Early thermal weapons, which used heat or burning action to destroy or damage enemy personnel, fortifications or territories, were employed in warfare during the ancient and post-classical periods (approximately the 8th century BC until the mid-16th century AD).
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, thrown by siege engines, or utilised as army strategy. Incendiary mixtures, such as the petroleum-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.