>>12065691I don't have a link available. The Great War youtube channel has great detail on the whole war.
Almost half of the deaths caused by gas on the Western Front (which were thousands, not tens of thousands), were caused on the first day chlorine gas was used, with almost 900 killed. That same day German artillery claimed 1,800 lives.
The point to gas isn't to kill but to suppress. Georg Bruchmuller (the artillery genius) would drop gas on artillery to prevent counter-battery fire, and John Monash used it in conjunction with smoke to blind the enemy while he attacked with tanks. In both cases the gas was used:
1. In conjunction with other types of shells.
2. In conjunction with other forms of attack.
The exception was Mustard gas which is persistent and heavier than air, so it would settle into trenches and shell craters preventing them from being used for a while. But that still doesn't get you safely across no-mans-land.