Greek Fire

Greek fire was a fiery weapon deployed by the Byzantine Empire between the 600s and the 1300s. Its exact makeup was a fiercely guarded imperial secret that has since been lost. While historians have guessed at ingredients like saltpeter, sulfur, or quicklime, most current experts believe it was a petroleum-and-resin blend, similar to modern napalm. Byzantine crews hurled grenades packed with the substance onto enemy vessels or shot it through pipes. Because it could keep burning on water, it became a devastating naval weapon, and opposing forces tried—but failed—to replicate it.

The English name "Greek fire" became common during the Crusades. In Byzantine texts, it went by many titles: "sea fire," "Roman fire," "Median fire," "war fire," "liquid fire," "sticky fire," or "manufactured fire."

Incendiary weapons existed long before Greek fire. Ancient armies used mixtures of sulfur, petroleum, and bitumen. During the Siege of Petra (550–551), defenders threw pots of sulfur, pitch, and naphtha. The Greeks and Romans used flaming arrows, pots, and catapult-launched pouches filled with combustibles. Thucydides described a long tube on wheels that blew flames with a bellows at the Siege of Delium in 424 BC. A late 2nd- or early 3rd-century manual called the *Kestoi* recorded a recipe that ignited from heat and sunlight, meant for grenades or night attacks.

The Byzantine Emperor Anastasius I (r. 491–518) was advised by a philosopher named Proclus to use sulfur against rebel ships. The specific weapon known as Greek fire was developed around 672. The chronicler Theophanes the Confessor credited it to Kallinikos (Callinicus), a Jewish architect from Heliopolis in Syria who fled to the Romans. Theophanes wrote that Kallinikos devised a sea fire that burned Arab ships and their crews, securing a Byzantine victory. However, Theophanes also mentioned fire-carrying ships with nozzles (siphōns) a few years earlier, suggesting Kallinikos may have improved an existing weapon. Historian James Partington believed Greek fire was not a single invention but the work of chemists in Constantinople building on Alexandrian knowledge. The 11th-century chronicler George Kedrenos claimed Kallinikos came from Heliopolis in Egypt, but most scholars dismiss this. Kedrenos also told a story—considered unlikely—that Kallinikos' descendants, a family called Lampros, kept the secret into his own time.

Greek fire arrived at a critical moment. Weakened by wars with Persia, the Byzantines faced the Muslim conquests. Syria, Palestine, and Egypt had fallen, and around 672 the Arabs aimed to take Constantinople. Greek fire helped repel them during the first and second Arab sieges. It later secured victories in naval battles against the Saracens and in Byzantine civil wars, such as the revolt of the thematic fleets in 727 and Thomas the Slav's rebellion in 821–823. The central Imperial fleet used it to defeat rebel fleets. It also devastated Rus' raids on the Bosporus, especially in 941 and 1043, and was used during the Bulgarian war of 970–971, when fire-carrying ships blockaded the Danube. The weapon's importance in the struggle against the Arabs led to its discovery being credited to divine intervention.