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The Medieval World's Most Terrifying Weapon Is Still A Mystery Today

"Greek fire" was the real-life version of Game of Thrones's wildfire. Nobody knows how it was made.


Dr. Katie Spalding

Katie has a PhD in maths, specializing in the intersection of dynamical systems and number theory.

Freelance Writer

Image from an illuminated manuscript, the Madrid Skylitzes, showing Greek fire in use against the fleet of Thomas the Slav

Image from an illuminated manuscript, the Madrid Skylitzes, showing Greek fire in use against the fleet of Thomas the Slav

Image credit: Public Domain

In the Ancient Greek world, there were four elements: Earth, Air, Fire, and Water. Not only did the model have the benefit of describing everything in the known universe, but it was also beautifully symmetrical: Air, being hot and wet, was the opposite of cold dry Earth, while Water, with its cold, wet properties, perfectly canceled out the hot, dry element of Fire.

It may seem strange, therefore, that it was also the Greeks who gave the world the perfect counterexample to this four-elemental balance. “Greek fire,” as it was known to the medieval world, was a deadly and terrifying weapon that baffled those it was wielded against – not least because, in being impervious to water, it appeared to defy the laws of physics.


But what was it? Where did it come from? And even more mysteriously – where did it go?

Greek fire wasn’t Greek

Perhaps the first thing you have to know about Greek fire is that it wasn’t, in fact, Greek. 

“The Arabs, Bulgars, Russians, and others who were reported to have experienced the real Greek fire would never have called it that,” points out Alex Roland, now Professor Emeritus of History at Duke University and an expert in world military history, in a 1992 paper on the weapon.

There’s a very good reason for that: the substance – or substances, we should really say – we now know as “Greek fire” was actually used in the Byzantine Empire, starting in the seventh century CE.


And to the medieval world, the Byzantines were not Greeks – they were Romans. “‘Roman fire’ is in fact one of the original names of the weapon,” Roland explains.

So, in that case, where did the technology’s Hellenistic moniker come from? “The name of the substance is confused and confusing,” admits Roland. In fact, it wasn’t until many centuries later that we see the term “Greek fire” being used – and it didn’t even refer to the original concoction in any case, he explains: “The term ‘Greek fire’ was applied to the weapon by Crusaders from the West, but by then the original […] had long since disappeared.”

Greek fire may have changed world history

The second thing you should know about Greek fire is that it was likely invented as revenge.

While we really don’t have very much actual evidence about the technology, the generally accepted origin story of Greek fire places its invention at the hands of Kallinikos of Heliopolis. A Greek-speaking Jewish refugee, Kallinikos had escaped from Byzantine Syria when it was invaded by the Muslim Rashidun Caliphate. He arrived in Byzantium – the capital city of the Empire, which would later be renamed first Constantinople and then Istanbul – and immediately set about creating a weapon able to fend off his new home from the same armies that had forced him to flee Heliopolis.


He didn’t have to wait long. According to contemporary Arabic sources, the first use of Greek fire against them occurred during the 674-80 CE “war of seven years.” And it was incredibly successful: “Relying on [the] weapon, the Byzantines succeeded in driving off the Arab fleet and lifting the siege of Constantinople,” writes Roland.

It was a victory that some modern scholars place as one of the most critical in history. To British scholar and archaeologist Romilly Jenkins, it marked no less than “a turning point in the history of mankind”; meanwhile the Russian historian George Ostrogorsky posited in 1969 that “the Byzantine capital was the last dam left to withstand the rising Muslim tide […] that it held saved not only the Byzantine Empire, but the whole of European civilization.”

Greek fire was terrifying

There’s no question that, to the enemies who faced it, Greek fire must have been terrifying. Arriving with noise and smoke, blasting green flames across the water to their ships, and seemingly impossible to extinguish without the right mix of urine, sand, and vinegar, prospective invaders were said to “rather than burn, threw themselves into the sea.”

“[The ships] threw liquid fire on all sides, from the prow, the stern and the sides,” reads a mid-eighth to ninth-century account of the weapon’s use against an attacking Russian force. “Those weighed down by their armor were drowned, and those who were able to swim were burnt.”


Three centuries later – and now in the hands of the Muslim Saracen army – the weapon was still scaring the bejeezus out of invaders. “[A] tail of fire that […] was as big as a great spear,” recorded Jean de Joinville in his memoir of the Seventh Crusade, “and it made such a noise as it came, that it sounded like the thunder of heaven.” 

“It looked like a dragon flying through the air. Such a bright light did it cast, that one could see all over the camp as though it were day, by reason of the great mass of fire, and the brilliance of the light that it shed.”

But what actually was Greek fire?

Clearly, then, Greek fire was something important. Revered by the Byzantines who held it, and obsessed over by those enemies of the Empire who had felt its effects first-hand, there are accounts of the weapon’s effects from observers hailing from Sweden to Pisa to Iraq.

All this might make it surprising that, to this day, we don’t really know what it actually was.


Contemporary sources are fairly clear on descriptions of the weapon: “The characteristics of Greek fire, as it is represented in the literature in the period from 678 to 1204, may be reduced to four,” Roland notes. “First, it burned in water; some even reported that it was ignited by water, but this is not generally accepted.” 

“Second, Greek fire was always portrayed as a liquid,” he continues. “Third, at least when used at sea” – which, he clarifies, was virtually always – “it was always shot from tubes or siphons located in the bows of specially designed fire ships.”

“Finally, many firsthand accounts of its use report the appearance of smoke and a loud discharge or booming noise when the flaming liquid left the tube or siphon,” he writes. “This characteristic was to become especially important in the historical controversy over the composition of Greek fire.”

But beyond these descriptions of how the fire behaved, and how it was wielded, Roland writes, “there is no undisputed primary evidence to help pin down just what Greek fire was.”


Our best guess? Most modern scholars suspect Greek fire was based on either crude or refined type of petroleum – perhaps naphtha, which could easily be found in naturally occurring wells around the Black Sea. Mixed with some unknown combination of other ingredients, this would make Greek fire nothing less than a medieval equivalent of napalm.

Suggestions of what those additions to the recipe were have included resins, pine tar, animal fat, pitch, sulfur, lime, bitumen, and more. Even with today’s technology, however, we have yet to be able to replicate the characteristics of this centuries-old weapon well enough to say for certain what went into its creation.

Greek fire was a closely guarded state secret

The final thing to know about Greek fire is why, exactly, we lost that knowledge – and ironically, it’s precisely because it was so important that it was eventually lost.

So important was this weapon to the Byzantine Empire that it swiftly became a highly guarded secret: “Legend has it,” Roland explains, “that only two families knew the formula, the emperor’s family and a family named Lampros.”


But perhaps an even more intriguing possibility is that, in our drive to figure out the exact chemical composition of Greek fire, we’re concentrating on the wrong thing. 

“Greek fire was not just an incendiary,” Roland points out. “It was a weapon system, composed of dromon [ship], tube, caldron, and liquid.”

In other words, simply knowing the formula for Greek fire would not be enough to recreate its devastating effects – you’d need to know how to wield it; how to build the equipment to pump it; how to store it safely, and so much more.

And the key to the Byzantine monopoly on Greek fire? Nobody knew all of that. “To steal the secret it was necessary to steal all the components,” Roland explains. “But people with knowledge of the components were never in the same place at the same time […] the Byzantines compartmentalized knowledge of their system so that no one likely to fall into enemy hands would carry more than a fraction of the secret.”


But as crucial as this tactic was to maintaining a military advantage, it was ultimately the downfall of the Byzantine system. With knowledge of how to create Greek fire so fragmented, it was just a matter of time before the whole technology was lost.

For Greek fire to survive as a weapon, “someone had to know the whole secret,” Roland writes.

As it was, however, “the secret was comparatively safe from compromise, but simultaneously vulnerable to being lost altogether,” he explains. “Putting all the eggs in one basket makes it easy to guard the eggs, but difficult to ensure that one egg survives.”


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