History of Europe

Why was poison not an effective weapon during world war 1?

Poison gas was widely and effectively used by both sides during World War I. During the first gas attack, at the Second Battle of Ypres, the Germans released 150 tons of chlorine gas from 5,730 cylinders that were opened simultaneously causing great casualties among the French and Algerian soldiers. It is estimated that 10,000 gas cylinders were used during World War I. Poison gas would have been used more extensively if not for retaliatory measures and technological improvements.