Greek fire

Greek fire emerged because the Byzantine Empire faced existential naval threats from Arab fleets and needed a weapon so devastating that enemies would fear approaching Constantinople. A refugee from Syria—Kallinikos of Heliopolis—delivered exactly that: an incendiary compound that burned on water and could be projected from ship-mounted siphons like ancient flamethrowers.

The weapon appeared between 674 and 678 CE, during the Arab siege of Constantinople under Constantine IV. Kallinikos had fled the Arab conquest of Syria and brought knowledge of incendiary materials—possibly encountered in Persian or Middle Eastern traditions. He experimented with combinations until discovering a mixture that could be pressurized and projected from bronze tubes mounted on ship prows.

Modern scholars believe the formula centered on naphtha—light petroleum—mixed with resins, sulfur, pine or cedar pitch, and possibly quicklime. The resins thickened the mixture and intensified the flame's duration. A surviving 9th-century Latin manuscript at Wolfenbüttel identifies naphtha as the primary ingredient. The Crimean peninsula likely supplied the petroleum; Byzantine control of Black Sea trade routes gave them exclusive access to this strategic resource.

The delivery system was as revolutionary as the compound itself. Bronze siphons mounted on ships projected the flaming liquid in controlled streams—essentially flamethrowers predating modern versions by 1,200 years. Hand-held versions called cheirosiphons functioned like portable flamethrowers. Clay jars filled with the mixture could be hurled as grenades. The combination of technologies created a naval weapons system without parallel in the medieval world.

Greek fire's psychological impact matched its physical destruction. Contemporary accounts describe a roaring noise, clouds of smoke, and flames that burned especially fiercely on water—extinguishing it with seawater only spread the fire. Enemy sailors faced a weapon that negated their traditional defenses. The Byzantine fleet wrought havoc on Arab attackers in 673; Leo III used it against Arabs in 717; Romanus I destroyed a Russian fleet in the 10th century.

The Byzantines understood the weapon's strategic value and guarded its secrets with extreme care. Emperor Romanos II declared three things must never reach foreign hands: imperial regalia, royal princesses, and Greek fire. Only the third was never surrendered. Knowledge was compartmentalized—operators knew only their specific component's preparation. When Bulgarians captured 36 siphons and quantities of the compound in 814, they couldn't make the system work; they lacked the integrated knowledge of formula, pressurization, and delivery.

This secrecy ultimately doomed the technology. Unlike gunpowder, which spread across Eurasia and evolved through many hands, Greek fire's compartmentalization prevented transmission. When the Byzantine Empire fell in 1453, the complete system vanished. Modern attempts to reconstruct it have produced plausible approximations but no definitive recipe. Greek fire demonstrates how tightly-held military secrets can be lost entirely when the institution protecting them collapses.