At one point gas warfare was used, in the trench warfare
So, yes it was uses
World War I
The Germans used the deadly poison Mustard Gas in World War I. The British used something equivalent to this, but not exactly the same.
World War Two
No. Poison gas was first used in World War 1.
World War 1 was the first time Poison Gas was used on the battle field.
In the beginning of the war, only the Axis used poison gas (mustard gas was the first kind to be used), but by the end of the war, both sides used poison gas as a weapon.
Widely after the second world war.
Chlorine
Yes. Mustard Gas
Zyklon-B
Germany
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