Chemical weapons aren't all that new. Sparta employed a sort of napalm analog at Plataea, in 429 BC. Wood, pitch and sulfur don't sound all that dangerous - but they produce quite a lot of heat. And toxic fumes.
- "Incendiary Weapons - History"
Athens apparently didn't use the sort of (for the time) high-tech weaponry that Sparta had.
- "Obama Limits Nuclear Weapons: That's Nice"
(April 6, 2010)