What was Greek Fire?

Greek fire was apparently introduced about 672 AD in the reign of Emperor Constantine Pogonatus, the inventor being an architect called Callinicus of Heliopolis. It was used in the great Siege of Constantinople and became a most important weapon to the Byzantines. Greek fire was used with success in their campaigns up to the 13th century.

Its exact composition is still a mystery. Naptha or petroleum is thought to have been the principal ingredient, probably with sulphur or pitch and other materials added. It is not clear, however, how it was ignited, but quicklime was probably used, mixed with the main ingredients at the last moment. Once lit, the substance was very difficult to extinguish needing sand or vinegar to do so. The mixture was packed into siphons which were mounted in the bows of galleys.