Greek Fire: The lethal ancient superweapon that changed warfare forever

The invention of Greek Fire is commonly credited to Kallinikos of Heliopolis, a Greek-speaking refugee from Syria who reportedly arrived in Constantinople around 668 AD.

The city at the time faced repeated attacks from the Umayyad Caliphate, and the Byzantines needed new weapons to maintain their naval superiority.

Kallinikos, who may have worked as an alchemist or military engineer, offered a chemical formula unlike anything the empire had seen before.

Some later sources suggest that Greek Fire may have existed in cruder forms prior to his arrival, and that Kallinikos refined an earlier fire-making substance into a more effective and ready to use weapon.

However, some modern scholars question the historical accuracy of Kallinikos's role, as contemporary evidence remains scarce. 

Regardless, during the reign of Emperor Constantine IV, the empire’s leadership quickly recognised the opportunity to reverse the naval disadvantage.

Kallinikos reportedly worked with a small team of Byzantine technicians to create a forced liquid fire-making that could be launched from siphons mounted on warships.

The resulting device projected fire in a controlled stream, setting fire to sails, wooden hulls, and the men aboard enemy vessels. 

In surviving Byzantine records, Greek Fire appears in accounts of the Arab attacks of Constantinople, though the exact dating and details vary.

Some sources, such as those later attributed to Theophanes the Confessor, mention the weapon in relation to the events of the 670s, but modern historians debate whether it was actually used at that time or developed closer to the early 8th century.

The weapon turned the tide of war. Imperial authorities restricted access to the formula, reserving it for trusted military leaders or members of the emperor’s inner circle.

Some accounts suggest that those who possessed knowledge of its composition were forbidden to record it in writing or share it outside imperial circles.

Each ruler treated the knowledge as a tool of imperial preservation. Although execution for revealing the formula is often claimed in later sources, no direct historical records confirm such punishments. 

As dynasties changed and the empire weakened, the secrecy surrounding the formula became a liability.

Without written records or widespread technical understanding, the weapon eventually disappeared along with the men who knew how to produce it. 

The formula for Greek Fire has never been confirmed. Although historians and chemists have speculated for centuries, no original record survived.

Likely ingredients include petroleum, sulphur, quicklime, pine resin, and perhaps metal powders.

These substances created a sticky, flammable mix when they were combined correctly, and it may have set on fire upon exposure to air or in reaction with water.

In specialised military workshops, teams probably prepared the mixture under strict conditions.

Open flames, accidental spills, or improper ratios could result in sudden combustion, so any mistakes often had fatal consequences. 

Alongside the chemical mixture, the Byzantines devised careful methods to deliver it.

Siphons made of bronze, which were mounted on ships or city walls, projected Greek Fire in arcs of flaming liquid.

These devices were operated by pumps or bellows and sent the fire directly into enemy ships or siege engines.

For close-quarters combat, the Byzantines developed alternative methods. Some sources mention clay pots that held fire-making substances.

They exploded on impact and set fire to wood, cloth and other flammable materials.

While these weapons may have included similar mixes, it is uncertain whether they used true Greek Fire.

Other handheld devices may have resembled tubes or small flamethrowers used during city defence or surprise attacks.

These portable versions, sometimes called cheirosiphłnes, allowed soldiers to carry and discharge fire directly at advancing enemies, a rare innovation in ancient warfare. 

Under certain conditions, engineers may have also experimented with timed ignition.

Some devices might have included materials that delayed combustion until the weapon reached its target.

This would explain reports of delayed bursts of flame or fire that erupted on contact with water. 

Greek Fire reached its full effectiveness in naval engagements. Mounted at the prow of Byzantine dromons, the siphons allowed crews to spray fire at enemy ships before they reached boarding range.

These fast, easy to handle warships combined speed with deadly firepower, often turning the tide before a battle could begin.

Flames erupted from the nozzles in a forced stream, striking enemy decks and spreading rapidly.

The fire clung to wood, cloth, and skin, overwhelming most attempts to extinguish it. 

As a result, enemy fleets often broke formation and retreated in panic. Sailors who had never seen such fire leapt overboard in fear, only to discover that the substance floated and burned on water.

The weapon’s mental effect outweighed even its physical damage, as no one could predict where or when it would strike, and no one knew how to stop it once it spread. 

On land, the Byzantines used Greek Fire to defend their cities and repel attacks.

From the walls of Constantinople, soldiers launched fire from siphons or threw fire-making pots at siege towers and scaling ladders.

Flames consumed wooden equipment before it reached the walls. Attackers scattered in confusion as defenders rained fire down upon them. 

In fortified encounters, defenders may have employed traps using Greek Fire.

Ditches filled with the substance could be set on fire when attackers advanced, creating walls of flame that halted enemy movement.

These tactics allowed small defending forces to repel larger armies using fear and environmental control.

Outside the empire, no one mastered the formula. Observers from Western Europe and the Islamic world described the weapon with awe but offered mixed details.

Writers such as Anna Komnene and Leo the Deacon included descriptions in their histories, while Islamic scholars like al-Mas'udi marvelled at its effects.

Crusaders who passed through Byzantine territory never gained access to it, and no equivalent appeared in their arsenals.

Later attempts to replicate it, such as the "wildfire" used during the Siege of Acre, failed to match its power. 

During the Arab siege of Constantinople from 674 to 678 AD, some sources suggest that Greek Fire was used to repel Umayyad fleets, though the exact timing of its first deployment remains uncertain.

Byzantine warships may have been equipped with siphons that set enemy ships ablaze.

Entire squadrons disappeared beneath burning waves, and the siege collapsed after repeated naval defeats. 

In 717–718 AD, another massive Arab force arrived to surround the city. Emperor Leo III prepared his defences carefully.

As Arab ships entered the Sea of Marmara, Byzantine vessels attacked using Greek Fire.

The weapon burned ships to the waterline and helped break the naval block. The land army, left unsupported, withdrew. 

Centuries later, in 941 AD, the Rus’ launched an attack from ships on the Bosporus.

Their longships, fast but open to attack, became easy targets for the Byzantine fleet.

Siphon fire engulfed the invaders’ vessels, and survivors described rivers of flame that spread across the sea. 

Reports occasionally mention limited Byzantine use of incendiaries during the First Crusade, but firm evidence of Greek Fire's deployment is lacking.

By that time, the formula had likely declined in quality or quantity. Earlier battles, such as those fought under Romanos I Lekapenos, had demonstrated more effective deployment and control. 

Each recorded battle reveals the same pattern: Greek Fire shifted the balance.

Where it appeared, it destroyed fleets, ended attacks, and maintained Byzantine control over strategic waters. 

Since the nineteenth century, historians and chemists have attempted to reconstruct Greek Fire.

Relying on written accounts, many experiments used combinations of petroleum, sulphur, resin, and quicklime.

These mixtures produced fire that could burn on water or stick to surfaces, but no version achieved the full range of effects described in medieval sources. 

In controlled environments, some tests created a burning liquid that resisted water and that spread when the mixture was doused.

The fire travelled several metres and set on fire on impact when it was launched from forced tubes.

Despite this success, the flames lacked the cling and intensity described in primary accounts. 

Part of the mystery lies in the delivery system. Byzantine siphons operated under force, and their construction remains unclear.

Without the right working parts, even the correct chemical mixture would fall short of full power.

Engineers today have attempted to reconstruct such devices using descriptions of bellows, valves, and bronze nozzles, though none match the historical accounts completely. 

As mentioned earlier, following the fall of Constantinople in 1453, knowledge of the formula disappeared.

Earlier invasions, political chaos, and assassinations may have removed the few individuals who still held the secret.

Without written records or trained successors, the chain of knowledge ended.