History of chemical warfare
Chemical weapons have been a part of warfare in most societies for centuries. However, their usage has been extremely controversial since the 20th century. Ancient and medieval times Ancient Greek myths about Heracles poisoning his arrows with the venom of the Hydra monster are the earliest references to toxic weapons in western literature. Homer's epics, the Iliad and the Odyssey, allude to poisoned arrows used by both sides in the legendary Trojan War (Bronze Age Greece). Some of the earliest surviving references to toxic warfare appear in the Indian epics Ramayana and Mahabharata. The "Laws of Manu," a Hindu treatise on statecraft (c. 400 BC) forbids the use of poison and fire arrows, but advises poisoning food and water. Kautilya's "Arthashastra", a statecraft manual of the same era, contains hundreds of recipes for creating poison weapons, toxic smokes, and other chemical weapons. Ancient Greek historians recount that Alexander the Great encountered poison arrows and fire incendiaries in India at the Indus basin in the 4th century BC. Arsenical smokes were known to the Chinese as far back as BC and Sun Tzu's "Art of War" (c. 200 BC) advises the use of fire weapons. In the second century BC, writings