Greek fire was an incendiary chemical weapon manufactured in and used by the Eastern Roman Empire from the seventh through the fourteenth centuries. The recipe for Greek fire was a closely-guarded state secret, but historians speculate it may have been made by combining pine resin, naphtha, quicklime, calcium phosphide, sulfur, or niter. Roman sailors would toss grenades loaded with Greek fire onto enemy ships or spray it from tubes. Its ability to burn on water made it an effective and destructive naval incendiary weapon, and rival powers tried unsuccessfully to copy the material.
Στόλος Ρωμαίων πυρπολῶν τὸν τῶν ἐναντίων στόλον, "The Roman fleet burn the opposite fleet down" – A Eastern Roman Empire / Byzantine war ship using their "secret weapon" Greek Fire against a ship belonging to the rebel Thomas the Slav, AD 821. (12th century illustration from the "Madrid Skylitzes").
Use of a cheirosiphōn ("hand-siphōn"), a portable flamethrower, used from atop a flying bridge against a castle. Illumination from the Poliorcetica of Hero of Byzantium.
Proposed reconstruction of the Greek fire mechanism by Haldon and Byrne
A catapult is a ballistic device used to launch a projectile a great distance without the aid of gunpowder or other propellants – particularly various types of ancient and medieval siege engines. A catapult uses the sudden release of stored potential energy to propel its payload. Most convert tension or torsion energy that was more slowly and manually built up within the device before release, via springs, bows, twisted rope, elastic, or any of numerous other materials and mechanisms.
Ancient mechanical artillery: Catapults (standing), the chain drive of Polybolos (bottom center), Gastraphetes (on wall)
Engraving illustrating a Roman catapult design, 1581
Roman "catapult-nest" in the Trajan's Dacian Wars
Replica of a Petraria Arcatinus