Early Thermal Weapons

Early thermal weapons were devices or substances used in warfare during the classical and medieval periods (approx 8th century BC until the mid-16th century AD) which used heat or burning action to destroy or damage enemy personnel, fortifications or territories.

Incendiary devices were frequently used as projectiles during warfare, particularly during sieges and naval battles; some substances were boiled or heated to inflict damage by scalding or burning. Other substances relied on their chemical properties to inflict burns or damage. These weapons or devices could be used by individuals, manipulated by war machines, or utilised as army strategy.

The simplest, and most common, thermal projectiles were boiling water and hot sand, which could be poured over attacking personnel. Other anti-personnel weapons included the use of hot pitch, oil, resin, animal fat and other similar compounds. Smoke was used to confuse or drive off attackers. Substances such as quicklime and sulfur could be toxic and blinding.

Fire and incendiary weapons were used against enemy structures and territory, as well as personnel, sometimes on a massive scale. Large tracts of land, towns and villages were frequently destroyed as part of a scorched earth strategy. Incendiary mixtures, such as the oil-based Greek fire, could be launched by throwing machines or administered through a siphon. Sulfur- and oil-soaked materials were sometimes ignited and thrown at the enemy, or attached to spears, arrows and bolts and fired by hand or machine. Some siege techniques—such as mining and boring—relied on combustibles and fire to complete the collapse of walls and structures.

Towards the latter part of the period, gunpowder was invented, which increased the sophistication of the weapons, and led to the eventual development of the cannon and other firearms. Development of the early weapons has continued ever since, with a number of modern war weapons, such as napalm, flame throwers, and other explosives having direct roots in the original early thermal weapons. Fire-raising and other destructive strategies can still be seen in modern strategic bombing.