Where are the gas artillery rounds?

[Marcello]

Originally Posted by Akmatov

* 1984-?? Iraq used tabun against Iran

Iraq produced a few thousands of tons of various agents, such as various types of mustard, and used a fair portion of that, mostly against iranian troops. What fun must have been manning an iranian 155mm battery in NBC gear under the local sun is probably better left to imagination...
For that matter I vaguely recall that using chemical weapons against airfields was something considered in soviet and likely still in north korean plans. Sortie rate would have taken a big hit.

Another problem with simulation of chemical or biological agents is the lack of hard evidence on the effectiveness. Lots of anecdotal stuff, but very little to no documentation as to the actual wartime use

The effects of various weapons against personnel are going to be mainly anedoctal. Testing the effects of weapons on hardware is done sparingly as it is expensive, but say sticking a few guys in a trench and experiment how many artillery rounds it actually takes to incapacitate the survivors just cannot be done. Hence you have to rely on models backed by whatever data is available.
That being said I would be extremely suprised if the various WW1 combatants did not produce substantial amounts of paperwork on their use.

I know the Taliban occasionally mortar NATO bases, but I don't know what the minimum mortar size would be for gas. You would need more than just a few rounds here and there to do any real damage, but one could sure get the infidels attention with just a few sarin induced corpses

A small number of smallish mortar/rockets rounds loaded with some home made quality agent shot at random in the direction of of your run of the mill army base aren't going to accomplish much of note. It is far more likely to get oneself killed while producing the agent and loading it in the shells.