But why put pesticide in a shell ?
Because it was believed for years to be an effective weapon against conventional forces..
That is, until conventional forces began equipping their troops with countermeasures..
The Germans used Mustard Gas and Lewisite and Chlorine gas against Allied forces in WW1.
They found it to be effective if "conditions were favorable"..
If conditions were "not favorable", it could backfire on the user.. (double edged sword)
Still, it was a risk vs. reward sort of thing, and war is a gamble anyway..
That's why my grandfather suffered from exposure to mustard gas until the day he died, one lung completely gone, and the remaining one so damaged he spent every winter in a vet's hospital huddled in an oxygen tent to stay alive..
He "lived" like that for some 35 years before finally passing away..
I still remember the scars on his arms, neck, back, legs, waist.. everywhere..
He and his fellows didn't have "gas masks".. there wasn't any such items issued back then..