II.

Chemical Agents

Greek fire, invented in the 7th century as an incendiary mixture sprayed at the enemy, was probably the first form of chemical warfare. Gases such as tear gas, chlorine gas and phosgene (lung irritants), and mustard gas (causing burns) were first used in World War I to break the trench warfare stalemate. Flame-throwers were also tried but at first proved ineffective because of their short range. Technical improvements and the development of napalm (composed of napthenic and palmitic acids), a thickened petrol that sticks to surfaces and causes horrendous injuries, led to the widespread use of flame weapons in World War II and to its further, extensive use in the Vietnam War.

By the end of World War I, most European powers had integrated gas warfare capabilities into their armies at some level, and nerve gases such as sarin, small amounts of which cause paralysis or death, were developed in Germany between World Wars I and II. Despite the availability of gases, only Japan used them—in China—as World War II became global. After World War II, knowledge of nerve-gas manufacture became widespread.

Gases such as tear gas have been used in limited wars since World War II, such as in the Vietnam War; tear gas is also employed by civilian police forces to quell riots. The use of more deadly agents such as mustard gas and nerve gas has been generally condemned by most countries, but such weapons remain in arsenals, and there is evidence that they were used by Iraq during its war with Iran in the 1980s and that both countries continue to develop them.

Various chemical compounds, such as Agent Orange, that alter the metabolism of plants and cause defoliation, have been employed in modern jungle warfare to reduce the enemy’s cover or deprive the civilian population of necessary food crops. Such chemicals, generally sprayed from the air, also contaminate water and fish; their long-lasting effect on the entire environment and ecosystem makes them particularly devastating. Evidence exists that Agent Orange has caused cancer and birth abnormalities.