Greek fire was an incendiary mixture utilized by the Byzantine Empire in warfare. First unleashed in the 7th century, Greek fire would go on to become a weapon that could change the tide of a battle. Ancient accounts of Greek fire tell the tale of a frightening weapon, a flammable mixture that couldn’t be extinguished with water and adhered to human flesh. Greek fire was deployed in several ways including in jars as a sort of hand grenade or to be thrown by catapult, in hand held siphons to make ancient flamethrowers, and in siphon projectors on ships. Particularly effective in naval combat, Greek fire was launched from the bows of Byzantine ships where it would ignite everything in sight – ship hulls, sails, rigging, and crew. Even if enemy ships were able to avoid a direct hit, Greek fire would stay afloat on top of the water waiting for anything to make contact with it. Making it all the more terrifying, the projectors on ships would be made to look like the heads of lions or other animals so that enemies would see creatures spitting out fire at them. Allegedly accompanied by smoke and a loud noise when projected, it is easy to see how it caused so much terror in enemy troops, some of whom would choose to drown rather than be burned alive in naval conflicts.

Greek Fire

The Effectiveness of Greek Fire

Greek fire wasn’t just terrifying though, but highly effective in combat when it was first introduced. Greek fire proved to be crucial in the defense of the Byzantine Empire, which almost certainly wouldn’t have lasted so long without it. In 678 A.D., the Byzantine capital Constantinople was facing extinction by Arab invaders. Facing a siege on land and a blockade at sea, a fleet of ships was sent out carrying Greek fire, where it would see its first combat use. Unable to extinguish the mysterious fire, the Arab fleet was decimated and the siege on Constantinople was lifted.

In 718 A.D., forty years later, Constantinople was once again under siege. And once again the Byzantine navy took to the water armed with Greek fire and crushed the Arab fleet, allowing the city to be resupplied by sea and demoralizing the enemy.

Eventually enemies would devise tactics to deal with the devastating power of Greek fire. The most obvious was to simply stay out of its somewhat limited range. Wooden structures would be covered with hides soaked in vinegar to resist catching on fire. Greek fire also had some limitations of its own. It was notoriously difficult to control and could become deadly to its own users if they didn’t exercise great caution. This meant that wind conditions and calm waters were important for Greek fire to be most effective.

What Were the Ingredients in Greek Fire?

The formula for Greek firewas a state secret kept by Byzantine elites and the exact composition has been lost. However, based on the attributes ascribed to Greek fire and materials available to the Byzantines at the time, we can speculate on the ingredients it likely contained. In descriptions, Greek fire was given several important characteristics. It was described as a liquid; it could not be extinguished with water only with vinegar, urine, and sand, and when projected from bow mounted siphons emitted smoke and a booming noise.

Throughout history many theories have been proposed about the composition of Greek fire. Most theories include some combination of naphtha, quicklime, saltpeter, sulphur, and resins. Modern consensus argues that it was probably a petroleum based concoction containing naphtha (a light crude oil) and pine resin. Resins would have helped make the liquid sticky and make it burn hotter and for a longer duration. Crude oil could have been obtained from wells around the Black Sea or in various locations around the Middle East. It is also possible that the Byzantines had different variants of Greek fire that were used in different ways. Today, our closest modern equivalent would be napalm.

How Greek Fire Remained a Mystery

At the time, incendiary weapons were not particularly new in the Mediterranean. However, no other incendiary weapons were as effective as Greek fire. In part, this was because Greek fire was not just a flammable liquid, but because the Byzantines figured out a way to project the liquid with the use of a complex weapon system. The basic mechanism is thought to have worked by heating a container filled with the mixture and pumping air into it to pressurize it. A valve would be opened to release the pressurized mixture where it would flow through a nozzle and be ignited as it exited.

Both the manufacture of Greek fire and the weapon system were highly compartmentalized. The shipwrights who built the vessels, the smiths who built the caldrons and siphons, the chemists who brewed the deadly concoction, and the operators would not all be together at the same time or even necessarily be in contact with each other. While the Byzantines were very careful not to let any fall into enemy hands, it eventually happened. However, when the Bulgars captured a stock of Greek fire complete with siphon projectors they apparently were unable to figure out how to use everything, suggesting that it took considerable technical knowledge and training to make use of it. And by 1204, the recipe for Greek fire was lost forever.