Greek Fire: The first chemical weapon?

By Kay Smith and Ruth R. Brown

We are in Bradford University, in the Archaeological Science Department. Dr Sonia O’Connor has switched on the X-ray machine, which is now humming away, and we are waiting with excitement to see what it reveals. It is focused on a small ceramic pot, the size and shape of a pomegranate. We are surrounded by the most modern analytical instruments used by world-leading archaeologists – cutting edge does not come into it. But let’s go back to the beginning. The object of our investigation is a long way in time and space from its origins, on the fringes of the Byzantine Empire, almost a millennium ago, at the time of the crusades.

Since ancient times, civilizations have feared fire, but of all the early attempts to use it as a controllable and effective weapon, none is as intriguing as the mysterious substance that today we call ‘Greek fire’. Despite the visions of terrifying and unimaginable destruction this conjures up, what we know is surprisingly insubstantial and inconclusive; the evidence is very difficult to interpret and Greek fire refuses to yield its secrets easily. The currently accepted account is that a Greek, Kallinikos of Heliopolis, invented, or possibly improved, a weapon that spouted fire and which, mounted on ships of the Byzantine fleet, defended Constantinople against Arab attacks in the 670s.

Depiction of the use of Greek fire, from the Madrid Skylitzes.

Frustratingly, after this there are few further references to Greek fire – which has led to the belief that it must have been a closely guarded state secret. Almost all the early references to Greek fire indicate that its main use was at sea, such as the occasion it was used to destroy an Arab fleet in AD 718. An account of this action, probably written later in the mid-eighth to the late ninth century, has perhaps the best description of Greek fire:

The front part of the ship had a bronze tube so arranged that the prepared fire could be projected forward to left or right and also made to fall from above. This tube was mounted on a false floor above the deck on which the specialist troops were accommodated and so raised above the attacking forces assembled in the prow. The fire was thrown either on the enemy’s ships or in the faces of the attacking troops.


And over two hundred years later, in AD 941, it was used to repel the attack on Constantinople by Igor the Russian. The great northern fleet was set upon by a much smaller flotilla from Byzantium:

…which threw liquid fire on all sides, from the prow, the stern and the sides, and the Russians, rather than burn, threw themselves into the sea; those weighed down by their armour were drowned, and those who were able to swim were burnt.

But with so little detailed or reliable evidence to go on, we may never know the secrets of Greek fire – what it was made from or how it worked is still hotly debated. We are fairly sure that originally Greek fire was a burning liquid, pumped out under pressure through the nozzle of some form of pump or siphon, which burned even on the surface of the sea, making a loud roaring noise and a lot of smoke. It was also apparently very effective. For sailors on wooden ships, fire was one of their greatest fears since they literally had nowhere to go – they could only burn to death or drown. Most importantly, it could prove decisive in battle.

Hand-siphon for Greek fire – Codex Vaticanus Graecus 1605

But what was it? This lack of documents has led to the belief that Greek fire must have been a closely guarded state secret. And this is strange since it does not disappear from written records completely until the later medieval period – surely the ‘secret’ would have leaked out? It has been the subject of a great deal of speculation, and stories about it and its terrifying effects have grown at the expense of real knowledge – as the secret was gradually forgotten, it passed into legend. For this very reason it has exerted a particular fascination on historians, researchers, and some military men who have dreamt of re-discovering its lost secrets.


Late nineteenth- and early twentieth-century historians speculated that it might be some sort of flammable liquid that had been mixed with saltpetre as an oxidising agent to provide oxygen for the burning process. More recently, J. R. Partington, in his work A History of Greek Fire and Gunpowder, suggested that it was made by distilling natural petroleum – a liquid similar to petrol (gasoline) without any added saltpetre – and pumping it out under pressure much like a modern-day flamethrower. However, today most researchers believe that at that period it was not possible to carry out the necessary distillation process, suggesting that instead it was made from natural undistilled petroleum.

Or the Pomegranate of Death?

But let’s move on again; much later, in the twelfth century, in the Middle East, the Crusaders met an unpleasant surprise. What they encountered was different – instead of a fiery liquid sprayed out of a pump, they were attacked by an incendiary material packed into bottles, or round glass or ceramic containers, thrown by hand or by trebuchet-like machines – like a modern-day hand grenade or a primitive mortar thrower. That it was being used very extensively in the Middle East is evident from a report in 1168 that 20,000 barrels of a flammable liquid, probably some form of petroleum, was used to burn down the city of Cairo. However, we still do not know what was inside the incendiaries – was it still Greek fire? And where does our little ceramic pot fit into this story?

This pottery fire bomb on display at the National Museum of Iran in Tehran. The device is dated 1200 – 1300 CE and said to have been loaded with ‘Greek fire’ and hurled at the enemy with a catapult. Photo by Hnapel / Wikimedia Commons

These small clay containers have been found all over the Near and Middle East, from Egypt, through Palestine and Syria, as far afield as Tashkent and Samarkand. They are quite small, fitting nicely into the hand, made of glass or ceramic, often shaped like a large pinecone or a pomegranate – which is where the name ‘grenade’ comes from. In the 1930s, archaeologists working in the citadel of the Syrian town of Hama made an intriguing discovery: a possible workshop for making clay grenades.


Even more excitingly, in one particular area were some much larger ceramic vessels, possibly used for distillation, in a room that appeared to have specialised ventilation – one wall had large circular openings just half a metre from the ground. Pieces of a burnt material were also found and identified as asphalt, a possible ingredient for an incendiary, together with resin or oil and lime. Perhaps this was where they made Greek fire to fill the small ceramic pots. The site dates to the first half of the thirteenth century, as it is known that Hama was largely destroyed by the Mongols in 1259.

Our clay pot is one of those found there. And now it is being x-rayed. Dr O’Connor switches off the machine and we crowd round the resultant images. Before the radiography, we did not know what to expect as to the construction of the small grenade. What they show first of all is that it was made in one piece – there is no evidence at all for any joins. The body is quite thick but appears to be much thicker in the bottom.

However, closer examination of the image indicates that this ‘thickening’ is actually something in the grenade itself – a residue, perhaps, or just hard packed sand, as that is what comes out in grains when it is turned upside down. What is clear, however, is that its contents were originally probably a liquid; the hole in the top is very small and it would be difficult to fill it with an incendiary mixture. The next step is to probe the inside and to investigate just what might be in this enigmatic object. Perhaps the clue to the secret of Greek fire lies closer to home than we expected!

Kay Smith and Ruth R. Brown are leading experts in medieval weaponry. Learn more about their work on or follow them on Twitter @LadySaltpetre and @Basiliscoe


See also: The Viking Axe

See also: The Lance

This article was originally published in Medieval Warfare magazine. Click here to buy that issue.