Greek Fire was a very effective that kept the enemies of Constantinople and the Byzantine Emperor at bay for seven centuries.

Constantinte IV Pogantus was the Eastern Roman Emperor from 668 to 685. It was during his reign that Greek Fire was perfected. Many sources say that the inventor was Callinicus (or Kallinikus) of Heliopolis, who was a non-Muslim who escaped from Mulsim-controlled Syria and made his way to Constantinople.

To use Greek Fire as a weapon, the Byzantines threw it in pots or ejected it from tubes, held in the hand or mounted on a parapet or the prow of a ship. Once the substance had been heated and pressurized, it was ready to go. Ejecting the substance produced a loud roar and an expansive puff of smoke, resembling the breath of a dragon. The Byzantines also called it Sea Fire and Liquid Fire.

It also stuck to human flesh and wood, so it was particularly useful as an incendiary device against enemy ships or siege weapons. The Byzantines filled barrels with Greek Fire and ejected them from their own siege weapons, during land battles. They also filled jars with Greek Fire and used them in the way that soldiers today use grenades.

The only known methods of combating the superweapon were the use of salt, sand, urine, or vinegar.

Callinicus built on a substance used against Rome by the Pontus kings, during the Mithridatic Wars. The most well-known of those kings was Mithridates VI. The new formula was more refined and more deadly.

Historians differ on the set of ingredients thought to have been used to make Greek Fire. Along with the suspected main ingredient of naphtha or light petroleum, sources list any number of the following as additional ingredients:

• bitumen
• cedar resin
• lime
• petroleum
• pine resin
• pitch
• sulfur

Some historians have argued that Greek Fire must have contained gunpowder or at least some form of saltpeter, one of gunpowder's main ingredients. If that were the case, then it would be the earliest ever uses of gunpowder in the West. China is known to have invented gunpowder in the 9th Century, originally for medicinal purposes; the Chinese didn't use gunpowder as a weapon for another century or so. Byzantine armies and navies used Greek Fire for several centuries, so the addition of gunpowder as an ingredient later on is a possibility.

The first recorded use of Greek Fire by the Byzantine armies was in 673, to combat a Muslim army's siege of Constantinople. During this battle, a fleet of Greek ships flung Greek fire from prow-mounted tubes, destroying the navy on which the Muslim army depended for support. The enemies of Constantinople discovered that coming into contact with water did not extinguish Greek Fire; rather, it seemed to thrive on such contact. The invading army then broke off the siege.

Historians recorded other similar uses in 717, again to defend against an Arab army, and then in the 10th Century, against a fleet from Russia.

The precise formula used to make Greek Fire remains a mystery, having been passed only from one Byzantine emperor to the next and then lost to history. Even enemies who salvaged some of the substance were able to reverse engineer it.

As to the name, that comes from a reference made by the Crusaders, who encountered it on their many forays into the Byzantine capital. Because the word Byzantine was a modern construct and what modern historians refer to as the Byzantine Empire was, in the words of those who lived it, an extension of the Roman Empire, the substance was known to Constantinople's enemies at the time as Roman Fire.