanians used Greek tactics against each other.  The Roman garrison, recruited from Syrians, was in part equipped as Iranian-style horse-archers and armoured lancers, while the sole Sasanian soldier found in the Roman countermine wore iron mail copied from the Romans.  He also possessed an iron helmet of a design which was soon adopted and adapted by the Romans as their new standard helmet form.  Such archaeological details reveal just how intimately Roman and Sasanian soldiers were influencing, as well as fighting, each other across the Mesopotamian steppe.

We are not sure how the Sasanians broke into Dura, but eventually the city fell, to be sacked, depopulated, and permanently abandoned.  Soon after, in AD 259-260, a far greater disaster befell Rome in Syria.  At Edessa, the Sasanian ruler, Shapur the Great captured the Roman emperor Valerian in battle.  It was the nadir of Roman fortunes.  Rome eventually recovered prestige and power in the East, and for the next 400 years the two empires sometimes fought, sometimes coexisted, sometimes collaborated against common enemies - before Islam shattered the power of both and remade the Middle East on a new template.  Dura was forgotten - until archaeologists began to piece together its story.  The current Franco-Syrian Mission continues to unlock yet more secrets of this remarkable site, not least among them the remains of the final, fatal siege and sack of the city.  The tale of the battle for Dura remains unfinished, with many surprises still in store.

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References:

1.  James, S., (2004), “The Excavations at Dura-Europos 1928 to 1937 Final Report VII: The Arms and Armour and other Military Equipment”, London: British Museum Press.

2.  On ancient chemical and biological warfare, see Mayor, A. (2003), “Greek Fire, Poison Arrows, and Scorpion bombs: Biological and Chemical Warfare in the Ancient World”, London: Duckworth.

Endnotes:

1.  Simon James is Reader in Archaeology at the University of Leicester (stj3@leicester.ac.uk).

2.  Further information about Dura-Europos is available at www.le.ac.uk/ar/stj/dura.htm.